Enzyme: Sepiapterin reductase (EC 1.1.1.153)

Reaction: 6-Pyruvoyl-tetrahydropterin > (NADP⁺) > Tetrahydrobiopterin

DD:

Diagnosis: CSF, Blood, FB, DNA
CSF: Sep (high), Bio (high), BH2 (high), 5HIAA (low), HVA (low)
Phe loading test (abnormal)
Blood: Prolactin (high)
FB: SR activty (low)
DNA: see PNDDB

Clinical signs & symptoms:
Motor and cognitive delay
Dystonia
Diurnal fluctuation
Oculogyric crises
Speech delay
Axial hypotonia
Limb hypertonia
Seizures

Treatment:
L-Dopa/Carbidopa (10 or 25%) <10 mg/kg/d - 3-4 doses/day
5-OH-Trp <9 mg/kg/d - 3-4 doses

Alternative treatment: