Cell-free DNA analysis for trisomy risk assessment in first-trimester twin pregnancies

Fetal Diagn Ther. 2014;35(3):204-11. doi: 10.1159/000356495. Epub 2013 Nov 15.


Objective: To examine the clinical implementation of chromosome-selective sequencing of cell-free DNA (cfDNA) in maternal blood and an algorithm that relies on the lower fetal fraction contribution of the 2 fetuses in the assessment of risk for trisomies in twin pregnancies.

Methods: Risk for trisomies 21, 18 and 13 by cfDNA testing were estimated in stored plasma samples obtained at 11-13 weeks' gestation from 207 pregnancies with known outcome and prospectively in 68 twin pregnancies undergoing screening at 10-13 weeks.

Results: Risk scores for trisomies were provided for 192 (92.8%) of stored plasma and for 63 (92.6%) of the prospective cases. In the retrospective study, 10 of 11 trisomic pregnancies were correctly identified with no false positive results. In the prospective study, 3 trisomic pregnancies were correctly identified with no false positive results. The median of the lower fetal fraction in the prospective study of twins was 7.4% (IQR range 5.9-10.0%), which was lower than in our previous study in singletons (median 10.0%, IQR 7.8-13.0%).

Conclusions: cfDNA testing in twins is feasible but the reporting rate of results is lower than in singletons due to a lower fetal fraction.

Publication types

  • Research Support, Non-U.S. Gov't
  • Twin Study

MeSH terms

  • Adult
  • Cell-Free System / physiology
  • DNA / genetics*
  • Female
  • Humans
  • Maternal Serum Screening Tests / methods*
  • Middle Aged
  • Pregnancy
  • Pregnancy Trimester, First / genetics*
  • Pregnancy, Twin / genetics*
  • Prenatal Diagnosis / methods
  • Prospective Studies
  • Retrospective Studies
  • Risk Assessment
  • Trisomy / genetics*


  • DNA