Gene: GCH1

Enzyme: GTP cyclohydrolase I (EC 3.5.4.16)

Reaction: GTP >> Dihydroneopterin triphosphate + Formiate

DD: arGTPCH deficiency (hyper-Phe)

Diagnosis: CSF, FB, DNA
CSF: Neo (low), Bio (low), 5HIAA (normal), HVA (low)
Phe Loading test (abnormal)
FB: GTPCH activty (low)
DNA: see PNDDB

Clinical signs & symptoms:
Dystonia of lower limbs, trunk, arms, neck
Diurnal fluctuations of symptoms
Parkinsonism (adulthood)

Treatment:
L-Dopa/Carbidopa (10 or 25%) <12 mg/kg/d - 3-4 doses/day

Alternative treatment:

Literature:
Diagnosis
Treatment