Inborn errors of metabolism: clues to understanding human behavioral disorders.

Detailed behavioral and biochemical investigation of patients with inborn errors of metabolism, especially those intrinsic to the nervous system, may provide many clues to the genetic predisposition underlying human behavioral traits. Relatives of such patients and other individuals with homologous enzymatic lesions due to alleles specifying intermediate activity need to be studied as well. Among the metabolic disorders discussed selectively here, some masquerade as schizophrenia, manic-depressive illness, or hyperactivity syndrome of childhood, providing examples of the striking heterogeneity to be found for these common behavioral disorders.