Screening for trisomy 21, or Down Syndrome, is a terrifying experience for soon-to-be parents that’s made even worse by the anxiety of the invasive procedures used in today’s testing methods. Soon, though, new diagnostics based on epigenetic markers should be able to indicate prenatal trisomy 21 from just a bit of mom’s blood.
A new method developed at Wuhan University in China uses DNA methylation patterns to ID DNA floating in a mother’s blood stream as belonging to the fetus or mother, and then uses the fetal DNA to determine Down Syndrome. Here are a few of the highlights:
- Using MSP and MSRE + PCR, the Chinese team first determined that the AIRE and RASSF1A genes are hypomethylated in maternal DNA and hypermethylated in fetal DNA, allowing then to figure out which DNA in a blood sample is fetal.
- Since AIRE is located on chromosome 3, and RASSF1A on chromosome 21 their ratios can be used to calculate if trisomy 21 is present.
- This study looked at 388 pregnancies and found the differential DNA methylation patterns held true for about 97% of them.
- The new method identified 3 of 4 Down syndrome pregnancies in the group.
The Wuhan group also found that they got better results using MSRE + PCR than with MSP, probably because of bisulfite degradation in the relatively small amount of fetal DNA used.
Because of the small number of trisomy 21 pregnancies in their study, the scientists were unable to really dial in their method for that purpose, but they are convinced that its possible to use maternal blood samples for this kind of non-invasive, prenatal testing.
See the rest of the non-invasive details at Journal of Huazhong University of Science and Technology, November, 2011.