title: [Molecular basis for the heterogeneity of phenylketonuria].
abstract: The heterogeneity of phenylketonuria can be explained on the molecular basis. Because the phenylalanine-hydroxylating system consists of more than one enzyme, each enzyme can be mutated. Different mutations of the phenylalanine hydroxylase molecule resulting in a lack or reduction of enzyme activity can be anticipated. Enzyme activity lower than 1% compared to normals is correlated to the severe form; enzyme activity higher than 5% is correlated to the mild form of the disease. Phenylketonuria can also be caused by a defective synthesis or defective reduction of the cofactor. Patients suffer severe neurological symptoms, because of an impaired synthesis of dopamine and serotonin.
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D004298:Dopamine / Q000096:biosynthesis; D006801:Humans; D007223:Infant; D009422:Nervous System Diseases / Q000209:etiology / Q000378:metabolism; D010651:Phenylalanine Hydroxylase / Q000378:metabolism*; D010661:Phenylketonurias / Q000201:enzymology*; D012016:Reference Values; D012701:Serotonin / Q000096:biosynthesis
chemical_list: D012701:Serotonin; D010651:Phenylalanine Hydroxylase; D004298:Dopamine
vernacular_title: Die molekulare Basis der Heterogenität der phenylketonurie.