ABSTRACT
Galactosialidosis is a lysosomal storage disease associated with a combined deficiency of beta-galactosidase and alpha-neuraminidase, secondary to a defect of another lysosomal protective protein. It is a neurodegenerative disorder clinically characterized by psychomotor deterioration, cerebellar ataxia, coarse facies, generalized bony deformity and organomegaly. Three phenotypic subtype are recognized:early infantile, late infantile and juvenile/adult type. We report a 13 months old boy with a late infantile galactosialidosis. He was presented with progressive mental regression and motor disturbance and observed cherry red spot, hearing loss, moderate dysostosis multiplex and vacuolated lymphocytes in peripheral blood. He showed only beta-galactosidase deficiency in the lymphocytes and was diagnosed as GM1-gangliosidosis type 1. However, further studies revealed the possible defect of alpha-neuraminidase suggesting that he was a case of galactosialidosis which was mimicking GM1-gangliosidosis type 1.