Non-invasive prenatal determination of fetal sex using cell-free fetal DNA provides an alternative to invasive techniques for some heritable disorders. New research revealed that widely available blood tests that predict gender are extremely accurate. Furthermore, the tests work more than seven months before the baby is born. The Tufts University study was published in the “Journal of the American Medical Association”.

From 57 selected studies, 80 data sets (representing 3524 male-bearing pregnancies and 3017 female-bearing pregnancies) were analyzed.  The researchers used a real-time quantitative PCR to detect Y chromosome sequences in the maternal bloodstream. 

The study found that the test was 95% accurate in women who were at least 7 weeks pregnant. Amniocentesis and ultrasounds, traditional tests used to determine a baby's gender, are accurate only later, researchers said. Also, sensitivity and specificity for detection of Y chromosome sequences was 99% after 20 weeks' gestation.

The researchers also said the blood test may be a breakthrough for women at risk of having babies with sex-linked hereditary diseases. These women can now avoid invasive procedures used to determine gender in early pregnancy.

JAMA, 2011, 306(6):627-636

Results were available from 753 pregnancies with the 8-plex sequencing protocol and from 314 pregnancies with the 2-plex protocol. The performance of the 2-plex protocol was superior to that of the 8-plex protocol. With the 2-plex protocol, trisomy 21 fetuses were detected at 100% sensitivity and 97.9% specificity, which resulted in a positive predictive value of 96.6% and negative predictive value of 100%. The 8-plex protocol detected 79.1% of the trisomy 21 fetuses and 98.9% specificity, giving a positive predictive value of 91.9% and negative predictive value of 96.9%.

Conclusion: Multiplexed maternal plasma DNA sequencing analysis could be used to rule out fetal trisomy 21 among high risk pregnancies. If referrals for amniocentesis or chorionic villus sampling were based on the sequencing test results, about 98% of the invasive diagnostic procedures could be avoided.

 BMJ 2011; 342:c7401  (Published 11 January 2011)
 

The current available techniques for prenatal diagnosis (CVS and amniocentesis) are invasive and carry with their use a small but significant chance of miscarriage. As a result, the current standard care offers an invasive prenatal gender test only to those women whose risk of chromosomal or genetic abnormalities are greater than or equal to the risk of a procedure-related loss. This means that the vast majority of women never receive the benefits of a gender test prediction. The recent discovery of the presence of fetal genetic material in maternal blood has offered new approaches to non-invasive prenatal diagnosis. The concentration of fetal DNA in maternal blood was found to be much higher than that present in the cellular fraction. Given the relatively easy identification of male DNA in maternal blood, one clinical application is the non-invasive identification of male fetuses at risk for X-linked disorders. The second is a curiosity application for the parents who would like to know the gender of the baby. This webpage explains in details how and when you can do the non-invasive prenatal gender test.

Advantages of fetal DNA analysis in maternal blood

1. Analysis of fetal DNA and fetal cells in maternal blood samples is a screening test that is a non-invasive prenatal procedure and poses no risks to the mother or the fetus. The non-invasive baby gender predictor is based on the detection of Y chromosome-specific DNA in maternal blood samples.

2. This DNA identity baby gender test is relatively inexpensive in comparison to invasive techniques such as CVS or amniocentesis.

To learn more, read Misconceptions about the technology and an article in the Science magazine about the non-invasive prenatal technology.

Timing for the test

Using DNA test from Health Genetic Center, a gender confirmation (Y-chromosome detection) can be done at 10 weeks of gestation.

Results

The procedure takes 7 business days, and the final report contains one of the following results:

- POSITIVE for the presence of Y-chromosome. Positive Y chromosome DNA test confirms the presence of a male fetus in the recent pregnancy.

- NEGATIVE for the presence of Y-chromosome. Negative DNA test result confirms the absence of Y chromosome DNA in maternal blood samples. This means that 1) the mother is carrying a female fetus or 2) amount of fetal DNA in maternal blood is very low (lower than the detection limit of the DNA test). Please note that if the sample is collected after 10 weeks of pregnancy then the technique is sensitive enough to detect a small amount of fetal DNA in mother’s blood. Only in very rare cases (less than 1%) this amount lower is than the detection limit at 10 weeks of pregnancy.

Sensitivity and specificity of the test

Sensitivity and specificity of the detection of male fetuses at 10 weeks of gestation for properly collected maternal blood samples is more than 99%.

Price for the Prenatal Gender Test

Total price of laboratory DNA testing for baby gender test determination is $390.00 (US). The cost includes the diagnostic laboratory test, telephone consultations, sample collection kit, and final laboratory report. Please make sure the payment for the DNA baby gender test is included in the form of money order, VISA, Master Card or American Express. A non-refundable deposit of $100.00 is required to initiate the scheduling process and will be applied towards the case. The balance must be paid in full before we can release the DNA gender test results. All prices are in US dollars.

Prenatal diagnosis to check for chromosome abnormalities and genetic diseases is common. Doctors capture fetal cells for DNA analysis using amniocentesis, which taps some of the fluid in the womb, or chorionic villus sampling, which plucks a snippet of tissue from the placenta. Although safe, both tests slightly raise the chances of a miscarriage, spurring researchers to look for alternatives. In 1997, chemical pathologist Y. M. Dennis Lo, now at the Chinese University of Hong Kong, and colleagues discovered a rich vein of fetal DNA in, well, the mother's veins. About 10% of the DNA fragments floating in the mother's blood comes from the fetus, from dying placental or fetal cells. Clinical tests capitalize on this DNA to discern the baby's sex and determine whether mother and child have incompatible Rh blood groups, which can lead to fatal complications. But the difficulty of distinguishing maternal DNA from fetal DNA has prevented researchers from developing tests to test for most other genetic conditions.

