Adams-Oliver syndrome revisited.

The occurrence of Adams-Oliver syndrome in a patient from the same geographic area as the first reported kindred led to follow-up of the original family, and to a survey of the literature. Of 81 cases in 32 families, there is an approximately equal distribution between sexes (38 males: 43 females). Vertical transmission in at least 8 families is consistent with autosomal dominant inheritance. The phenotype is variable with a range of mild-to-severe defects of the scalp and/or underlying bone. Despite large defects of the cranium, central nervous system abnormalities have not been found and intellectual development appears to be normal. Limb defects are usually limited to the digits, but may involve the long bones and are entirely absent in some obligate carriers of the gene. Cutis marmorata and tortuous, dilated scalp veins have been reported in association with the major head and limb defects, but also in isolation as a forme fruste phenotype. Thus, there is a broad range of variable expression ranging from cases with lethally hemorrhagic cranial defects and/or severe limb malformations, to patients without any apparent manifestations. Despite a phenotypic resemblance to isolated aplasia cutis congenita and to the syndrome of terminal transverse limb defects, Adams-Oliver syndrome appears to be causally distinct. While the underlying pathophysiologic mechanism remains unknown, it can be speculated that cranial vertex defects and malformations of the limbs represent field defects resulting from impaired circulation in "watershed" areas during a critical period of development.