Prenatal diagnosis of fetal chromosomal abnormalities among 2318 pregnant women with indications in southern China: a retrospective study

Abstract Background To investigate the frequency of fetal chromosomal abnormalities among women with abnormal ultrasound, abnormal biochemical marker screening or noninvasive prenatal testing results, advanced maternal age, or history of miscarriage in southern China. Methods We retrospectively analyzed prenatal samples from pregnant women between 2015 and 2019. Conventional karyotyping was performed using GTG banding. Copy number variation sequencing was used when indicated to identify chromosomal abnormalities. Results A total of 2,318 prenatal samples (188 chorionic villus samples, 2,003 amniotic fluids, and 127 cord blood) were analyzed. The frequency of chromosomal abnormalities was 12.4% (288/2,318) in prenatal samples, and frequency in chorionic villus samples (23.9%) was higher than in amniotic fluids (13.5%) and in cord blood (5.0%; P < 0.001). Numerical anomalies were detected in 195 (8.4%) cases and the most common abnormality were trisomy 21 (103/2,318; 4.4%), trisomy 18 (31/2,318; 1.3%) and monosomy X (18/2,318; 0.8%). Sructural anomalies were found in 29 (1.3%) cases, rare anomalies such as deletions (4 cases), duplications (2 cases), and complex rearrangement (1 case), were detected. Two cases with common chromosomal polymorphisms, inv(9)(p11q12) and inv(9)(p11q13), associated with recurrent spontaneous abortion, were detected. Five fetuses had normal karyotypes and definite pathogenic copy number variations, with microdeletions at 16p13.11, 16p12.1 (2 cases), and 17p12 and a microduplication at 7q11.23; all had normal phenotypes after birth. Conclusion Our study indicated that fetal chromosomal anomalies can be detected in early gestation and provided valuable information for interpretation of chromosomal polymorphisms and copy number variations.