Metachromatic leukodystrophy. Ultrastructural and enzymatic study of a case of variant O form.

A variant of metachromatic leukodystrophy (MLD), Austin disease, is characterized by a multiple isozyme deficiency of arylsulfatase. A 3 1/2-year-old girl with progressive mental and physical deterioration had decreased activities of arylsulfatases A and B in the leukocytes, shown by acylamide gel electrophoresis. Under the electron microscope, biopsy specimens of the brain and the peripheral nerve showed lamellar structures with socalled zebra bodies in the cytoplasmic processes of glial cells, granulo-membranous inclusions with fingerprint configurations in neurons, and myelinlike material in Schwann cells. Results from our study suggest an intricate nature of this dysmetabolic disorder, which shows ultrastructural changes usually seen in classic MLD, a deficiency of arylsulfatase A only, concomitant with those seen in mucopolysaccharidoses such as Hurler and Sanfilippo syndromes.