Reversible white matter lesion in methionine adenosyltransferase I/III deficiency.

A 5-year-old boy with methionine adenosyltransferase (MAT) I/III deficiency, under treatment for the tentative diagnosis of homocystinuria, presented with mildly decreased appetite and sleepiness. MR imaging showed abnormal T1 and T2 prolongations and reduced diffusion in the cerebral white matter. Clinical symptoms and MR imaging findings improved after discontinuation of therapy. We speculate that inappropriate treatment might enhance CNS lesions of MAT I/III deficiency by causing a reversible vacuolating myelinopathy.