Autosomal dominant microcephaly.

Four families with autosomal dominant microcephaly are reported. Although the phenotype is nondistinctive, several patients had receding or small foreheads, upslanted palpebral fissures, or prominent ears. The degree of intellectual dysfunction is not as severe as that recorded in autosomal recessive microcephaly. It would appear that autosomal dominant microcephaly is more common than previously recorded, and that head circumference measurements of siblings and parents of affected patients should become a part of the initial investigation.