Best Practice & Research clinical obstetrics & gynaecology

Screening for fetal genetic disorders is a focus of prenatal care. Cell free DNA (cfDNA) screening for aneuploidies became available in 2011. Initially available only to high-risk individuals, this test is now standard of care in many settings. cfDNA screening has expanded to include sex chromosomal aneuploidies, copy number variants, and rare autosomal trisomies. However, the positive predictive value for rarer conditions is significantly lower, the number of conditions tested for is small, and abnormal results may occur due to maternal genetic findings. The field is changing quickly, and national recommendations for the use of cfDNA in screening for fetal and maternal diseases varies internationally. Research on the performance of screening for many different genetic disorders using cfDNA is ongoing, and suggests that this methodology may allow for testing of a much greater number of genetic conditions. Additionally, improved understanding of the cfDNA molecules themselves may provide additional insights: both high and low fetal fractions may suggest adverse pregnancy outcomes, and characteristics of the fragments themselves may help distinguish tissue of origin.