GM_2神经节苷脂病的共同基础缺陷是常染色体隐性遗传的溶酶体氨基己糖苷酶缺乏而致GM_2神经节苷脂在神经元中沉积。氨基己糖苷酶系统有由α-和β-亚单位不同组合而形成的两种主要同功酶-氨基己糖苷酶A和B。此外,酶的活性还依赖一种激活蛋白。三种遗传上不同位点的突变均可影响GM_2的代谢。典型的Tay-Sachs氏病和Sandhoff氏病表现为婴儿的进行性智力及运动功能衰退、惊吓反射增强、抽搐及黄斑部樱桃红点脑病表现,其他已知的临床综合征包括晚期婴儿或少年期的脑病、小脑性共济失调、非典型的脊髓小脑共济失调、kugelberg Welander表型的慢性脊肌萎缩、类肌萎缩侧索 The common underlying defect in GM_2 ganglioside disease is the absence of autosomal recessive lysosomal hexosaminidase that causes deposition of GM_2 gangliosides in neurons. The hexosaminidase system has two major isozymes, hexosaminidases A and B, formed by different combinations of α- and β-subunits. In addition, the enzyme activity also depends on an activating protein. Mutations in three genetically different loci all affect GM2 metabolism. Typical Tay-Sachs and Sandhoff’s disease manifest as progressive intellectual and motor impairment in infants, increased scared reflexes, convulsions and macular degeneration of cherry-red encephalopathy. Other known clinical syndromes include late infancy or adolescence Encephalopathy, cerebellar ataxia, atypical spinocerebellar ataxia, chronic atrophy of the kugelberg Welander phenotype, amyotrophic lateral sclerosis