Sanfilippo B disease: a re-examination of a particular sibship after 12 years.

A particular sibship, with mild and severe types of Sanfilippo B disease within the same family, was re-examined after 12 years. The phenotypes of the mild and of the severe patients were maintained, specifically the mental retardation. Cultures of lymphoblasts from the mild patient were established and proteins were electrophoresed in native conditions and then immunoblotted with specific antibody. Two bands of 182,000 and 131,000 Da were found, comigrating with the enzyme from normal lymphoblasts and the enzyme from normal urine. The data are discussed in relationship to the molecular defect underlying alpha-N-acetylglucosaminidase deficiency and to the ability of the antiserum to react with normal, mutant, monomeric and multimeric forms of the enzyme.