To overcome this problem, Lo and colleagues applied cutting-edge DNA-sequencing techniques, which can rapidly sequence large amounts of DNA, to the billions of DNA fragments in a blood sample from a pregnant woman. Using DNA samples from a woman and her husband, the team analyzed approximately 900,000 single-nucleotide polymorphisms, one-letter changes in the genetic code that reveal where the DNA of the parents differs. With this information, the researchers first determined that the mother's blood carries all of the fetus's genome and which DNA the baby inherited from each parent.

The team then tested the approach on a pregnant women at an obstetric clinic. The woman and her partner each carried a faulty copy of the gene for one part of hemoglobin, which predisposed her fetus to ß-thalassemia, which can lead to severe anemia. The team's tests showed that the baby didn't have ß-thalassemia but was a carrier, receiving a mutated version of the gene from the father and a normal one from the mother. Analysis of the baby's DNA obtained by chorionic villus sampling, which the mother had also undergone, confirmed the diagnosis. "We have worked out the principle and achieved the first noninvasive genetic scan of a fetus from the mother's blood," says Lo, whose team reports its findings online in “Science Translational Medicine”.

Several obstacles stand in the way of widespread use of fetal DNA analysis, however. For one, the type of DNA sequencing used in the study is too expensive for clinical testing, although most researchers expect its cost to plummet in the next few years. The results are also very complex and hard to interpret, notes reproductive geneticist Diana Bianchi of Tufts University School of Medicine in Boston. "It's a brilliant proof-of-principle study, but it's not ready for clinical application."

Still, many researchers are impressed. "I think it's a beautiful piece of work," says molecular geneticist Arthur Beaudet of Baylor College of Medicine in Houston, Texas. "It's an important step in the direction of showing the capability of this approach," adds Mark Evans, an obstetrician- gynecologist and geneticist at the Mount Sinai School of Medicine in New York City. Molecular biologist Sinuhe Hahn of University Women's Hospital in Basel, Switzerland, says that the approach should allow fetal DNA testing for a variety of other genetic diseases, such as cystic fibrosis and Tay-Sachs disease. "In essence, you have the entire genome of the fetus at your disposal."

(by Mitch Leslie on 8 December 2010, Science NOW.)

Advantages of fetal DNA analysis in the maternal blood

1. Analysis of fetal DNA and fetal cells in maternal blood samples is a screening test that is a non-invasive prenatal procedure and poses no risks to the mother or the fetus. The non-invasive prenatal DNA paternity testing is based on the comparison of genetic profiles of the fetal DNA, mother's blood and samples from the alleged father(s).

2. This prenatal non-invasive DNA paternity testing is relatively inexpensive in comparison to invasive techniques such as CVS or amniocentesis. To learn more, read Misconceptions about the technology and read an article in the Science magazine about the non-invasive prenatal technology.

Timing for the test

Using DNA test from Prenatal Genetic Center, prenatal DNA paternity can be performed after the 14th week of gestation.

Results

The procedure takes on average 9 business days, and the report contains one of the following results:

- The Alleged Father cannot be excluded as the biological father of the fetus based on the samples submitted from the mother and the alleged father and the DNA extracted from the population of fetal cells;

- The Alleged Father is excluded as the biological father of the fetus based on the samples submitted from the mother and the alleged father and the DNA extracted from the population of fetal cells.

Sensitivity and specificity of the test

Sensitivity and specificity of the detection of cell-free fetal DNA at 14 weeks of gestation for properly collected maternal blood samples is more than 99%. We strongly recommend testing all alleged fathers that are involved in your case (no extra charge for an additional alleged father).

Price for the prenatal DNA paternity test

Total price of laboratory DNA testing for the prenatal paternity test on blood is only $990.00. The cost includes a sample collection kit, the diagnostic laboratory tests for the mother and all alleged fathers, the laboratory reports a) for fetal DNA testing as well as b) free follow-up testing for a newborn child. Please make sure that the payment for the non-invasive prenatal paternity test is included in the form of money order, VISA, Master Card or American Express. A deposit of $200.00 is required to initiate the scheduling process and will be applied towards the case. The balance must be paid in full before we can release the DNA test results. All prices are in US dollars.

Benefits of doing non-invasive prenatal paternity testing with our laboratory

       Our laboratory is offering a full package for the our  clients:

a.     Free pretesting consultation for your case: explanation about prenatal testing; types of sample that can be collected from the alleged father(s) such as swab, hair, toothbrush and other samples; the best place and time to collect a blood sample from the mother; sending a sample collection kits to two different places (one for the mother and second for the alleged father) etc.

b.      No extra charge for an additional alleged father(s). We will test all alleged fathers that are involved in your case.

c.    Double DNA testing for the same child: the first test on fetal DNA extracted from maternal blood samples and the second test is a free follow-up test for a newborn child. Double DNA testing can give a double assurance to our clients: no uncertainties about the paternity of your child.

Full confidentiality of our testing: the mother can submit different samples from the alleged father(s) without asking him about. Our laboratory is accepting hair samples, toothbrushes, semen stain and other forensic samples collected from the alleged father.

Based on 11 years of our experience in non-invasive prenatal testing, our laboratory is offering more cost-effective (only $990 for a full package), less time consuming (on average 9 days for the test result) and simple to carry out (blood sample collection close to your place) prenatal paternity test.