Late Infantile Metachromatic Leukodystrophy: Arylsulfatase A and Saposin B Deficiency

Abstract

Metachromatic leukodystrophy is a genetic neurodegenerative disease with autosomal recessive transmission. It is characterized by an accumulation of sulfatides. We report a case of leukodystrophy related to a deficiency in saposin B. The diagnosis was suspected based on the initial clinical presentation, the progressive nature of the symptoms, involvement of both the central and peripheral nervous systems, and the typical radiological appearance on cerebral MRI. The normal arylsulfatase A levels led us to consider performing thin-layer chromatography of glycosphingolipids in urinary sediment to investigate a saposin B deficiency. The substantial excretion of sulfatides in our patient is virtually pathognomonic for metachromatic leukodystrophy due to saposin B activator deficiency. The diagnosis was definitively confirmed through molecular biology, which revealed the IVS+1 g>a mutation.