Hyperphenylalaninemia, BH4-deficient, D

An autosomal recessive disease characterized by primapterinuria, a variant form of hyperphenylalaninemia defined by increased excretion of 7-substituted pterins in the urine. Patients with primapterinuria show an increased ratio of neopterin to biopterin in the urine, excretion of subnormal levels of biopterins, and normal levels of biogenic amines in cerebrospinal fluid. Neurologic signs are mild, present in the neonatal period only, and include hypotonia, delayed motor development and tremor.