Patent Grant
8835111
The invention relates to methods and products, in particular microarrays, for in vitro genotyping of multiple sclerosis (MS) associated genetic variations and to methods for assessment of MS disease severity.
Multiple Sclerosis is an autoimmune chronic inflammatory disease, characterized by a progressive demyelination of the central nervous system. While its origin still remains unknown, its multifactorial etiology is well known, consisting of a clear genetic component regulated by several environmental factors.
Clinical evolution of MS is very heterogeneous, and there are different phenotypes present. These range from a very severe form where patients worsen rapidly (known as primary progressive MS), to a more benign form, where the patient practically recovers completely after each disease relapse (known as relapsing remitting MS). Nowadays, disease diagnostics is clinically based, relying on three main points: clinical history, neurologic exploration and use of several techniques (Magnetic Resonance Imaging, analysis of cerebrospinal fluid and evoked potentials).
Currently there is no treatment that will cure MS. MS therapies aim at controlling symptoms and maintaining patient's quality of life. With such treatments, the number of relapses is controlled to a certain level, allowing partial prevention of consequences that may cause such relapses. The primary aims of therapy are returning function after an attack, preventing new attacks, and preventing disability. As with any medical treatment, medications used in the management of MS have several adverse effects. Disease-modifying treatments reduce the progression rate of the disease, but do not stop it. As multiple sclerosis progresses, the symptomatology tends to increase. The disease is associated with a variety of symptoms and functional deficits that result in a range of progressive impairments and disability.
Management of these deficits is therefore very important. Both drug therapy and neurorehabilitation have shown to ease the burden of some symptoms, though neither influences disease progression. As for any patient with neurologic deficits, a multidisciplinary approach is key to limiting and overcoming disability; however, there are particular difficulties in specifying a ‘core team’ because people with MS may need help from almost any health profession or service at some point. Similarly, for each symptom there are different treatment options. Treatments should therefore be individualized depending both on the patient and the physician.
Aspects of the invention relate to methods of analyzing a patient's genotype, for example through analysis of SNPs, optionally combined with clinical-environmental data, for prognosis and treatment management of MS patients, leading to personalized medicine. Accordingly, in a first aspect the present invention provides a method of assessing a MS disease severity phenotype in a human subject having or suspected of having MS, the method comprising determining the genotype of the subject at one or more positions of single nucleotide polymorphism (SNP) selected from those listed in Table 10 and/or a SNP in linkage disequilibrium with any one of said SNPs. The SNPs may be as disclosed in the NCBI dbSNP build 131, Homo sapiens genome build 37.1 and/or NCBI dbSNP build 129, Homo sapiens build 36.3. The presence of one or more “risk alleles” as identified in Table 10 at one or more of the SNPs indicates that the subject has a higher probability of having a greater severity of MS. In some cases, the method of this and other aspects of the invention comprises determining that the subject does have at least one risk allele at at least one of said SNPs. In other cases, the subject may be determined to be free from said risk alleles at at least one of said SNPs. In some cases, the method of this and other aspects of the invention, the presence of:
In some cases, a more severe multiple sclerosis disease phenotype may be a phenotype selected from: a multiple sclerosis severity score (MSSS) of 2.5 or greater; an increase in size and/or distribution of T2 brain lesions; an increased number of focal lesions in the spinal cord; an increased T2 lesion load in the brain; and the presence of diffuse abnormalities in the spinal cord. Optionally, the method of this and other aspects of the invention may comprise determining the genotype of the subject at 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 35, 40, 45, 50, 55 or more of said SNPs. Optionally, the method of the invention further comprises the measurement of at least one clinical variable, such as a clinical variable is selected from: age of the subject at onset of multiple sclerosis, gender of the subject and type of multiple sclerosis at onset of multiple sclerosis. The method of the invention may, in some cases, comprise determining the genotype of the subject at a specific combination or sub-set of SNPs selected from those listed in Table 10, such as the first 2, first 3, first 4, first 5 or first 6. Accordingly, in some cases, the method of the invention comprises determining the genotype of the subject at: at least rs2107538, rs1137933 and rs1318; at least rs2107538, rs1137933, rs1318, rs2069763, rs423904 and rs876493. In some cases, the method of the invention comprises determining the genotype of the subject at substantially all of the SNPs listed in Table 10. In some cases, the method of the invention comprises determining the genotype of the subject at only the SNPs listed in Table 10 and/or only SNPs in linkage disequilibrium with one or more of the SNPs listed in Table 10.
In certain cases, the method of the invention comprises determining the genotype of the subject at a sub-set of SNPs of those listed in Table 10, which sub-set is indicative of a particular MS disease severity phenotype. Methods for assessing particular MS disease severity phenotypes, such as a multiple sclerosis severity score (MSSS) of 2.5 or greater; an increase in size and/or distribution of T2 brain lesions; an increased number of focal lesions in the spinal cord; an increased T2 lesion load in the brain; and the presence of diffuse abnormalities in the spinal cord, may be combined to yield assessment of multiple specific MS disease severity phenotypes or performed independently.
In particular, the method of the invention may be for assessing multiple sclerosis severity score (MSSS), such as whether or not the subject has an MSSS score of 2.5 or greater, wherein the method comprises determining the genotype of the subject at at least 2 of the following positions of SNP: rs423904, rs876493, rs1137933, rs1318, rs2069763, rs2107538, rs3756450, rs12047808, rs10259085, rs1042173, rs6077690, rs1611115, rs4473631, rs2032893, rs2066713, rs260461, rs3787283, rs6917747, rs2049306, rs12861247, rs4404254, rs4680534, rs17641078, rs2187668, rs7528684, rs7577925, rs1805009, rs3741981, rs12202350, rs28386840, rs2028455, rs10492503, rs8049651, rs13353224, rs1555322, rs10243024 and rs6570426, wherein the presence of one or more of the risk alleles shown in Table 10 at one or more of said SNPs is indicative of having an MSSS score of 2.5 or greater. For example, the method may comprise determining the genotype of the subject at at least the following positions of SNP: rs2107538, rs1137933, rs1318, rs2069763, rs423904 and rs876493. Methods for assessing multiple sclerosis severity score (MSSS) of a subject may advantageously combine genotyping SNPs as specified above with determining at least 1, 2 or 3 clinical variables selected from: age of the subject at onset of multiple sclerosis, gender of the subject and type of multiple sclerosis at onset of multiple sclerosis. Thus, the method of the invention may comprise assessment of MSSS score utilising a model which combines the SNPs and clinical variables shown in Table 3, Table 3B and/or Table 3C, optionally employing the respective coefficient for each SNP and/or clinical variable shown in column “B” of said table or tables
In certain cases, the method of this and other aspects of the invention may be for assessing the probability of increased size and/or distribution of T2 brain lesions in the subject, wherein the method comprises determining the genotype of the subject at at least 2, 3 or 4 of the following positions of SNP: rs2213584, rs2227139, rs2076530 rs876493, rs9808753, rs2074897, rs762550, rs2234978, rs3781202.
In certain cases, the method of this and other aspects of the invention may be for assessing the probability of increased T2 lesion load in the brain, wherein the method comprises determining the genotype of the subject at at least 1, 2, 3 or 4 of the following positions of SNP: rs2107538, rs12861247, rs2074897 and rs7995215, such as determining the genotype of the subject at: rs12861247, rs2074897 and rs7995215.
In certain cases, the method of this and other aspects of the invention may be for assessing an increased number of focal lesions in the spinal cord, wherein the method comprises determining the genotype of the subject at at least 1, 2, 3 or 4 of the following positions of SNP: rs3135388, rs2395182, rs2239802, rs2227139, rs2213584, rs3087456, rs10492972, rs12202350, rs8049651, rs8702 and rs987107, such as determining the genotype of the subject at: rs3135388, rs3087456 and rs2227139.
In certain cases, the method of this and other aspects of the invention may be for assessing the presence of diffuse abnormalities in the spinal cord, wherein the method comprises determining the genotype of the subject at at least 1, 2, 3 or 4 of the following positions of SNP: rs1350666, rs3808585, rs4128767, rs6457594, rs7208257 and rs7956189.
