Saposin B deficiency as a cause of adult-onset metachromatic leukodystrophy

Metachromatic leukodystrophy (MLD; OMIM #250100) is a panethnic, autosomal recessive disease characterized by intralysosomal accumulation of sulfatides, mainly in oligodendrocytes and Schwann cells. MLD classically presents in childhood, and results from mutations in ARSA gene,1 encoding arylsulfatase A (ARSA), a lysosomal enzyme responsible for sulfatide degradation.