GM1 gangliosidosis is a lysosomal disorder caused by β-galactosidase deficiency due to mutations in the GLB1 gene. It is a rare neurodegenerative disorder with an incidence of about 1:100,000-1:200,000 live births worldwide. Here we review GLB1 mutations and clinical features from 65 Brazilian GM1 gangliosidosis patients. Molecular analysis showed 17 different mutations and c.1622-1627insG was the most frequent, accounting for 50% of the alleles. Cognitive impairment was the main clinical sign, observed in 82% of patients, followed by hepatosplenomegaly observed in 56% of patients. It was possible to establish a significant correlation between age at onset of symptoms preceding the first year of life and the presence of the mutation c.1622-1627insG (p=0.03). Overall our findings differ from literature and represent the exclusive genotypic profile found in Brazilian GM1 gangliosidosis patients.