Maladaptive behavior in children with Prader-Willi syndrome, Down syndrome, and nonspecific mental retardation.

Although some genetic, mental retardation syndromes have well-described behavioral features, comparative studies have not yet assessed the relative uniqueness of these so-called phenotypes. Maladaptive behavior of 43 children with Prader-Willi syndrome was compared to age- and gender-matched children with Down syndrome and with nonspecific mental retardation. The Prader-Willi group showed more frequent and severe internalizing, externalizing, and total problem behaviors on the Child Behavior Checklist. Some problems were elevated in all groups, and 12 behaviors were significantly elevated in Prader-Willi subjects relative to both comparison groups. Seven behaviors predicted membership into the Prader-Willi group with 91% accuracy. Implications were discussed for research on behavioral phenotypes in general and for dual diagnosis in particular.