GM1-gangliosidosis is an autosomal recessive lysosomal storage disease characterized by accumulation of ganglioside substrates in lysosomes. Clinically, patients show variable degrees of neurodegeneration and skeletal abnormalities. There are 3 main clinical variants categorized by severity and variable residual beta-galactosidase activity. Type I, or infantile form (GM1G1), shows rapid psychomotor deterioration beginning within 6 months of birth, generalized central nervous system involvement, hepatosplenomegaly, facial dysmorphism, macular cherry-red spots, skeletal dysplasia, and early death. Type II, or late-infantile/juvenile form (GM1G2; 230600), has onset between 7 months and 3 years, shows generalized central nervous system involvement with psychomotor deterioration, seizures, localized skeletal involvement, and survival into childhood. Hepatosplenomegaly and cherry-red spots are usually not present. Type III, or adult/chronic form (GM1G3; 230650), shows onset from 3 to 30 years and is characterized by localized skeletal involvement and localized central nervous system involvement, such as dystonia or gait or speech disturbance. There is an inverse correlation between disease severity and residual enzyme activity.

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OMIM: GM1-gangliosidosis