GM1 gangliosidosis (MONDO_0018149) is a rare lysosomal storage disorder characterized biochemically by deficient beta-galactosidase activity and clinically by a wide range of variable neurovisceral, ophthalmological and dysmorphic features. Also known as: Beta-galactosidase deficiency, Beta-galactosidase-1 deficiency, GLB1 deficiency, GM>1< gangliosidosis, Landing disease, Landing syndrome, beta-galactosidase deficiency, deficiency of beta-galactosidase.