Chicago Center for Jewish Genetics Disorders - Ashkenazi Disorders: Mucolipidosis IV

Ashkenazi Disorders: Mendelian

Gene: Mucolipidosis IV is caused by a defect in the MCOLN1 gene, which is located at 19p13.2-13.3. This gene encodes for mucolipin-1 protein, which is hypothesized to play a role in endocytosis of lipids into lysosomes.

Mutations and testing: More than 80% of patients with mucolipidosis IV are Ashkenazi Jews. Two mutations account for greater than 95% of mutant alleles seen in Ashkenazi Jews. These are IVS3 1A->G del (EX1-EX7). Additional testing can be done to test for achlorhydria associated with elevation of serum gastrin levels. Characteristic storage bodies are seen in skin fibroblasts.

Traits: Mucolipidosis IV (MLIV) is a neurodegenerative lysosomal disorder with a clinical phenotype ranging from severe to mild ophthalmologic and/or neurologic signs. Ophthalmologic signs consist of corneal clouding from birth or in early childhood, retinal degeneration, visual impairment due to optic atrophy and retinopathy, myopia, convergent strabismus, and photophobia. Neurologic signs include psychomotor delay, hypotonia, and developmental delay. Most patients reach a maximal developmental level of 12 to15 months and then plateau. MLIV is often misdiagnosed as cerebral palsy. Long-term outcome and life expectancy are unknown. Affected individuals of up to 45 years of age have been identified. However, mildly affected children also have been identified, raising the possibility of undiagnosed individuals living a relatively healthy and normal lifespan.

Treatment: No effective treatment is possible at this time. Supportive care is aimed at providing the affected child with comfort.

Reviewed by Dr. Joel Charrow, Children's Memorial Hospital.
1/03

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This page last updated on January 10, 2003.