In the news

To clinically validate prenatal screening for Down’s syndrome using measurement of circulating cell-free DNA in maternal plasma, to improve existing diagnostic procedures. 

A study was designed with a group of almost 5,000 pregnancies with high risk for Down’s syndrome based on maternal age, family history, positive serum analysis and/or sonographic screening.Maternal blood samples were drawn and sent to two independent, CLIA-certified laboratories for testing using the massively parallel shotgun sequencing method (MPSS). The results were compared to fetal karyotyping. 

Once compared to fetal karyotyping the Down syndrome detection rate was 98.6% and the false-positive rate was 0.20%. Testing failed only in 0.8% of pregnancies.  The cases were distributed evenly between the first and second trimester of pregnancy. 

In high-risk pregnancies, nearly all cases of Down syndrome can be detected from cell-free, maternal plasma DNA with a very low false-positive rate. This study provides evidence of clinical validity of this test and potential to substantially reduce the need for invasive diagnostic procedures and related pregnancy losses. 

This study follows and enhances previous attempts to validate the use of non-invasive prenatal testing for Down’s syndrome (see previous news). This is particularly relevant in the current context of sequencing costs falling at a high pace. With this validation study we move even closer to the potential use of this powerful technique in a clinical setting, which could also reduce the amount of necessary invasive diagnostic procedures carrying a non-negligible risk of miscarriage.