Phenotypic findings and pregnancy outcomes of fetal rare autosomal aneuploidies detected using chromosomal microarray analysis

BACKGROUND: Aneuploidies are the most common chromosomal abnormality and the main genetic cause of adverse pregnancy outcomes. Since numerous studies have focused on common trisomies, relatively little is known about the association between phenotypic findings and rare autosomal aneuploidies (RAAs). We conducted a retrospective study of 48,904 cases for chromosomal microarray analysis in a large tertiary referral center and reported the overall frequencies, clinical manifestations, and outcomes of prenatal RAAs. RESULTS: A total of 90 RAAs were detected, of which 83 cases were mosaic trisomies and 7 were non-mosaic trisomies. Chromosomes 16, 22, and 9 were identified as the major chromosomes involving RAAs. The four predominant indications for prenatal diagnosis in our RAA cases were RAA-positive in noninvasive prenatal screening, advanced maternal age, ultrasound abnormalities, and high-risk for serum prenatal screening. Cardiovascular defects were the most frequently observed structural abnormalities, followed by musculoskeletal anomalies. Increased nuchal translucency and persistent left superior vena cava, the major soft marker abnormalities involved, were also observed in our RAA cases. Clinical outcomes were available for all RAAs, with 63 induced abortions and 27 live births recorded. CONCLUSIONS: Variable phenotypes and outcomes were observed, which were highly heterogeneous in cases of prenatal RAAs. Thus, a cautious and comprehensive strategy should be implemented during prenatal counseling for RAAs. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s40246-022-00438-4.