ALPHA-N-ACETYLGALACTOSAMINIDASE DEFICIENCY WITH MILD CLINICAL MANIFESTATIONS AND DIFFICULT BIOCHEMICAL-DIAGNOSIS

Two additional patients with alpha-N-acetylgalactosaminidase (alpha-NA GA) deficiency are described. An ii-month-old girl with nonconsanguine ous parents had generalized seizures and no angiokeratoma. Biochemical investigation showed persistent slight oligosacchariduria; enzymatic analysis of plasma, leukocytes, and fibroblasts revealed profound alph a-NAGA deficiency. Heterozygote enzyme levels were found in both paren ts. The mother has epilepsy, and epilepsy is present in the father's f amily. A younger, clinically healthy brother also had the enzyme defic iency. Electron microscopy Of lymphocytes from the index patient showe d no vacuolization. Incubation of cultured fibroblasts with Helix poma tia lectin showed the presence of intracellular N-acetylgalactosamine- containing storage material, not present in a series of 12 normal fibr oblast lines. Our cases cannot be classified definitely as infantile c ases. Biochemically the diagnosis could easily have been missed. Urina ry oligosaccharide pat tern of ter resorcinol staining was identical t o those previously described, but excretion was significantly lower th an in the reported infantile cases and the bends disappeared after the urine was desalted. The enzyme defect in leukocytes would have been m issed with one of the commercial substrates used. For this mild varian t of alpha-NAGA deficiency, the clinical pattern is not yet clear; a l onger follow-up period is needed.