A new mucolipidosis with psychomotor retardation, corneal clouding, and retinal degeneration

A 22 year old male had slow psychomotor development about 6 months after birth and developed intermittent corneal clouding at about 18 months. He developed truncal ataxia, hypotonia of the limbs combined with spasticity, and active deep reflexes. These have not progressed. His skeleton and facies are normal. Between his first and thirteenth year he developed severe optic atrophy, absence of retinal blood vessels, and an extinguished electroretinogram. Biochemical analysis of cultured fibroblasts indicated no lysosomal hydrolase deficiency; cellular metachromasia was absent and there was no mucopolysaccharidoses. Ultrastructural studies indicated single membrane vacuoles containing lamellated membranes and a polymorphous substance in tissue cultured cells and conjunctiva.