Multiplexed maternal plasma DNA to rule out trisomy 21

January 01, 0001

Multiplexed maternal plasma DNA to rule out trisomy 21

These Hong Kong, UK, and Netherlands researchers sought to validate the use of massively parallel maternal plasma DNA sequencing to screen for fetal trisomy 21 among high risk pregancies. They enrolled 753 pregnant women at high risk for fetal trisomy. DNA from maternal plasma was sequenced via two protocols: 2-plex and 8-plex sequencing. Results were validated against full karyotyping.

The researchers found: "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%."

The researchers concluded: "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."

This validation trial suggests an effective, non-invasive test to rule out trisomy 21.

For the full abstract, click here.

BMJ 342:c7401, 11 January 2011
© 2011 BMJ Publishing Group Ltd.
Non-invasive prenatal assessment of trisomy 21 by multiplexed maternal plasma DNA sequencing: large scale validity study. Rossa W K Chiu, Ranjit Akolekar, Yama W L Zheng, et al. Correspondence to Y M D Lo:

Category: W. Pregnancy, Family Planning. Keywords: DNA sequencing, trisomy 21, non-invasive testing, chorionic villus sampling, amniocentesis, validation study, journal watch.
Synopsis edited by Dr Paul Schaefer, Toledo, Ohio. Posted on Global Family Doctor 4 February 2011

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