We report a 16-year-old man with disorders of tetrahydrobiopterin metabolism due to dihydropteridine reductase (DHPR) deficiency. He revealed moderate mental retardation, parkinsonism, and spastic paralysis with levodopa and 5-hydroxytryptophan (5-HTP) supplementation from the age of 2 months. Brain MRI showed high intensity areas in bilateral frontal and posterior deep white matter on fluid-attenuated inversion recovery (FLAIR). Coronal FLAIR image showed a high signal in bilateral pyramidal tracts. Single photon computed tomography (SPECT) imaging of the dopamine transporter was normal. This imaging indicates no dopaminergic cell loss. Our patient had no motor fluctuations or dyskinesias. Early diagnosis and replacement treatment might lead to a favorable outcome.
Keywords: Dihydropteridine reductase deficiency; Dopamine transporter; Hyperphenylalaninemia; Levodopa; Parkinsonism; SPECT.