The method in accordance with this and other aspects of the invention may, in some cases, be carried out in vitro using a nucleic acid-containing sample that has been obtained from the subject. In some cases the genotype of the subject at said one or more positions of SNP may be determined indirectly by determining the genotype of the subject at a position of SNP that is in linkage disequilibrium with said one or more positions of SNP, while in some cases the genotype of the subject at said one or more positions of SNP may be determined directly by identifying one or both alleles at said one or more positions of SNP.
In accordance with the method of this and other aspects of the invention, determining the genotype of the subject at said one or more positions of SNP may comprise:
In accordance with the method of this and other aspects of the invention the method may comprise amplifying DNA from a sample that has been obtained from the subject, wherein said amplifying comprises contacting the DNA with at least one forward primer as listed in Table 8 and at least one reverse primer as listed in Table 9.
In a further aspect, the present invention provides an array of probes for use in a method according to the invention, wherein the array comprises:
In a further aspect, the present invention provides methods of evaluating disease severity in a patient having multiple sclerosis, including obtaining a DNA sample from the patient, and determining the presence or absence of two or more single nucleotide polymorphisms (SNPs) associated with severity of the disease, wherein the presence of two or more SNPs associated with severity of the disease indicates a likelihood of increased disease severity. In some embodiments the two or more SNPs associated with the disease comprise SNPs in PNMT, IL1R, CCL5, IL2, PITPNC1 or NOS2A. In certain embodiments the two or more SNPs are selected from those listed in Table 10. In certain embodiments, the two or more SNPs associated with the disease are selected from the group consisting of 2073 Intron2 C/T (rs423904), rs876493, rs1137933, rs1318, rs2069763 and rs2107538. In certain embodiments the two or more SNPs associated with the disease are selected from the group consisting of rs3135388, rs2395182, rs2239802, rs2227139, rs2213584, rs3087456 and rs2107538.
The presence or absence of two or more SNPs associated with severity of the disease can be determined by any method known in the art such as a gene chip, bead array, RFLP analysis, and/or sequencing. In some embodiments the two or more SNPs associated with the disease comprise SNPs in PNMT, IL1R, CCL5, IL2, PITPNC1 or NOS2A. In certain embodiments the two or more SNPs associated with the disease are selected from the group consisting of, rs876493, rs1137933, rs1318, rs2069763 and rs2107538. In certain embodiments the two or more SNPs associated with the disease are selected from the group consisting of rs1137933, rs1318, rs2069764 and rs2107538.
Aspects of the invention relate to SNPs associated with increased T2 lesion load in the brain. In some embodiments the SNP is associated with an increased number of focal spinal cord abnormalities. In some embodiments the two or more SNPs are in linkage disequilibrium. In certain embodiments the two or more SNPs are in linkage disequilibrium with SNPs selected from the group consisting of rs2239802, rs2213584, rs3135388, 2213584 rs2227139, rs1137933, rs1318, rs2069764 and rs2107538.
In some embodiments methods described herein further include the measurement of one or more clinical variables such as age of onset, gender, and/or type of onset of disease. In some embodiments disease severity is based on an MS severity scale such as the Multiple Sclerosis Severity Score (MSSS) test, the Kurtzke Expanded Disability Status Scale (EDSS), or the Multiple Sclerosis Functional Composite (MSFC) measure.
In some embodiments the presence or absence of at least 6 SNPs is determined. In certain embodiments the two or more SNPs are selected from the group consisting of 2073 Intron2 C/T (rs423904), rs876493, rs1137933, rs1318, rs2069763, rs2107538, rs3135388, rs2395182, rs2239802, rs2227139, rs2213584 and rs3087456. In certain embodiments at least one of the SNPs is in linkage disequilibrium with a SNP selected from the group consisting of 2073 Intron2 C/T (rs423904), rs876493, rs1137933, rs1318, rs2069763, rs2107538, rs3135388, rs2395182, rs2239802, rs2227139, rs2213584 and rs3087456. In some embodiments methods described herein include use of one or more probe sets listed in Table 7. In some embodiments methods described herein include at least one forward primer from Table 8 and one reverse primer from Table 9.
Aspects of the invention relate to methods of designing a treatment regimen for a patient having multiple sclerosis, including obtaining a DNA sample from the patient, determining the presence or absence of two or more single nucleotide polymorphisms (SNPs) associated with severity of the disease, wherein the presence of two or more SNPs associated with severity of the disease indicates a likelihood of increased disease severity, and designing the treatment regimen based on the presence or absence of the SNPs associated with the disease. In some embodiments the treatment regimen comprises early or elevated doses of glatiramer acetate, vitamin D, interferon beta-1a or -1b, natalizumab, mitoxantrone, and/or corticosteroids.
Aspects of the invention relate to methods of treating a patient having a prognosis of increased disease severity, comprising early or elevated doses of glatiramer acetate, vitamin D, interferon beta-1 a or -1 b, natalizumab, mitoxantrone, and/or corticosteroids.
Aspects of the invention relate to methods of identifying SNPs associated with severity of symptoms in multiple sclerosis, including obtaining a DNA sample from a patient having multiple sclerosis, identifying SNPs in the DNA, wherein the SNPs comprise two or more of the SNPs listed in Table 1, performing an MRI on the patient to determine spatial distribution of T2 brain lesions, T2 lesion load, presence of diffuse abnormalities and/or number of spinal cord lesions, comparing identified SNPs with the spatial distribution of T2 brain lesions, T2 lesion load, presence of diffuse abnormalities and/or number of spinal cord lesions, and identifying the SNPs that correlate with spatial distribution of T2 brain lesion, T2 lesion load, presence of diffuse abnormalities and/or number of spinal cord lesions, wherein the SNPs that correlate with spatial distribution of T2 brain lesions, T2 lesion load, presence of diffuse abnormalities and/or number of spinal cord lesions, are SNPs associated with severity of symptoms in multiple sclerosis. In some embodiments at least one of the SNPs is in linkage disequilibrium with a SNP listed in Table 1. In some embodiments identifying SNPs associated with severity of symptoms in multiple sclerosis further comprises consideration of clinical data.
Aspects of the invention relate to methods of evaluating disease severity, as measured using the Multiple Sclerosis Severity Score (MSSS) test, the Kurtzke Expanded Disability Status Scale (EDSS), and/or the Multiple Sclerosis Functional Composite measure (MSFC), in a patient having multiple sclerosis, the method including obtaining a DNA sample from the patient, and determining the presence or absence of two or more single nucleotide polymorphisms (SNPs), wherein said SNPs comprise two or more of the SNPs listed in Table 1, and wherein the presence of said two or more SNPs indicates a likelihood of increased disease severity. In some embodiments evaluating disease severity further comprises consideration of clinical data. In some embodiments at least one of the SNPs is in linkage disequilibrium with a SNP listed in Table 1.
Aspects of the invention relate to methods of evaluating the severity of spinal cord lesions in a patient having multiple sclerosis, the method including obtaining a DNA sample from the patient, and determining the presence or absence of two or more single nucleotide polymorphisms (SNPs) associated with spinal cord lesions, wherein the presence of two or more SNPs associated with spinal cord lesions indicates a likelihood of increased disease severity. In some embodiments the two or more SNPs are selected from the group consisting of rs3135388, rs2395182, rs2239802, rs2227139, rs2213584 and rs3087456. In certain embodiments one of the SNPs is rs3135388. In some embodiments the two or more SNPs are selected from the group consisting of 2073 Intron2 C/T (rs423904), rs876493, rs1137933, rs1318, rs2069763, rs2107538, rs3135388, rs2395182, rs2239802, rs2227139, rs2213584 and rs3087456. In certain embodiments at least one of the SNPs is in linkage disequilibrium with a SNP selected from the group consisting of 2073 Intron2 C/T (rs423904), rs876493, rs1137933, rs1318, rs2069763, rs2107538, rs3135388, rs2395182, rs2239802, rs2227139, rs2213584 and rs3087456.
