An autosomal dominant midline cleft syndrome resembling familial holoprosencephaly.

We have detected a previously unrecognized autosomal dominant syndrome characterized by: mental retardation, microcephaly; craniofacial anomalies including cleft lip and anterior cleft palate, hypotelorism and antimongoloid slant; skeletal anomalies, notably of the foot and spine; and chronic constipation. Despite similarities to familial holoprosencephaly, this disorder appears to be a distinct entity. Incomplete penetrance and variable expressivity accompany transmission of the abnormal allele through four generations of a large kindred. Three of the four affected males survived past 20 years of age; the fourth is an infant. All three affected females died very early in infancy.