GM-1 gangliosidosis
Type 1–infantile form, characterized by severe mental retardation and neurological, somatic, and osseous defects, accumulation of β-galactoside and death by age 2
Type 2–juvenile and adult form–milder than type 1, with death by age 10
GM-2 gangliosidosis
Type I Tay-Sachs disease, infantile amaurotic idiocy An AR–carrier frequency, Ashkenazi Jews,
1:25 condition due to hexosaminidase A deficiency, resulting in a 100-fold ↑ in GM-2 ganglioside in the brain Clinical Onset in early infancy with generalized hypotonia, apathy, and poor head control, 'cherry-red spots' in the optic macula
Type II Sandhoff's disease An AR condition caused by a complete deficiency of hexosaminidase A and B, with the CNS changes of Tay-Sachs disease, and visceral involvement; 100 to 200-fold ↑ in GM-2 gangliosides and a 50-100-fold ↑ in GA2, the asialo derivative of GM-2
in the brain, liver, spleen and kidney; type II is not more common in eastern European Jews
Type III Juvenile GM-2 gangliosidosis An AR condition , onset, age 2 to 6, with ataxia, psychomotor retardation, death by age 5-15; it is not associated with organomegaly and, like type I, more common in Ashkenazi Jews