Cranial computerized tomography in dihydropteridine reductase deficiency.

Dihydropteridine reductase deficiency is a rare cause of hyperphenylalaninaemia, characterized by severe and progressive neurological impairment, despite early and accurate dietary control of plasma phenylalanine. We describe two girls, diagnosed at 17 and 14 months of age, respectively, and immediately treated with L-dopa, 5-hydroxytryptophan and carbidopa. In spite of an adequate dietary and pharmacological treatment, the clinical and neurological pictures progressively worsened. Repeated cranial computerized axial tomography scans showed degeneration of the white matter and, in one case, calcification of the basal ganglia. The possible association of this last finding with folate depletion is discussed.