Clinical and molecular heterogeneity in hereditary beta-galactosidase deficiency.

Results of a molecular analysis of GM1-gangliosidosis and galactosialidosis in our laboratory are briefly reviewed. A common single base substitution was found in adult/chronic form of GM1-gangliosidosis among heterogeneous beta-galactosidase gene mutations, and restriction site analysis was successfully performed for diagnosis of homozygotes and heterozygotes. All adult galactosialidosis patients had a common mutation at a splice junction which caused skipping of an exon of the protective protein/carboxypeptidase gene. An artificial restriction site was introduced in this case and applied to diagnosis of this disease. The heterogeneous gene mutations were compared and correlated with phenotypic manifestations in these two diseases.