Novel compound heterozygous DOCK6 variants expand the mutational spectrum in prenatal diagnosis of Adams-Oliver syndrome 2.

Background: Adams-Oliver syndrome (AOS) is a rare developmental disorder, and the DOCK6 gene is an identified AOS gene. This report highlights the prenatal diagnosis of AOS-2 by ultrasonography and genetic testing.

Methods: A growth-restricted fetus with bilateral ventriculomegaly, paraventricular calcifications, and ventricular septal defect underwent trio-whole-exome sequencing (trio-WES). Functional validation of the splice-altering variant was performed via minigene assays and protein structural modeling.

Results: Trio-WES revealed compound heterozygous DOCK6 variants: a paternal frameshift (c.3190_3191del; p. Leu1064Valfs60) and a maternal splice-site variant (c.3241-1G > T). Minigene assays demonstrated that c.3241-1G > T caused intron 26 retention (486 bp), introducing a premature termination codon (p. Val1081Glufs37). Structural modeling confirmed the loss of critical DHR2 domains in both truncated proteins.

Conclusions: This study expands the mutational spectrum of DOCK6 and underscores the importance of combining prenatal imaging with functional genomics for early diagnosis of AOS2.