title: New variant of phenylketonuria with progressive neurological illness unresponsive to phenylalanine restriction.
abstract: Three children, two of them siblings, with an unusual type of phenylketonuria are described.  The three patients, two of them observed from the neonatal period, had a progressive neurological illness which was unlike that of classical phenylketonuria, and which did not respond to a low phenylalanine diet.  The biochemical features suggested that the block in the conversion of phenylalanine to tyrosine was less severe than in the classical disease, and phenylalanine rho-hydroxylase activity, measured in one patient was normal.  It is suggested that the patients have a disorder of biopterin metabolism possibly due to a defect of the enzyme dihydropteridine reductase.
mesh_terms: D001708:Biopterins / Q000378:metabolism; D002648:Child; D002675:Child, Preschool; D003680:Deglutition Disorders / Q000209:etiology; D004093:Dihydropteridine Reductase / Q000378:metabolism; D005260:Female; D006801:Humans; D007223:Infant; D008607:Intellectual Disability / Q000209:etiology; D008297:Male; D009468:Neuromuscular Diseases / Q000209:etiology*; D010649:Phenylalanine / Q000008:administration & dosage / Q000097:blood / Q000378:metabolism; D010661:Phenylketonurias / Q000150:complications* / Q000178:diet therapy / Q000378:metabolism; D012640:Seizures / Q000209:etiology*; D014443:Tyrosine / Q000097:blood
chemical_list: D001708:Biopterins; D014443:Tyrosine; D010649:Phenylalanine; D004093:Dihydropteridine Reductase