Aspects of the invention relate to method of prognosing the likelihood of T2 lesions and/or T2 lesion load in a patient having multiple sclerosis, the method including obtaining a DNA sample from the patient, and determining the presence or absence of SNP rs2107538, wherein the presence of SNP rs2107538 indicates a likelihood of T2 lesions and/or T2 lesion load in the patient.
Aspects of the invention relate to methods where determining the presence or absence of SNPs includes (a) providing, for each genetic variation to be genotyped, at least 2 oligonucleotide probe pairs, wherein: (i) one pair consists of probes 1 and 2, and the other pair consists of probes 3 and 4; (ii) one probe in each pair is capable of hybridising to genetic variation A and the other probe in each pair is capable of hybridising to genetic variation B; (iii) each probe is provided in replicates; and (iv) the probe replicates are each coupled to a solid support; (c) amplifying and detectably labelling the target DNA; (d) contacting the target DNA with the probes under conditions which allow hybridisation to occur, thereby forming detectably labeled nucleic acid-probe hybridisation complexes, (e) determining the intensity of detectable label at each probe replica position, thereby obtaining a raw intensity value; (f) optionally amending the raw intensity value to take account of background noise, thereby obtaining a clean intensity value for each replica; and (g) applying a suitable algorithm to the intensity data from (e) or (f), thereby determining the genotype with respect to each genetic variation, wherein application of the algorithm comprises calculating an average intensity value from the intensity values for each of the replicas of each probe and wherein the algorithm uses three Fisher linear functions that characterize each of the three possible genotypes AA, AB or BB for the genetic variation.
Aspects of the invention relate to kits for evaluating severity of disease in a subject having multiple sclerosis, the kit including: (i) at least one set of probes listed in table 7; optionally (ii) instruction for genotyping analysis as described in claim H1; and optionally (iii) instructions for determining the severity MS phenotype from the outcomes. Aspects of the invention relate to PCR amplification kits comprising at least one pair of PCR primers from tables 8 and 9, a thermostable polymerase, dNTPs, a suitable buffer, and optionally instructions for use.
Further aspects of the invention relate to a computational method of deriving a probability function for use in determining an MS severity phenotype in a subject, including applying a probability function such as stepwise multiple logistic regression analysis to outcome data and phenotype data obtained from a suitable study population of individuals, wherein each individual is of known clinically determined phenotype with respect to the Multiple Sclerosis severity phenotype, thereby deriving a probability function which produces a statistically significant separation between individuals of different phenotype in the population; wherein: (i) the phenotype data comprises the known clinically determined phenotype of each individual; (ii) the outcomes data for each individual comprises the genotype of the individual at each SNP in a set of SNPs; and wherein: (a) the probability function is for distinguishing or differentially diagnosing MS severity phenotype, and the set of SNPs is selected from the set of MS severity phenotype discriminating SNPs in Table 3; (b) the probability function is for prognosing MS disease severity phenotype and the set of SNPs is selected from the set of MS disease severity discriminating SNPs in Table 3; and/or (c) the probability function is for prognosing MS disease severity phenotype and the set of SNPs is selected from the set of MS disease severity discriminating SNPs in Table 10.
The present invention includes the combination of the aspects and preferred features described except where such a combination is clearly impermissible or is stated to be expressly avoided. These and further aspects and embodiments of the invention are described in further detail below and with reference to the accompanying examples and figures.
The Sequence Listing is submitted as an ASCII text file in the form of the file named Sequence_Listing.txt, which was created on Sep. 9, 2011, and is 173,767 bytes, which is incorporated by reference herein.
Multiple Sclerosis (MS) is a multifocal inflammatory demyelinating disease of the central nervous system (CNS), characterized by inflammation, demyelination and axonal loss resulting in a highly variable clinical presentation. Most patients suffer from relapsing-remitting (RR) MS, experiencing waves of inflammation leading to alternating periods of disability (relapses) and stable disease (remissions). The RRMS phase usually leads to progressive and irreversible disability (the secondary progressive [SP] phase). For a subset of patients, the disease is progressive from onset (primary progressive [PP] MS). Treatment decisions are based on the occurrence of relapses, and the development of white matter lesions visible on MRI. Brain lesion volume and distribution however are highly variable among MS patients, and correlate only moderately with disability. As treatment guidelines would strongly benefit from a better understanding of this variability, the present invention is drawn to methods of genetic screening and predicting severity of disease using genetic information that correlates with increased numbers of lesions in the brain, optic nerve, or spinal cord.
Aspects of the invention relate at least in part to the surprising discovery that MS severity can be associated (e.g., statistically) with one or more genetic markers. As used herein, a genetic marker refers to a DNA sequence that has a known location on a chromosome. Several non-limiting examples of classes of genetic markers include RFLP (restriction fragment length polymorphism), AFLP (amplified fragment length polymorphism), RAPD (random amplification of polymorphic DNA), VNTR (variable number tandem repeat), microsatellite polymorphism, SNP (single nucleotide polymorphism), STR (short tandem repeat), and SFP (single feature polymorphism).
In some embodiments, genetic markers associated with the invention are SNPs. As used herein a SNP or “single nucleotide polymorphism” refers to a specific site in the genome where there is a difference in DNA base between individuals. In some embodiments the SNP is located in a coding region of a gene. In other embodiments the SNP is located in a noncoding region of a gene. In still other embodiments the SNP is located in an intergenic region. It should be appreciated that SNPs exhibit variability in different populations. In some embodiments, a SNP associated with the invention may occur at higher frequencies in some ethnic populations than in others. In some embodiments, SNPs associated with the invention are SNPs that are linked to MS. In certain embodiments a SNP associated with the invention is a SNP associated with a gene that is linked to MS. A SNP that is linked to MS may be identified experimentally. In other embodiments a SNP that is linked to MS may be identified through accessing a database containing information regarding SNPs. Several non-limiting examples of databases from which information on SNPs or genes that are associated with human disease can be retrieved include: NCBI resources, The SNP Consortium LTD, NCBI dbSNP database, International HapMap Project, 1000 Genomes Project, Glovar Variation Browser, SNPStats, PharmGKB, GEN-SniP, and SNPedia. In some embodiments, SNPs associated with the invention comprise two or more of the SNPs listed in Table 1 and/or Table 10. In some embodiments 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30 or more than 30 SNPs are evaluated in a patient sample. In some embodiments, multiple SNPs are evaluated simultaneously while in other embodiments SNPS are evaluated separately.
SNPs are identified herein using the rs identifier numbers in accordance with the NCBI dbSNP database, which is publically available at: http://www.ncbi.nlm.nih.gov/projects/SNP/. As used herein, rs numbers refer to the dbSNP build 129, Homo sapiens build 36.3 available from 14 Apr. 2008 and/or dbSNP build 131, Homo sapiens build 37.1 available from 2 Feb. 2010. Except where indicated otherwise, the rs identifiers are identical for dbSNP build 129, Homo sapiens build 36.3 and dbSNP build 131, Homo sapiens build 37.1.
In some embodiments, SNPs in linkage disequilibrium with the SNPs associated with the invention are useful for obtaining similar results. As used herein, linkage disequilibrium refers to the non-random association of SNPs at two or more loci. Techniques for the measurement of linkage disequilibrium are known in the art. As two SNPs are in linkage disequilibrium if they are inherited together, the information they provide is correlated to a certain extent. SNPs in linkage disequilibrium with the SNPs included in the models can be obtained from databases such as HapMap or other related databases, from experimental setups run in laboratories or from computer-aided in-silico experiments. Determining the genotype of a subject at a position of SNP as specified herein, e.g. as specified by NCBI dbSNP rs identifier, may comprise directly genotyping, e.g. by determining the identity of the nucleotide of each allele at the locus of SNP, and/or indirectly genotyping, e.g. by determining the identity of each allele at one or more loci that are in linkage disequilibrium with the SNP in question and which allow one to infer the identity of each allele at the locus of SNP in question with a substantial degree of confidence. In some cases, indirect genotyping may comprise determining the identity of each allele at one or more loci that are in sufficiently high linkage disequilibrium with the SNP in question so as to allow one to infer the identity of each allele at the locus of SNP in question with a probability of at least 90%, at least 95% or at least 99% certainty.
