Personality characteristics of nonretarded phenylketonurics and their family members.

The effect of phenylketonuria cannot be restricted merely to the intellectual function of the central nervous system. Because of increasing evidence that phenylketonurics present different personality problems, this study was undertaken to learn the personality characteristics of 19 nonretarded phenylketonurics, their 27 unaffected siblings, and 36 parents as reflected in their MMPI profiles. Results indicated increased incidence of psychopathology in male PKUs, and, to a lesser extent, unaffected male siblings. No consistent trend toward psychopathology was found in female PKUs, female siblings or in parents. Personality profiles indicating significant psychopathology were more frequently encountered among adult male PKUs than among adolescent male PKUs. This study suggests that heterozygous parents of phenylketonurics do not manifest psychopathological personality characteristics, and that male offspring of heterozygous mothers have a higher risk of developing psychopathology than have female children.