also referred to as mucolipidosis
III (ML III), is lysosomal storage disease
closely related to I-cell disease
(ML II). Symptoms of ML III are often not noticed until the child is 3-5 years of age.
As in ML II, ML III results from genetic defects in GlcNAc phosphotransferase (N-acetylglucosamine-1-phosphotransferase
). However, ML III produces less severe symptoms and progresses more slowly, probably because the defect in GlcNAc phosphotranspherase lies in its protein recognition domain. Therefore, the catalytic domain retains some of its activity, resulting in a smaller accumulation of carbohydrates, lipids, and proteins in the inclusion bodies.
Patients with ML III are generally of normal intelligence
(trait) or have only mild mental retardation
. These patients usually have skeletal abnormalities, coarse facial features, short height, and corneal clouding. Some individuals with ML III survive until their fourth or fifth decade of life.
- - original text of article derived from detail sheet available here