A Novel Homozygous GLB1 Pathogenic Variant Identified in Two Cases of Infantile GM1 Gangliosidosis

GM1 gangliosidosis is a rare genetic disorder that affects lysosomes. It is caused by variants in the GLB1 gene, which leads to a lack of the enzyme β-galactosidase. The infantile form (Type I) is the most severe. It begins in the first months of life and has a poor prognosis. We report two cases of infantile GM1 gangliosidosis from two consanguineous families.Patient I, evaluated at 9 months, showed developmental delays that began at 3 months, along with distinct physical features and significantly reduced levels of β-galactosidase enzyme activity. Patient II, also evaluated at 4 months, presented with severe neurological symptoms, cherry-red spots, and hepatosplenomegaly. This patient also harbored a novel homozygous variant c.169T > C, p.(Tyr57His) in the GLB1 gene not previously reported. These cases show the range of symptoms in infantile GM1 gangliosidosis and provide new genetic information by identifying a novel pathogenic variant. Early diagnosis through enzyme testing and genetic analysis is vital for advising families and developing prevention strategies in high-risk groups.