GLB1 and GM1 gangliosidosis type 1: Homozygous or compound heterozygous mutations of the gene encoding for beta-galactosidase-1 (GLB1) on chromosome 3p22.3 can originate two clinically distinct, albeit allelic, disorders: GM1-gangliosidosis type 1 and mucopolysacharidosis type IVB, also known by the eponym Morquio syndrome type B.