As used herein MS or multiple sclerosis refers to a progressive neurodegenerative disease involving demyelination of nerve cells. Several non-limiting classifications of MS include: relapsing-remitting (RRMS) (typically characterized by partial or total recovery after attacks (also called exacerbations, relapses, or flares)), secondary progressive MS (SPMS) (generally characterized by fewer relapses, with an increase in disability and symptoms), and primary progressive MS (PPMS) (generally characterized by progression of symptoms and disability without remission).
Some non-limiting examples of symptoms of MS include: fatigue (also referred to as MS lassitude), muscle fatigue, paresthesias, difficulty in walking and/or balance problems, abnormal sensations such as numbness, prickling, or “pins and needles”, pain, bladder dysfunction, bowel dysfunction, changes in cognitive function (including problems with memory, attention, concentration, judgment, and problem-solving), dizziness and vertigo, emotional problems (e.g., depression), sexual dysfunction, and vision problems. In some embodiments, symptoms of MS can include partial or complete paralysis (such as blurred or double vision, red-green color distortion, or blindness in one eye), headache, hearing loss, itching, seizures, spasticity, speech and swallowing disorders, and tremors. In some embodiments, clinical symptoms of MS can include increased CD4:CD8 cell ratio compared to normal, decreased number of CD14+ cells compared to normal, increased expression of HLA-DR on CD14+ cells compared to normal CD14+ cells, increased levels of activated monocytes or macrophages compared to normal, the presence of proliferating macrophages, and decreased serum IgG and/or IgM compared to normal, where “normal” as used in this context refers to a subject who does not have MS.
Previous studies have explored patterns of spatial lesion distribution in MS patients. Without wishing to be bound by any theory, one potential factor underlying differences in lesion burden and spatial lesion distribution among MS patients may be found in pathological and immunological heterogeneity: studies on spatial lesion distribution throughout the brain demonstrated differences in lesion distribution across disease types and across lesion types. These findings of distinct lesion distributions across patient subgroups and lesion types suggest that different subtypes of pathology exist in MS based at least in part on different immunological mechanisms. For example, periventricular predilection of MS lesions may be caused at least in part by differences in the vasculature compared to other regions, making this location vulnerable to pathological changes. Without wishing to be bound by any theory, enhanced lesions in peripheral as opposed to central brain regions may be caused, at least in part, by central lesions developing from progressive gliosis and peripheral lesions being more inflammatory. As lesions in different locations may have different immunological backgrounds, they may warrant different treatment mechanisms. Results described herein suggest that differences in immunological backgrounds of lesion formation among MS patients may be driven by genetic predisposition.
Aspects of the invention relate to a large-scale study investigating the genetic influences on different phenotypes of MS (disease severity, subtype, MRI characteristics, response to treatment). Described herein is an investigation into the correlation between genetic background and spatial lesion distribution in a large cohort of MS patients using a variety of SNPs.
Aspects of the invention relate to evaluating the severity of MS in a patient. One symptom associated with MS is the presence of demyelination (lesions or plaques) in the brain and/or spinal cord of a patient. It should be appreciated that regions of demyelination may be detected through any means known to one of ordinary skill in the art. In some embodiments, lesions are detected through MRI. In some embodiments treatment decisions regarding a patient with MS, are based on the occurrence of relapses and the development of white matter lesions visible on MRI. Brain lesion volume and distribution, however, are highly variable among MS patients and correlate only moderately with disability. Treatment guidelines would benefit from a better understanding of this variability. Differences in genetic background may lead to different lesion distribution, which in turn may lead to a different clinical expression of the disease. Thus, the correlations revealed herein, between the presence of specific genetic markers and the presence of lesions offer important applications for screening of patients who have or are at risk of MS, diagnostic and prognostics for MS patients, as well as development of appropriate therapeutic approaches. As used herein, the term disease severity refers to the evaluation of a patient's disability using the tests listed above or other similar tests known in the art. An assessment of disease severity in some embodiments includes determining rapidity of development of disability, disease duration, rate of progression or relapse of symptoms, and symptoms such as changes in sensation, fatigue, pain, muscle weakness and/or spasm, problems in speech, visual problems, difficulty in moving, difficulties with coordination and balance, bladder and bowel difficulties and cognitive impairment.
Several methods have been established for assessing the severity of MS based on analysis of clinical factors such as those in Table 2, below. Non-limiting examples of tests used to assess the severity of MS include the Kurtzke Expanded Disability Status Scale (EDSS), the Multiple Sclerosis Functional Composite measure (MSFC), and the Multiple Sclerosis Severity Score (MSSS). The MSSS test relates scores on the Expanded Disability Status Scale (EDSS) to the distribution of disability in patients with comparable disease durations. Effectively the MSSS assigns to each EDSS its median decile score within this distribution. For example, an MSSS of 5.0 indicates the disease is progressing at the median rate. A patient whose MSSS is 9.0 is a fast progressor, progressing faster than 90% of patients. A patient whose MSSS is 1.0 is a slow progressor, progressing faster than just 10% of patients. In some embodiments, based on the MSSS test a patient may be assigned a median docile score of 1, 2, 3, 4, 5, 6, 7, 8, 9, or 9.5, including any intermediate values. In some embodiments, based on a test such as the MSSS test, MS patients are allocated into severe and benign subgroups. In some embodiments, MS patients are classified into different categories of severity based on a test such as MSSS. In some embodiments MS patient may be classified as relapsing-remitting (RRMS), secondary progressive MS (SPMS), and primary progressive MS (PPMS).
The invention in one aspect presents a model for assessing the strength of the disability, or the severity of the form of MS, according to the MSSS scale, using SNP analysis, thus allowing differential treatment management for a given patient. Results described herein generate a model from the analysis of 605 MS patients and 700 MS patients (see Example section). In some aspects, the invention evaluates differences between patients that have an MSSS score of less than 2.5 versus patients that have an MSSS score 2.5 or greater. Aspects of the invention relate to using genetic markers that are correlated to certain degrees of MS severity as predictive of MS severity and as indicators of recommended therapeutic approaches. In some embodiments, methods described herein relate to screening a patient for one or more risk factors associated with MS. In some embodiments the presence of two or more of the SNPs described herein indicate a more severe form of MS.
The invention in one aspect relates to correlating specific SNPs or combinations of SNPs with the presence and/or severity of lesions in the brain and/or spinal cord. The SNPs or combinations of SNPs that are correlated to the presence and/or severity of lesions in the brain and/or spinal cord can be used as predictive, diagnostic or prognostic indicators of the presence and/or severity of lesions in the brain and/or spinal cord. The detection of such SNPs, indicating the presence of lesions in the brain and/or spinal cord may in some embodiments be used as an indicator of the severity of MS.
Aspects of the invention relate to determining the presence of SNPs through obtaining a patient DNA sample and evaluating the patient sample for the presence of two or more SNPs. It should be appreciated that a patient DNA sample can be extracted, and a SNP can be detected in the sample, through any means known to one of ordinary skill in art. Some non-limiting examples of known techniques include detection via restriction fragment length polymorphism (RFLP) analysis, planar microarrays, bead arrays, sequencing, single strand conformation polymorphism analysis (SSCP), chemical cleavage of mismatch (CCM), and denaturing high performance liquid chromatography (DHPLC).
In some embodiments, a SNP is detected through PCR amplification and sequencing of the DNA region comprising the SNP. In some embodiments SNPs are detected using microarrays. Microarrays for detection of genetic polymorphisms, changes or mutations (in general, genetic variations) such as a SNP in a DNA sequence, comprise a solid surface, typically glass, on which a high number of genetic sequences are deposited (the probes), complementary to the genetic variations to be studied. Using standard robotic printers to apply probes to the array a high density of individual probe features can be obtained, for example probe densities of 600 features per cm2 or more can be typically achieved. The positioning of probes on an array is precisely controlled by the printing device (robot, inkjet printer, photolithographic mask etc) and probes are aligned in a grid. The organisation of probes on the array facilitates the subsequent identification of specific probe-target interactions. Additionally it is common, but not necessary, to divide the array features into smaller sectors, also grid-shaped, that are subsequently referred to as sub-arrays. Sub-arrays typically comprise 32 individual probe features although lower (e.g. 16) or higher (e.g. 64 or more) features can comprise each subarray.
