Mucolipidosis type IV (MLIV) is an autosomal recessive disorder typically characterized by severe psychomotor delay evident by the end of the first year of life and slowly progressive visual impairment during the first decade as a result of a combination of corneal clouding and retinal degeneration. The purpose of this research study is to look at the brain and eye in patients with mucolipidosis type IV (MLIV). MLIV is a lysosomal storage disease that primarily affects the brain and the eyes. The disease is caused by a defect in a gene called MCLON1 that makes a protein called mucolipin-1. Patients with MLIV do not make enough normal mucolipin. The disease begins early in life and the neurological problems seem to stabilize later in life. On the other hand, the eye abnormalities usually progresses over time. The exact course of the disease has not been determined, and until now, no study has addressed this question carefully. The research objectives are: <ol> <li>To learn about the natural history of cognitive function for individuals with mucolipidosis type IV.</li> <li>To measure brain volume over time in individuals with mucolipidosis type IV</li> </ol> This is an observational study of individuals with MLIV disorder. Those participating in this study will be evaluated annually for five years following a baseline visit.

The Natural History of Mucolipidosis Type IV

Quantitative neuroimaging in mucolipidosis type IV.