The symptoms of Mucolipidosis Type IV (ML IV) occur when the chemical that typically breaks down certain fatty substances (lipids) in the body is not present.  These lipids then accumulate to toxic levels throughout the body. 

Children with ML IV appear normal at birth, but by about one year of age, they begin to show signs of motor and mental delays. ML IV also causes eye problems, including clouding of the corneas, strabismus (crossed eyes), and degeneration of the retina, which may lead to blindness. 

No treatment is currently available for ML IV; supportive care is used to treat various symptoms. 

Although ML-IV can occur in any ethnicity, it is more common in individuals of Ashkenazi Jewish descent. Approximately 1 in 125 Ashkenazi Jews is a carrier of ML IV.