Adams-Oliver syndrome

Adams-Oliver syndrome, abbreviated AOS, is a rare congenital disorder defined by two key features: aplasia cutis congenita, meaning missing skin, usually at the top of the skull and sometimes with a defect in the underlying bone, and terminal transverse defects of the limbs such as shortened digits. The skin often has a mottled look, and some people have mild growth deficiency, heart and blood vessel malformations, cleft lip or palate, kidney abnormalities, seizures or developmental delay. Inheritance was first described as autosomal dominant, with varying severity within families, though some cases are autosomal recessive. Six genes have been identified: ARHGAP31, DOCK6, RBPJ, EOGT, NOTCH1 and DLL4. The first two regulate Rho family GTPases that shape the cell skeleton, and the other four act in the Notch signalling pathway.