Patent Application
20090030723
The present invention relates to methods of genetic screening and analysis. More particularly, the present invention relates to a method of prenatal screening that generates a final prenatal risk factor (Rf) for genetic defects by integrating a patient's family history data (r1) with a patient's biological test data (r2p). A comprehensive risk factor (CRf) is generated by running a multiplicity of tests on the Rf that screens for various genetic disorders.
Generally, current methods of prenatal genetic analysis include amniocentesis or chorionic villus sampling (CVS) and karyotyping. Amniocentesis is a procedure that extracts a small amount of amniotic fluid from the amnion around a developing fetus. The amniotic fluid houses a source of fetal cells that can be readily separated from the amniotic fluid for analysis. The chromosomes of the fetal cells are analyzed for genetic abnormalities. Typically, an amniocentesis is performed between 15 and 20 weeks gestation, however early amniocenteses can be performed as early as 13 weeks gestation. Due to the invasive nature of amniocentesis testing, there are potential risks involved including the introduction of pathogens into the amniotic sac from the needle, or the puncture wound to the amniotic sac not healing properly, leading to infections or leakage. Genetic amniocentesis is generally restricted to being performed no later than the second trimester, and is not performed early in pregnancies because there is not an ample source of amniotic fluid when the fetus is young.
CVS is another method commonly used for prenatal genetic analysis. CVS requires performing genetics tests on a sample of chorionic villus or placental tissue. A CVS procedure can be preformed as early as 10-12 weeks, however it has been found to result in increased risks of miscarriages. Both amniocentesis and CVS are invasive procedures involving risks to both the women and the fetus.
Recently, less invasive procedures have become available to screen for genetic defects that involve sampling a pregnant woman's blood, serum, or urine to screen for abnormalities in the levels of specific proteins or hormones that have been linked to specific birth defects. Fetal ultrasound exams in the first or second trimester can screen for anomalies or soft markers associated with certain genetic disorders, but such exams are costly and yield lower detections and higher false positive test results. One of the drawbacks of current non-invasive methods is that the screening is specific to three chromosome disorders. For example, the new nuchal translucency measures the fluid accumulation at the back of the fetal neck, which has been shown to be a strong marker for chromosomal abnormalities, including Down syndrome, Trisomy 18, and Trisomy 13. Additionally, two biochemical pregnancy protein markers in maternal blood freeBeta hCG and pregnancy associated plasma protein A (PAPP-A) have recently been shown to be highly specific and sensitive for Down syndrome and Trisomy 18 and 13. Additionally early detection methods include combining blood and precise ultrasound measurements to improve non-invasive screening.
Unlike CVS or amniocentesis, the present invention does not diagnose prenatal conditions, but instead provides a risk estimate or probability of genetic disorders specific to each pregnancy, thereby reducing the need for follow-up procedures such as CVS or amniocentesis. Thus, the present invention provides increased risk assessment accuracy by integrating a patient's age and family history data with biological test sampling to produce a final risk assessment (Rf), in which the Rf is subsequently screened for a multiplicity of genetic disorders.
The present invention is provided to solve the problems discussed above and other problems, and to provide advantages and aspects not provided by prior genetic screening methods of this type. A full discussion of the features and advantages of the present invention is deferred to the following detailed description, which proceeds with reference to the accompanying drawings.
The present invention is directed to a method for genetic screening and analysis. The first aspect of the present invention is directed to a method of prenatal screening. The method comprises the steps of providing a first data set 10. The first data set 10 comprises patient data 12 of a patient. The patient data 12 is compared to a first standard 14 that provides a first risk factor (r1) 16 for genetic defects. The method further comprises providing a second data set 18. The second data set 18 comprises biological test data 20 from the patient. The biological test data 20 from the patient is compared to a second standard 22 that provides a second preliminary risk factor (r2p) 24 for genetic defects. The method further provides a final risk factor (Rf) 26 based upon an integration of r116 and r2p 24. Rf 26 provides increased accuracy prediction for genetic defects in a fetus of the patient.
