Chromosomal abnormalities and copy number variations in fetuses with ventriculomegaly: a multicenter retrospective study

BACKGROUND: This study aimed to analyze chromosomal characteristics and copy number variations (CNVs) in fetuses with ventriculomegaly (VM), thereby comparing genetic features between the isolated VM group and the non-isolated VM. Simultaneously evaluate the efficacy of karyotyping and CNV analysis in prenatal diagnosis of fetuses with VM. METHODS: This retrospective cross-sectional study included 78 fetuses diagnosed with VM at the Prenatal Diagnosis Center, National Hospital of Obstetrics and Gynecology, the Clinical Genetics Center, Hanoi Medical University Hospital, and the Prenatal Diagnosis Center, Hanoi Obstetrics and Gynecology Hospital from January 2023 to December 2024. Genetic testing methods included conventional karyotyping and CNV analysis. RESULTS: Chromosomal abnormalities were detected in 14.1% (11/78) of cases by karyotyping, while CNVs were identified in 17.9% (14/78). CNVs were significantly more frequent in the non-isolated VM group compared to the isolated group (29.4% vs. 9.1%, p = 0.02). Both methods concordantly detected six cases of aneuploidy. Three cases of microdeletions/duplications were detected by CNV analysis, while karyotyping revealed no abnormalities. An additional four cases with chromosomal structural abnormalities detected by karyotyping had their deletion/duplication segments precisely characterized for size and location through CNV analysis. CONCLUSION: Genetic testing using amniotic fluid samples should be considered an essential component in the prenatal diagnostic approach to VM. Non-isolated VMs exhibit significantly higher CNV risk than isolated VMs. CNV analysis enhances diagnostic efficacy for genetic abnormalities compared to karyotyping, while simultaneously facilitating genetic variant classification, thereby providing more detailed information for prognostic assessment. The combined approach of karyotyping and CNV analysis improves the detection rate of genetic abnormalities, supporting enhanced genetic counseling and superior pregnancy management.