In some embodiments, detection of genetic variation such as the presence of a SNP involves hybridization to sequences which specifically recognize the normal and the mutant allele in a fragment of DNA derived from a test sample. Typically, the fragment has been amplified, e.g. by using the polymerase chain reaction (PCR), and labelled e.g. with a fluorescent molecule. A laser can be used to detect bound labelled fragments on the chip and thus an individual who is homozygous for the normal allele can be specifically distinguished from heterozygous individuals (in the case of autosomal dominant conditions then these individuals are referred to as carriers) or those who are homozygous for the mutant allele. In some embodiments, the amplification reaction and/or extension reaction is carried out on the microarray or bead itself.
In some embodiments, methods described herein may involve hybridization. For differential hybridization based methods there are a number of methods for analysing hybridization data for genotyping:
Increase in hybridization level: The hybridization levels of probes complementary to the normal and mutant alleles are compared.
Decrease in hybridization level: Differences in the sequence between a control sample and a test sample can be identified by a decrease in the hybridization level of the totally complementary oligonucleotides with a reference sequence. A loss approximating 100% is produced in mutant homozygous individuals while there is only an approximately 50% loss in heterozygotes. In Microarrays for examining all the bases of a sequence of “n” nucleotides (“oligonucleotide”) of length in both strands, a minimum of “2n” oligonucleotides that overlap with the previous oligonucleotide in all the sequence except in the nucleotide are necessary. Typically the size of the oligonucleotides is about 25 nucleotides. However it should be appreciated that the oligonucleotide can be any length that is appropriate as would be understood by one of ordinary skill in the art. The increased number of oligonucleotides used to reconstruct the sequence reduces errors derived from fluctuation of the hybridization level. However, the exact change in sequence cannot be identified with this method; in some embodiments this method is combined with sequencing to identify the mutation.
Where amplification or extension is carried out on the microarray or bead itself, three methods are presented by way of example:
In the Minisequencing strategy, a mutation specific primer is fixed on the slide and after an extension reaction with fluorescent dideoxynucleotides, the image of the Microarray is captured with a scanner.
In the Primer extension strategy, two oligonucleotides are designed for detection of the wild type and mutant sequences respectively. The extension reaction is subsequently carried out with one fluorescently labelled nucleotide and the remaining nucleotides unlabelled. In either case the starting material can be either an RNA sample or a DNA product amplified by PCR.
In the Tag arrays strategy, an extension reaction is carried out in solution with specific primers, which carry a determined 5′ sequence or “tag”. The use of Microarrays with oligonucleotides complementary to these sequences or “tags” allows the capture of the resultant products of the extension. Examples of this include the high density Microarray “Flex-flex” (Affymetrix).
For cost-effective genetic diagnosis, in some embodiments, the need for amplification and purification reactions presents disadvantages for the on-chip or on-bead extension/amplification methods compared to the differential hybridization based methods. However the techniques may still be used to detect and diagnose conditions according to the invention.
Typically, Microarray or bead analysis is carried out using differential hybridization techniques. However, differential hybridization does not produce as high specificity or sensitivity as methods associated with amplification on glass slides. For this reason the development of mathematical algorithms, which increase specificity and sensitivity of the hybridization methodology, are needed (Cutler D J, Zwick M E, Carrasquillo M N, Yohn C T, Tobi K P, Kashuk C, Mathews D J, Shah N, Eichler E E, Warrington J A, Chakravarti A. Genome Research; 11:1913-1925 (2001). Methods of genotyping using microarrays and beads are known in the art.
Some non-limiting examples of genotyping and data analysis can be found in co-pending patent application U.S. Ser. No. 11/813,646 (WO 2006/075254), which is hereby incorporated by reference. In some embodiments the genotypes are determined as follows: The signal from the probes which detect the different genetic variations is determined with a scanner. The scanner software executes a function to subtract the local background noise from the absolute signal intensity value obtained for each probe. Next, the replicates for each of the 4 probes that are used to characterize each genetic variation are grouped. The average intensity value for each of 4 probes is calculated using the average collated from the replicates in order to identify abnormal values (outliers) that can be excluded from further consideration. Once the average intensity value for each of the probes is known then two ratios are calculated (ratio 1 and ratio 2):
wherein probe 1 detects (is capable of specifically hybridising to) genetic variation A (e.g. a normal allele), probe 2 detects (is capable of specifically hybridising to) genetic variation B (e.g. a mutant allele), probe 3 detects (is capable of specifically hybridising to) genetic variation A (e.g. a normal allele) and probe 4 detects (is capable of specifically hybridising to) genetic variation B (e.g. a mutant allele).
These ratios are substituted in three Fisher linear functions which characterize each one of the three possible genotypes:
The function which presents the highest absolute value determines the genotype of the patient.
The Fisher linear functions are obtained by analyzing 3 subjects for each of the three possible genotypes of the genetic variation (AA, AB, BB). With the results, ratios 1 and 2 are calculated for the SNPs analyzed and for the 3 subjects. These ratios are classification variables for the three groups to create the linear functions, with which the discriminatory capacity of the two pairs of designed probes is evaluated. If the discriminatory capacity is not 100%, the probes are redesigned. New subjects characterized for each of the three genotypes make up new ratios 1 and 2 to perfect the linear functions and in short, to improve the discriminatory capacity of the algorithm based on these three functions.
When using a fluorescent laser, to obtain reliable results it is preferable that ratios 1 and 2 are within the range of the ratios used to build the groups.
Again when a fluorescent scanner is used in the experiment, for a complete hybridization to be considered reliable preferably the ratio of probe fluorescence intensity to background noise of all the beads DNA array probes is above 15. Likewise, the average of all the ratios is preferably above 0.6 and the negative control is preferably less than or equal to 3 times the background noise.
In summary, four probes are presented in the hybridization analysis for detection of each mutation. Two of the probes detect one genetic variation (A) and the other two the other genetic variation (B). The examined base is located in the central position of the probes.
A subject homozygous for the genetic variation A will not show genetic variation B. Consequently, the probes which detect genetic variation B will show a hybridization signal significantly less than that shown by variation A and vice versa. In this case the ratios 1 and 2 will show 1 and the subjects will be assigned as homozygous AA by the software analysis.
On the other hand, a heterozygous subject for the determined genetic variation shows both the genetic variations. Therefore, the probes which detect them show an equivalent hybridization signal. The ratios 1 and 2 will show 0.5 and the subject will be assigned as heterozygous AB the software analysis as described.
In one aspect of the invention, DNA polymorphisms are selected based on their association with the etiology of MS, such as those shown in Table 1 below:
Each individual in the study population is tested to determine an outcome for each of the discriminating variables for the particular phenotype. This provides a number of outcomes for each individual. Testing, e.g. genotyping, may be carried out by any of the methods described herein, e.g. by microarray analysis as described herein. Testing is typically ex vivo, carried out on a suitable sample obtained from an individual.
Multiple genotype-phenotype associations may then be analysed using stepwise multivariate logistic regression analysis, using as the dependent variable the clinically determined MS phenotype and as independent variables the outcomes of the informative variables. The goodness of fit of the models obtained may be evaluated using Hosmer-Lemeshow statistics and their accuracy assessed by calculating the area under the curve (AUC) of the Receiver Operating Characteristic curve (ROC) with 95% confidence intervals (see, e.g. (Janssens A C J W et al., 2006)).
Mean probability function values for each of the alternative phenotypes in the population can be compared using a t test. In general the probability functions are able to distinguish between the different phenotypes in the study population in a statistically significant way, for example, at p≦0.05 in a t-test. Thus the probability functions produce a statistically significant separation between individuals of different phenotype in the population.