In a second aspect of the claimed invention, the method of integrating r116 and r2p 24 is automated.
In another aspect of the claim invention a multiplicity of tests 28 are conducted on the Rf 26 to generate a comprehensive risk factor (CRf) 30 for determining risks for specific genetic defects.
Other features and advantages of the invention will be apparent from the following specification taken in conjunction with the following drawings.
To understand the present invention, it will now be described by way of example, with reference to the accompanying drawings in which:
While this invention is susceptible of embodiments in many different forms, there is shown in the drawings and will herein be described in detail preferred embodiments of the invention with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the broad aspect of the invention to the embodiments illustrated.
The present invention provides an improved method for screening prenatal genetic disorders by generating accurate and efficient risk assessments based on a multiplicity of factors. Furthermore, the present invention provides a method for a patient's fetus to be safely and accurately screened for potential risks of genetic disorders.
Referring now to the drawings in general, the illustrations are for the purpose of describing a preferred embodiment of the invention and are not intended to limit the invention thereto. As best seen in
The first data set 10 is compared to a first standard 14 that generates a first risk factor (r1) 16. In the preferred embodiment, the first standard 14 is the family history of a 35-year-old patient with no history of genetic defects. This biological standard is used to select patients as within normal range or at increased risk because their risk is lower or higher than the 35-year-old standard cutoff. Test results are calculated as a risk ratio, e.g. 1/100, with the same standard applying to all patients. The first risk factor (r1) 16 provides a risk assessment based only on a patient's family history and current physiological conditions.
As shown in the schematic of
As further shown in
One of the significant advantages of the method of the present invention is that testing is not restricted to a specific week during a patient's pregnancy. Since the method of the present invention is non-invasive, genetic screening can be conducted during an optimal week range appropriate for testing a specific risk factor, without putting the patient or fetus in danger. In a preferred embodiment, biological testing for freeBeta and PAPP-A are most effective at between about 24 and about 84 mm CRL, at 9 weeks, 1 day-13 weeks, 6 days. In another embodiment of the present invention, an automatic stop of the screening is triggered if the pregnancy is outside the appropriate week range to prevent human error and miscalculations of risk factors. For example, screening may be considered too early if a fetus' CRL is less than 24 mm. Alternatively, screening may be considered too late if a fetus' CRL is more than 84 mm.
In one embodiment of the present invention, a multiplicity of tests 28 is conducted on the Rf 26 to generate a comprehensive risk factor (CRf) 30 with increased accuracy for genetic detections. The multiplicity of tests 28 comprises a series of individual tests 34, r1mt, r2mt, r3mt, r4mt, r5mt, r6mt, r7mt etc., which screen for a specific genetic defect. The multiplicity of tests includes, but is not limited to, testing for Down syndrome, Trisomy 18/13, nasal bone defects, tricuspid flow defects, frontal maxillary angle defects, nuchal translucency, singletons, and monozygotic or dizygotic twins. Significantly, the method of the present invention allows simultaneous screening for multiple genetic disorders on the Rf 26. The screening method of the present invention provides patient's-specific risk for Trisomy 13 and Trisomy 18 rather than Trisomy 18 alone, detects about 40% of fetal heart defects, detects other types of fetal anomalies, and provides a risk estimation for some perinatal factors such as, but not limited to, pre-term delivery. Significantly, since the Rf 26 can be screened for numerous genetic abnormalities at once, without conducting separate, individual tests for each abnormality being screened, the present invention is more efficient and cost effective than previous prenatal genetic screening methods.
The following Table is a comparison of prenatal screening programs, including detection rates and screen positive rates for determining the weight of each risk factor. More weight is given for the more effective risk factors. Combining ultrasound measurements for Nuchal Translucency, dried blood freeBeta, and PAPP-A provide higher detection than older methods of screening for Down syndrome and Trisomy 18. Nasal bone or Tricuspid Flow can be added to increase detection by 4-5%.
While the specific embodiments have been illustrated and described, numerous modifications come to mind without significantly departing from the spirit of the invention, and the scope of protection is only limited by the scope of the accompanying Claims.
