Myoclonic epilepsy of Lafora and arylsulphatase A deficiency in the same patient.

Very low levels of arylsulphatase A were found in a young patient with the clinical features of Lafora disease, confirmed by muscle biopsy. The deficiency was shown both in leukocytes and cultured fibroblasts. A cerebroside sulphate loading showed that 93% of [14C]cerebroside sulphate taken up by skin fibroblasts from the patient remained unmetabolized after a 24h pulse, ruling out pseudo-arylsulphatase A deficiency. In the healthy parents and siblings of the patient, biochemical data suggested heterozygosity for arylsulphatase A deficiency. The apparent co-inheritance of arylsulphatase A deficiency and Lafora disease in this family might be the consequence of genetic linkage between the two genes.