In some embodiments, the presence of two or more genetic markers in a sample from an MS patient is compared to the presence of two or more genetic markers in a control sample. In some embodiments a control sample is a sample from an individual who does not have MS. In other embodiments a control sample is a sample from an individual who has MS. In certain embodiments, a control sample is a sample from an individual who has MS of a specified classification or degree of severity. It will be understood that the interpretation of a comparison between a test sample and a control sample will depend on the nature of both samples. One possible measurement of the level of expression of genetic markers in a sample is the absolute number of genetic markers identified in a sample. Another measurement of the level of expression of genetic markers in a sample is a measurement of the specific combination of genetic markers in a sample.
In some embodiments, a control value may be a predetermined value, which can take a variety of forms. It can be a single cut-off value, such as a median or mean. It can be established based upon comparative groups, such as in groups not having MS, or groups have specified classifications or levels of severity of MS. For example, in some embodiments, a control sample that is taken from an individual who does not have MS, may be considered to exhibit control or normal patterns of expression of genetic markers for MS. In some embodiments where severity of MS is being assessed, a control sample that is taken from an individual that has a specified classification or level of severity of MS, such as a mild form of MS, may be considered to exhibit a normal or control pattern of expression of markers for MS. In some embodiments a control sample will be from an individual who is of the same ethnic background, gender, age, MS classification and/or MS disease duration as the individual who is being screened and/or diagnosed.
Based at least in part on results of correlations and methods discussed herein, predetermined values can be arranged. For example, test samples and subjects from which the samples were extracted can be divided into groups such as low-severity, medium-severity, and high-severity groups based on the presence of two or more genetic markers that are correlated to MS severity. In some embodiments the classification of a sample and subject into a group can be used to aid or assist in screening, diagnosis, prognosis or development of a treatment strategy for a given subject.
Described herein are correlations between the presence of specific genetic markers and the severity of symptoms of MS in a patient. Such correlations and methods for detecting such correlations have widespread applications for MS patients. In some embodiments methods described herein are used to screen patients who have or are at risk of having MS. In some embodiments, evaluation of the presence of two or more SNPs in a patient will be used to assist in the diagnosis or to indicate or evaluate the severity of MS in the patient. In some embodiments, genetic information obtained from methods described herein will be combined with other clinical data to assess the severity of MS in a given patient.
In some embodiments, the identification of two or more SNPs in a DNA sample from an MS patient will be used to initiate or change a treatment regimen for the patient. For example, in some embodiments, detection of two or more SNPs that are associated with increased severity of MS may cause a physician to change the treatment strategy of an MS patient in order to target a more severe form of the disease, or advise a patient that they may benefit from a change in treatment strategy. In some embodiments, detection of two or more SNPs that are associated with increased severity of MS may cause a physician to monitor an MS patient more closely or rigorously. In some embodiments, detection of two or more SNPs that are associated with increased severity of MS may cause a physician to recommend or advise that a patient undergo genetic counseling.
In some aspects of the invention measurement of clinical variables comprises part of the severity prediction model along with the genetic variables in Table 1, above. Some non-limiting examples are age at onset, gender of patient studied, and type of onset of the disease (e.g. progressive or relapsing) (see Table 2). Age at onset refers to the age in years at which the patient was diagnosed with MS. In the present models this measure has been treated as a continuous variable, which is included in the logistic regression function of the models. Thus an outcome for this variable is age of patient when diagnosed for MS.
Gender refers to the gender of the patient diagnosed with MS. In the present models this measure has been treated as a categorical variable, with levels “male” and “female”, which is included in the logistic regression function of the models. Thus an outcome for this variable is gender of patient diagnosed with MS. If the gender is male, this is coded as (1), and if the gender is female, this is coded as (0).
Type of onset refers to the type of onset of disease, progressive or relapsing, for the studied patient diagnosed with MS. In the present models this measure has been treated as a categorical variable, which is included in the logistic regression function of the models. Thus an outcome for this variable is age of patient when diagnosed for MS. If the type of onset is progressive, this is coded as (1), and if the type of onset is relapsing, this is coded as (0).
In embodiments comprising methods of evaluation of MS severity in a patient, the method typically comprises determining or obtaining for the subject, an outcome for each of the variables listed in Table 2. In some embodiments, use of the results of the measurements of these variables, along with the variables in Table 1, allows prognosis of MS severity phenotype in a Dutch population with an LR+ of 8.4. Details for the calculation of a probability function using these variables are given in Table 3.
Preferably the number and combination of variables such as SNPs used to construct a model for predicting a phenotype according to the invention, is such that the model allows prediction to be made with an LR+ value of at least 1.5, such as at least 2, 3, 4, 5, 6, 7, 8, 9, or 10. Calculation of LR+ values is described herein.
Once an outcome is determined for each of the variables for prediction of a given phenotype, these outcomes are used in or inserted in a suitable probability function (for prediction of that phenotype), as described herein and a probability function value is calculated. Outcomes may be codified for use in the probability function and calculation of the probability function value. The probability function value is then compared with probability function values obtained for a population of individuals of known (clinically determined) phenotype. The risk of the subject having or developing the particular phenotype is thereby determined.
The sensitivity, specificity, and positive likelihood ratio (LR+=sensitivity/(1−specificity)) may be computed by means of ROC curves. Preferably the model has an LR+ value of at least 1.5, for example, at least 2, 3, 4, 5, 6, 7, 8, 9 or 10.
Also within the scope of the invention are kits and instructions for their use. In some embodiments kits associated with the invention are kits for identifying two or more SNPs within a patient sample. In some embodiments a kit may contain primers for amplifying a specific genetic locus. In some embodiments, a kit may contain a probe for hybridizing to a specific SNP. A kit of the invention can include a description of use of the contents of the kit for participation in any biological or chemical mechanism disclosed herein. A kit can include instructions for use of the kit components alone or in combination with other methods or compositions for assisting in screening or diagnosing a sample and/or determining a treatment strategy for MS.
The kits described herein may also contain one or more containers, which may contain a composition and other ingredients as previously described. The kits also may contain instructions for mixing, diluting, and/or administering or applying the compositions of the invention in some cases. The kits also can include other containers with one or more solvents, surfactants, preservative and/or diluents (e.g., normal saline (0.9% NaCl), or 5% dextrose) as well as containers for mixing, diluting or administering the components in a sample or to a subject in need of such treatment.
The compositions of the kit may be provided as any suitable form, for example, as liquid solutions or as dried powders. When the composition (e.g., a primer) provided is a dry powder, the composition may be reconstituted by the addition of a suitable solvent, which may also be provided. In embodiments where liquid forms of the composition are used, the liquid form may be concentrated or ready to use. The solvent will depend on the composition and the mode of use or administration. Suitable solvents for drug compositions are well known, for example as previously described, and are available in the literature. The solvent will depend on the composition and the mode of use or administration.
As used herein, the term “subject” refers to a human or non-human mammal or animal. Non-human mammals include livestock animals, companion animals, laboratory animals, and non-human primates. Non-human subjects also specifically include, without limitation, chickens, horses, cows, pigs, goats, dogs, cats, guinea pigs, hamsters, mink, and rabbits. In some embodiments of the invention, a subject is a patient. As used herein, a “patient” refers to a subject who is under the care of a physician or other health care worker, including someone who has consulted with, received advice from or received a prescription or other recommendation from a physician or other health care worker. A patient is typically a subject having or at risk of having MS.
The term “treatment” or “treating” is intended to relate to prophylaxis, amelioration, prevention and/or cure of a condition (e.g., MS). Treatment after a condition (e.g., MS) has started aims to reduce, ameliorate or altogether eliminate the condition, and/or its associated symptoms, or prevent it from becoming worse. Treatment of subjects before a condition (e.g., MS) aims to reduce the risk of developing the condition and/or lessen its severity if the condition does develop. As used herein, the term “prevent” refers to the prophylactic treatment of a subject who is at risk of developing a condition (e.g., MS) resulting in a decrease in the probability that the subject will develop the disorder, and to the inhibition of further development of an already established disorder.
