Two Atypical Cases of Adams–Oliver Syndrome With <scp> <i>DOCK6</i> </scp> Genetic Variants

Adams-Oliver syndrome (AOS) is characterized by scalp aplasia cutis congenita (ACC) and terminal transverse limb defects (TTLD). Autosomal recessive AOS type 2 caused by DOCK6 variants is usually accompanied by central-nervous-system and ocular anomalies. We report two unrelated children who each carried compound heterozygous DOCK6 variants. Both presented with variable degrees of global developmental delay and visual impairment, but neither showed ACC or TTLD. Our observations highlight the phenotypic variability in DOCK6-related AOS and a possible ascertainment bias in screening patients only with typical AOS phenotypes. Genome sequencing and related genetic testing techniques are advised.