Clinical and molecular characteristics of 11 Chinese probands with GM1 gangliosidosis

GM1 gangliosidosis is an autosomal recessive lysosomal storage disease caused by the deficiency of beta-galactosidase activity, precisely due to mutations in the GLB1 gene. To explore the clinical and molecular characteristics of GM1 gangliosidosis patients from China, GLB1 gene were analyzed in 11 probands with GM1 gangliosidosis by exploiting direct Sanger-sequencing. Among them, five patients were classified as the infantile type and the remaining six as the late-infantile or juvenile type. In these probands, eight novel mutations p.Y50N, p.Y237C, p.S267F, p.G453R, p.K578N, c.618delC, c.475_478delGACA and c.1979_1980insG have been identified. Among them, three novel missense mutations p.Y50N, p.S267F and p.G453R were transiently transfected in COS-7 cells by plasmid system for functional verification. In vitro GLB1 activities carrying the aforesaid missense mutants p.Y50N, p.S267F and p.G453R were 0.11%, 0 and 0.55% of wild-type, respectively. Mutation c.495_497delTCT and p.S149F accounted for 22.7 and 13.6% of the mutant alleles, respectively. Our results expand the spectrum of GLB1 gene, provide new insights into the clinical and molecular characteristics of GM1 gangliosidosis in China.