Mucolipidosis IV (ML IV) is a rare inherited disease that causes slowly progressive nervous system deterioration. It is usually diagnosed during the first year of life.

Children with ML IV appear normal at birth but slowly develop nervous system problems. Motor skills, such as sitting, are delayed. Most children with ML IV do not learn to walk. Some children develop severe intellectual disabilities during the second or third year of life. Other symptoms of ML IV include clouding of the clear covering of the colored part of the eye (cornea), crossed eyes, and blindness. Most people with ML IV do not live beyond the age of 30.

There is no treatment for mucolipidosis IV. Support groups and counseling can be helpful for people with mucolipidosis IV and for their families. Genetic testing is recommended to identify carriers of the disease and to help guide decisions about having children.