A lysosomal storage disease with clinical characteristics of psychomotor retardation and visual abnormalities including corneal clouding, retinal degeneration or strabismus. The disease is rare in the general population but is more prevalent among Ashkenazi Jews. First signs appear during the first year of life or later, but clinical progression is usually slow. In this disease phospholipids, gangliosides and mucopolysaccharides accumulate in lysosomal inclusions, some of which resemble membranous cytoplasmic bodies found in gangliosidoses. The condition seems to be caused by anomalies in the endocytosis of membrane components towards the lysosomes. The causative gene, MCOLN1, is located in the 19p13.3-p13.2 region and encodes mucolipin-1 (MLN1), a membrane protein from the transient receptor potential (TRP) channel family. The disease is transmitted as an autosomal recessive trait.