Oscar winner Natalie Portman and other pregnant women may glow with hormones. But to-be-mamas lose some of that radiance at the thought of having a long needle dig into their bellies to check their unborn baby for Down syndrome. Now thanks to some intrepid researchers, pregnant women might be able to ditch the stressful prenatal screens all together thanks to DNA methylation.
Prenatal diagnosis methods for Downs, such as amniocentesis and chorionic villus sampling (CVS), are invasive, increase risks of miscarriage, and just plain stressful. Researchers know there are methylation differences between the mom and baby’s DNA and have identified differentially methylated regions (DMRs). So a team led by Philippos Patsalis at The Cyprus Institute of Neurology and Genetics figured out how to put those DMRs to good use in a prenatal screening cocktail for Down syndrome. The team:
- Enriched the free fetal DNA by MeDiP, which immunoprecipitates methylated DNA with an antibody that specifically recognizes 5’-methylcytosine, then
- Assayed a subset of DMRs on the fetal chromosome 21 with real-time quantitative PCR, then
- Determined the DNA methylation ratio, which is characteristic for normal and trisomy 21 cases.
- Showed that a combination of eight specific DMRs out of twelve, and not a single DMR, gave an accurate diagnosis of fourteen trisomy 21 and twenty-six normal cases.
This makes the approach really attractive as a noninvasive prenatal diagnostic test for Down syndrome and perhaps even other chromosomal disorders.
To dig deeper into the details, click over to the February 2011 issue of Nature Medicine