Enzyme: Dihydropteridine reductase (EC 1.5.1.34)

Reaction: q-Dihydrobiopterin > (NADH)> Tetrahydrobiopterin

DD: Mild (peripheral) to severe forms

Diagnosis: Blood, Urine, CSF, DNA
Blood: Phe (high), Neo (normal), Bio (high), DHPR activity (low)
Urine: Neo (normal), Bio (high)
CSF: Neo (normal), Bio (high), BH₂ (high), 5HIAA (low), HVA (low), 5MTHF (low)
DNA: see PNDDB

Clinical signs & symptoms:
Progressive dystonia
Truncal hypotonia
Hypertonia of extremities
Hypersalivation
Choreoathetoosis
Seizures
Mental retardation
Calcification of basal ganglia

Treatment:
L-Dopa/Carbidopa (10 or 25%) <15 mg/kg/d - 3-6 doses/day
5-OH-Trp <9 mg/kg/d - 3-6 doses/day
Folinic acid 10-20 mg/d - 2 doses/day
Low-Phe diet

Alternative treatment:
Deprenyl 0.1-0.3 mg/kg/d - 3-4 doses/day
Entacapone <30 mg/kg/d - 1-2 doses