Studies of a family with incontinentia pigmenti variably expressed in both sexes.

A family is described in which incontinentia pigmenti (IP) is variably expressed in both sexes, compatible with either autosomal dominant or X linked dominant inheritance. This is the first reported instance of an affected male with a positive family history. Immunological studies of the proband showed no significant alteration of immune function. Cytogenetic investigations of the proband and her affected brother and mother revealed no unusual propensity for chromosome breaks or gaps and no enhancement of sister chromatid exchanges.