Prenatal genetic investigation in pregnancies with oligohydramnios: Results from a single referral medical center

Objective: The aim of this study was to investigate the value of genetic testing using exome sequencing (ES) in oligohydramnios pregnancies with or without other structural abnormalities. Materials and methods: A total of 110 singleton pregnancies complicated by oligohydramnios were enrolled, including 52 of isolated oligohydramnios and 58 of non-isolated oligohydramnios. All fetal samples were first tested by quantitative fluorescent polymerase chain reaction (QF-PCR) and followed by chromosomal microarray analysis (CMA). Those with normal CMA were informed of the option of trio ES. Results: QF-PCR detected chromosomal abnormality in 4 cases (4/110, 3.6%), including 1 of XXY, 1 of XYY and 2 of triploidy. The remaining 106 cases were tested by CMA, with pathogenic copy number variations (CNVs) detected in 5 cases (5/106, 4.7%), and uniparental disomy (UPD) in 2 cases (2/106, 1.9%). As an option for cases with a normal CMA, ES was accepted by 12 non-isolated cases, and pathogenic or likely pathogenic variants were detected in 5, involving the following genes: PBX1, FREM2, PKHD1 and BBS2, with a 41.7% (5/12) diagnostic rate. Conclusion: We provided further evidence of using advanced genetic approaches for oligohydramnios pregnancy. Non-isolated oligohydramnios increases the risk of having monogenetic conditions.