A variant form of metachromatic leukodystrophy without arylsulfatase deficiency

The clinical, pathological, and biochemical findings in a young woman with a new variant of metachromatic leukodystrophy (MLD) are reported. The patient showed slow early development and deteriorated further during her first two decades. Nerve conductions were slow, and a sural nerve biopsy showed features of a sulfatide lipidosis. Urinary sulfatide excretion was comparable to that of patients with classic MLD, yet in vitro activity of arylsulfatase A and B and cerebroside sulfatase activity were normal. Skin fibroblasts cultured in medium supplemented with 3H-labeled sulfatide showed accumulation of labeled sulfatide in large amounts, implying a defect in sulfatide hydrolysis in vivo in spite of intact enzyme activity in vitro.