G M1 Gangliosidosis: Phenotypic variation in a single family

Infantile, juvenile, and adult forms of G M1 gangliosidosis have been well characterized. Certain genetic and biochemical studies have suggested that the phenotypic variation found in G M1 gangliosidosis results from different allelic mutations affecting the G M1 ganglioside β‐galactosidase locus and that different combinations of these mutations account for the clinical heterogeneity of this illness. A family in which both the infantile and juvenile forms of G M1 gangliosidosis occurred, the children sharing a common mutation of their acid β‐galactosidase activity, supports the allelic nature of these different clinical forms of the disease. From the observations made in this unique family, additional phenotypes of G M1 gangliosidosis might be anticipated.