True Fetal Trisomy 22 Detected Using Genome-Wide Noninvasive Prenatal Testing

Excerpt

Autosomal aneuploidies occurring in chromosomes other than 13, 18, and 21 and sex chromosomal aneuploidies are referred to as 'Rare autosomal aneuploidies' (RAAs). A prenatal incidence of 0.41% is noted for RAAs on chorionic villus sampling (CVS) procedures. Aneuploidies in autosomes other than 13, 18, and 21 and sex chromosomal aneuploidies may result in increased fetal-placental diseases such as non-viable pregnancy, early miscarriage, intrauterine fetal growth restriction, uniparental disomy, multiple congenital anomalies, fetal demise, or normal live birth [1]. The screen-positive rate of RAAs on NIPT is 0.04% to 0.83%. However, the PPV of RAAs on NIPT is found to be 6–29%. The increased false positives for RAAs on NIPT are most commonly due to confined placental mosaicism (CPM) [2] but may also arise due to vanishing twin or maternal malignancies. Clinically relevant abnormalities can be detected in 30–75% of the high-risk cases of RAAs in NIPT [1]. …