New Noninvasive Method for Diagnosis of Trisomy 21

Fetal-specific DNA methylation ratio allows accurate prenatal diagnosis of trisomy 21

MONDAY, March 7 (HealthDay News) -- A combined approach using methylated DNA immunoprecipitation (MeDiP) and real-time quantitative PCR (qPCR) of maternal peripheral blood allows noninvasive prenatal diagnosis (NIPD) of trisomy 21 (Down's syndrome), according to research published online March 6 in Nature Medicine.

Elisavet A. Papageorgiou, Ph.D., from the Cyprus Institute of Neurology and Genetics in Nicosia, and colleagues evaluated the use of a noninvasive analysis of fetal-specific differentially methylated regions (DMRs) using combined MeDiP methodology and real-time qPCR to assess fetal chromosome dosage. Twelve fetal-specific DMRs (EP1 to EP12) in maternal peripheral blood samples from 20 normal and 20 trisomy 21 cases, and 40 blinded cases were analyzed.

The investigators found that, of the DMRs tested, EP1, EP4, EP7, and EP10 could discriminate between normal cases and trisomy 21 cases, but EP8 and EP11 could not. Using a combination of DMRs improved diagnostic sensitivity and specificity. Using this combined DMR approach all the known samples (20 normal and 20 trisomy 21) were correctly identified, and 26 normal and 14 trisomy 21 cases were correctly diagnosed in the blinded group.

"The approach described here has opened the way for NIPD of trisomy 21 to be potentially employed in the routine practice of all diagnostic laboratories and be applicable to all pregnancies," the authors write.

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