(HealthDay News) – A novel biochemical assay (Digital Analysis of Selected Regions [DANSR]) combined with an algorithm (Fetal-fraction Optimized Risk of Trisomy Evaluation [FORTE]) accurately identifies the risk of fetal trisomy 21 and 18 from maternal-blood cell-free DNA (cfDNA), according to two studies published online Jan. 27 in the American Journal of Obstetrics & Gynecology.
Andrew B. Sparks, PhD, from Aria Diagnostics in San Jose, CA, and colleagues tested DANSR and FORTE using cfDNA obtained from maternal blood in a training set (163 subjects) and a blinded validation set (167 subjects). An individualized trisomy risk score was produced for each subject using FORTE, which correctly discriminated all cases of trisomy 21 and 18 from disomic cases. All subjects in the validation set passed quality control, and FORTE performance discriminated 36 of 36 cases of trisomy 21 and eight of eight cases of trisomy 18 from 123 of 123 disomic cases.
Ghalia Ashoor, MD, from the University of London, and colleagues used the DANSR assay and the FORTE algorithm to assess the prenatal detection of trisomies 21 and 18 using maternal-plasma cfDNA obtained at 11–13 weeks of gestation. Risk scores for trisomy 21 and 18 were given for 397 samples. The sensitivity for detecting trisomy 21 and 18 was 100% and 98%, respectively, and the specificity was 100%.
“This nested case-control study has demonstrated that the DANSR assay with FORTE algorithm represent a promising method for accurate detection of fetal trisomy 21 and trisomy 18,” Ashoor and colleagues write.
All authors of the Sparks study are paid employees of Aria Diagnostics.