Treatment for MS varies with the stage of the disease and the clinical presentation of the patient. In general it is advantageous to begin treatment early in the course of the disease. Goals for treatment may include slowing the progression of the disease, reducing the number of the attacks, and improving recovery from attacks. Corticosteroids such as Methylprednisolone (Solu-Medrol®, Medrol, Depo-Medrol), and Prednisone (Deltasone®, Liquid Pred, Orasone, Prednicen-M) are used to treat exacerbations of MS. In some embodiments Methylpredisone is given intravenously for 2-7 days, followed by a course of Prednisone. Corticosteroids may be used only for very severe attacks, as the effects vary and there are numerous reported side effects.
In some embodiments an MS patient is treated with therapies that can modify the course of the disease. Certain immune modulatory therapies are thought to slow the progression of MS by tempering the immune system's attack on the central nervous system. Some non-limiting examples include Interferon beta-1a, Interferon beta-1b, and Glatiramer acetate. Some examples of Interferon beta-1a include Avonex® and Rebif®. Avonex® is typically administered by intramuscular injection once weekly, whereas Rebif® is typically administered subcutaneously 3 times per week, at a dose of 22 or 44 mcg. Interferon beta-1b, e.g. Betaseron, is in some embodiments given by subcutaneous injection ever other day. Patients treated with interferon may experience fewer relapses or faster recovery from attacks, and an overall slowing of the progression of the disease. Glatiramer acetate, e.g. Copaxone®, is a synthetic amino acid that modifies actions of the immune system that may affect the progression of MS. It has been shown to reduce the frequency of exacerbations and the level of disability. In some embodiments this medication is given subcutaneously daily.
Other immune modulatory therapies include Natalizumab (Tysabri®), a monoclonal antibody against VLA-4, Mitoxantrone (Novantrone®), a chemotherapy drug. Natalizumab is administered via monthly intravenous injections and has been shown to reduce the frequency of clinical relapses and delay the progression of physical disability. Mitoxantrone is used for reducing neurologic disability and/or the frequency of clinical relapses. In some embodiments vitamin D is used as a treatment.
Other treatments for relief from complications of the disease are aimed at specific to symptoms, such as muscle spasticity, weakness, eye problems, fatigue, emotional outbursts, pain, bladder dysfunction, constipation, sexual dysfunction, and tremors.
In multiple sclerosis (MS), the total volume of spinal and brain lesions and their spatial distribution are highly variable. Elucidating this variability may contribute to understanding clinical heterogeneity in MS.
Study Participants:
Patients were selected retrospectively from natural history studies conducted at the
MS Center at the VU University Medical Center in Amsterdam. Patients were selected for the availability of DNA material, as well as spinal cord and brain MRI, which fulfilled certain standardization requirements and were performed less than two years apart. The study was carried out with the approval of the Medical Ethical Committee of the VUmc and informed consent was obtained from all participants. Patients, all diagnosed with MS ascertained by Poser or McDonald criteria (Poser et al., Ann. Neurol 1983; 3:227-231; Polman C H et al., Ann. Neurol. 2005; 6:840-846). For the patients included in the analysis, clinical data were collected including age, gender, type of disease onset, age at onset, disease course and duration of disease. Disability status was determined for all subjects by using Kurtzke's Expanded Disability Status Scale (EDSS) and when available Multiple Sclerosis Functional Composite scale (MSFC).
Selection of SNPs:
Polymorphisms were selected based on published involvement in MS pathogenesis, prognosis and response to treatment. The polymorphisms were confirmed and associated to an identifier by using dbsnp database (www.ncbi.nlm.nih.gov/SNP). Nucleotide sequences for the design of allele-specific probes and PCR primers where retrieved in the SNPper database (http://snpper.chip.org/bio). Sequence specific probes and primers were designed by using the software Primer3 freely available at http://frodo.wi.mit.edu/. Some non-limiting examples of probes and primers useful in the instant invention can be found in Tables 7-9.
If a polymorphism was not present in the database, position and sequences were established by performing a blast search (http://www.ncbi.nlm.nih.gov.catalog.llu.edu/BLAST/) using the data available in the literature.
Genotyping
Genomic DNA was isolated from anti-coagulated blood with DNAzo1 reagent (Molecular Research Center, Inc., Cincinnati, Ohio).
Genotyping was carried out using a newly developed low-density DNA microarray based on allele-specific probes. The design, fabrication, validation and analysis of the arrays were performed following the procedure described by Tejedor et al. (2005), Clin. Chem., Vol. 51(7), pp. 1137-1144, with minor modifications.
Brain MRI
Scans were acquired either on 1.0 Tesla or 1.5 Tesla (Siemens) scanners with standard head coils, using standard 2D conventional or fast spin-echo PD- and T2-weighted images (TR: 2200-3000 ms, TE: 20-30 & 80-100 ms) with a slice thicknesses of 3-5 mm, a maximum gap between slices of 0.5 mm, and an in-plane resolution of 1×1 mm2. Lesions were identified by an expert reader and then outlined on the corresponding PD image using home-developed semi-automated seed-growing software based on a local thresholding technique. Lesion areas were multiplied with the interslice distance to obtain total T2 brain lesion volume for each patient.
Spinal Cord MRI:
Spinal cord scanning included a cardiac-triggered sagittal PD and T2-weighted dual-echo spin echo sequence with a slice-thickness of 3 mm covering the whole spinal cord (TR: 2500-3000 ms, TE: 20-30 & 80-100 ms) with an in plane resolution of 1×1 mm. From this sequence the number of focal abnormalities and the presence of diffuse abnormalities were scored by one experienced reader (CL). Diffuse abnormalities were defined as areas with poorly delineated areas of increased signal intensity compared to signal intensity of spinal CSF on intermediate-weighted images.
Statistical Methods for MRI Data:
First the association between the brain parameter (T2 lesion load) and spinal cord parameters (number of focal lesions, presence of diffuse abnormalities) were tested per SNP and per clinical variable. The non-parametric Kruskal-Wallis test and ChiSquare test were used appropriately, applying the False Discovery Rate (FDR) according to Benjamini and Hochberg (Benjamini, Y, 1995, J. R. Stat. Soc. B Met 289) to correct for multiple testing. The corrected number represents the expected proportion false discoveries for a given p-value cut-off. The cut-off point after FDR correction of p<0.05 was used. Pearson's correlation coefficient was used to test the correlations between two scaled variables. All analyses were performed using SPSS (version 15; SPSS Inc., Chicago, Ill., USA).
Statistical Methods for Regression and Association Analysis:
First the association between MS severity score, the brain parameter (T2 lesion load) and spinal cord parameters (number of focal lesions, presence of diffuse abnormalities) were tested per SNP and per clinical variable and statistically significant associations between particular genotypes and particular phenotypes are identified. Methods for determining statistical significance are known in the art. Models were created by means of multivariate logistic and/or linear regression, for categorical or continuous dependent variables respectively, with clinically determined disease phenotypes as dependent variables and the SNPs and clinical variables as independent variables or regressors. To evaluate the impact of the regressors included in the prognosis of the analysed phenotypes, the sensitivity, specificity and positive likelihood ratio (LR+=sensitivity/(1−specificity)) were computed by means of Receiver Operating Characteristic curves. In the case of multiple linear regression, the impact of the regressors the corrected R square was computed. All analyses were performed using the Statistical Package for the Social Sciences (SPSS) version 15 and HelixTree (Golden Helix, Inc., Bozeman, Mont.).
The invention presents a model for predicting the probability of having a stronger disability, as measured by the MSSS scale, thus allowing differential treatment management for a given patient. This model was obtained from the analysis of 605 MS patients. The invention evaluates differences between patients that have an MSSS score of less than 2.5 versus patients that have an MSSS score of 2.5 or greater.
