Metachromatic leukodystrophy: arylsulfatase-A deficiency in skin fibroblast cultures.

Fibroblasts cultured from the skin of a patient with metachromatic leukodystrophy have been found to manifest the biochemical defect of this inborn error of metabolism, a deficiency of arylsulfatase A. Diseased cells had less than five per cent of normal arylsulfatase-A activity, while activities of other lysosomal enzymes-including arylsulfatase B, beta-galactosidase, beta-glucuronidase, and beta-N-acetylglucosaminidase-were comparable to those in control cells. The presence of dissociable inhibitors in extracts of the diseased cells was excluded by combination experiments. The deficiency of the enzyme in leukocytes was also confirmed and is comparable to that found in cultured fibroblasts. The finding that readily cultured fibroblasts from easily obtained skin biopsy specimens exhibit the enzymatic defect should prove valuable in the biochemical study of this disease.