Attitudes and psychosocial adjustment of unaffected siblings of patients with phenylketonuria

Sibling illness may contribute to an increased risk of adjustment problems in healthy siblings. Previous studies have reported a variety of effects on healthy individuals who have an ill sibling, but the psychosocial effects of treatable inherited disease on healthy siblings have not yet been investigated. We report the results of a survey study conducted in families with both unaffected and affected children with classic phenylketonuria (PKU), an inherited inborn error of metabolism. The survey included a knowledge test about PKU, and four previously validated instruments designed to assess psychosocial adjustment of unaffected siblings compared to age and sex matched norms. The responses revealed that unaffected adolescent and adult siblings had gaps in their knowledge about the genetic basis of PKU, and had evidence for the presence of adverse psychosocial sequelae. These findings suggest a role for genetic services providers, including genetic counselors, in assisting all members of a family adjust, when the diagnosis of an inborn error of metabolism has been made.