Table 3 (shown below) shows the six SNPs (rs876493, rs1137933, rs1318, rs2069763, rs2107538 and 2073 Intron2 C/T (rs423904)) with the associated genotypes and the three clinical variables (age at onset, gender and onset type) and the associated levels, together with their significance (Sig.), the coefficients in the model (B) and their odds ratios (OR) with lower and upper bound confidence intervals (I.C 95.0% for OR) used to compute the model for the prediction of the MSSS<2.5 versus≧2.5 phenotype. This model provides the probability to develop a severe form of MS.
Additional MS patients have been recruited increasing the MS cohort to 700 MS patients. In a first stage of analysis, feature selection was employed to identify the most important and predictive features in the model to be analyzed. This approach of variable filtering is based on the marginal association between each variable (SNP or clinical variable) and phenotype, as variables are typically filtered on the basis of a p-value cut-off from a univariate analysis. For the selection of variables, HelixTree® software (Golden Helix, Inc., Bozeman, Mont., USA) was used to calculate allelic association between different groups. In Table 3A, SNPs associated with MSSS score at a significance level of p<0.1 set as the decision threshold are shown.
A Multivariate prognostic model was then constructed for dichotomous MSSS with the cut-off point of 2.5 using logistic regression model, using SPSS version 15.0 (SPSS Inc. Headquarters, Chicago, Ill., USA) and R packages Design (Harrell, 2001) and Stats (R Development Core Team, 2008). The model was developed including information for the clinical variables available.
85% of the cohort was selected at random as exploratory cohort (n=595) and the 15% of the cohort as replication cohort (n=105). The model obtained with the exploratory cohort (Table 3B) included the same variables as the one obtained from the analysis of 605 MS patients (Table 3). The model showed in Table 3B was validated in the replication cohort (AUC exploratory cohort=0.743 (0.691-0.796) (
The model obtained from the analysis of the 700 MS patients is showed in Table 3C. The model includes the same variables that the obtained from the analysis of 605 MS patients (Table 3) and from the analysis of the exploratory cohort or 595 MS patients (Table 3B).
The ROC curve area obtained for the model MSSS≧2.5 vs MSSS<2.5 analysing the 700 MS patients is 0.749 (95% CI 0.700-0.797) (
In order to determine whether certain SNPs are associated with increasing size and distribution of T2 brain lesions, analysis was performed on a group of 208 MS patients with MRI data collected. The MRI data show spatial distribution of T2 brain lesions.
Further investigation was carried out essentially as described in Example 2. Additionally, lesions were manually outlined on Magnetic Resonance Imaging scans and binary lesion masks were produced and registered to a common space. Using Randomise software, the lesion masks were related to genotype using a voxelwise nonparametric General Linear Model approach, followed by clusterwise analysis. The results show significant associations for eight SNPs to brain lesions: rs9808753 (IFNGR2 gene), rs2074897 (NDUFS7 gene), rs762550 (CRYAB gene), rs2076530 (BTNL2 gene), rs2234978 (FAS gene), rs3781202 (FAS gene), rs2107538 (CCL5 gene), rs659366 (UCP2 gene).
Patient Characteristics:
One hundred and fifty patients were included in the analysis. The patient group reflects a representative MS population, with approximately 35% men and 20% primary progressive MS patients (see Table 4). The majority of patients (132/150) demonstrated abnormalities on the spinal cord MRI scan, while all patients had abnormalities on the brain MRI scan.
Genotyping:
In total 80 SNPs in 44 genes were selected on the MSchip. Twelve SNPs were excluded from further analysis: five were monomorphic and seven SNPs had a minor allele frequency below five percent (see Table). Hardy Weinberg equilibrium was calculated for all SNPs. Values are noted in table 5.
Correlation Between Clinical Parameters and MRI Features:
The EDSS showed a mild correlation with the number of focal lesions in the spinal cord (p=0.043, r=0.165, Pearson correlation), with the number of segments involved (p=0.006, r=0.224, Pearson correlation) and a moderate correlation with T2 lesion load in the brain (p<0.001, r=0.395). A weak correlation was present between the number of focal spinal cord lesions and T2 lesion load in the brain (p=0.063, r=0.152).
Disease duration was found to be related to number of segments of the spinal cord involved (p=0.017, r=0.195).
The T2 lesion load in the brain was closely related to the PASAT score (p=0.000, r=−0.581) and 9 Hole Peg Test of the dominant hand (p=0.001, r=0.306).
Correlation Between Lesion Load in the Brain and Genotypes:
In the univariate analysis on T2 lesion load in the brain and the MS-chip, the only ‘trend’ correlation was rs2107538 (CCL5) (see Table 5).
Correlation Between Spinal Cord Abnormalities and Genotypes:
Several HLA SNPs were found to be related to the number of focal spinal cord abnormalities (see Table 5). The most significant is SNP rs3135388. Carriership of the A-allele (surrogate marker for HLA-DRB1*1501) was associated with a significantly higher number of lesions in the spinal cord (
When corrected for multiple testing, five SNPs within the MHC region (rs3135388, rs2395182, rs2239802, rs2227139 and rs2213584), remained significant and one SNP within the MHC-2TA gene (Major Histocompatibility Complex Class II Transactivator) showed a trend towards a correlation. The five HLA SNPs are in high linkage disequilibrium.
A linear model has been developed using multiple linear regression to predict the number of focal lesions in the spinal cord. This method uses three of these SNPs rs3135388, rs3087456, and rs2227139. A model including the combination of these three SNPs improves the use of one single SNP (rs3135388) for prediction of number of focal lesions in the spinal cord. Corrected Rsquared for model using only one SNP=0.064. Corrected Rsquared for model using combination of three SNPs=0.112. The combination of these three SNPs or any SNP in linkage disequilibrium with any of these three SNPs improves prediction of number of focal lesions in the spinal cord over the use of one single SNP.
No interactions between the SNPs and the clinical variables were present. No association was observed between the presence of diffuse abnormalities and the evaluated SNPs.
In order to determine whether certain additional SNPs are associated with MRI parameters, a similar analysis to Example 3 was performed using different SNPs on one hundred and fifty patients. Results of the correlation of additional SNPs and MRI parameters are shown in table 5A.
In our study cohort of 150 MS patients with MRI data, MRI data are significantly correlated with MS severity given by MSSS (p=0.023). It can thus be assumed that identification of SNPs associated with MRI parameters allows inferring MS severity.
Table 10 shows SNPs and associated risk alleles for MS disease severity. Presence of one or more risk alleles as indicated in Table 10 at the specified SNPs is associated with a higher probability that the subject has a greater severity of MS disease phenotype, for example: a multiple sclerosis severity score (MSSS) of 2.5 or greater; an increase in size and/or distribution of T2 brain lesions; an increased number of focal lesions in the spinal cord; an increased T2 lesion load in the brain; and/or the presence of diffuse abnormalities in the spinal cord.
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The foregoing written specification is considered to be sufficient to enable one skilled in the art to practice the invention. The present invention is not to be limited in scope by examples provided, since the examples are intended as a single illustration of one aspect of the invention and other functionally equivalent embodiments are within the scope of the invention. Various modifications of the invention in addition to those shown and described herein will become apparent to those skilled in the art from the foregoing description and fall within the scope of the appended claims. The advantages and objects of the invention are not necessarily encompassed by each embodiment of the invention.
All references, including patent documents, disclosed herein are incorporated by reference in their entirety, particularly for the disclosure referenced herein.
This is the U.S. National Stage of International Application No. PCT/GB2010/000466, filed Mar. 12, 2010, which was published in English under PCT Article 21(2), which in turn claims the benefit of U.S. Provisional Application No. 61/210,124, filed Mar. 12, 2009, which is incorporated herein in its entirety.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/GB2010/000466 | 3/12/2010 | WO | 00 | 11/23/2011 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2010/103292 | 9/16/2010 | WO | A |
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| 20040091915 | Comings et al. | May 2004 | A1 |
| 20060240463 | Lancet et al. | Oct 2006 | A1 |
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| WO 03095618 | Nov 2003 | WO |
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| WO 2008010082 | Jan 2008 | WO |
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