GTP cyclohydrolase 1 deficiency (Q105032)

GTP-cyclohydrolase I deficiency is an autosomal recessive inborn error of metabolism that causes of malignant hyperphenylalaninemia due to tetrahydrobiopterin deficiency, together with defective neurotransmission of monoamines. The principal manifestations include: psychomotor retardation, tonicity disorders, convulsions, drowsiness, irritability, abnormal movements, hyperthermia, hypersalivation, and difficulty swallowing.