Definition:
Mucolipidosis IV is a rare, inherited, neurodegenerative disorder caused by a deficiency of a transport channel receptor protein. This deficiency results in the accumulation of certain fatty substances known as mucolipids and mucopolysaccharides, which are long sugar chains within the cells of many tissues in the body.

In 2000, the gene responsible for this disorder was identified. Three mutations were found to result in the clinical symptoms of Mucolipidosis IV.  Two of these mutations account for more than 90% of the Mucolipidosis IV cases found in the Ashkenazi Jewish population. As a result of this discovery, accurate carrier testing and prenatal diagnosis is available for families with a history of the disorder and for couples of Ashkenazi Jewish descent.

More than 80% of those diagnosed with Mucolipidosis IV are from the Ashkenazi Jewish population. In addition, it is estimated that one in 90 Ashkenazi Jews carry the gene for Mucolipidosis IV.

Since its first medical classification in 1974, seventy cases of Mucolipidosis IV have been reported worldwide.

Symptoms:
The two most characteristic symptoms of Mucolipidosis IV are psychomotor retardation or delayed development in muscle movement and coordination, and eye abnormalities including corneal clouding and a degeneration of the retina. By the end of the affected child’s first year of life, signs of the degeneration of the central nervous system appear. The affected child displays difficulties sitting, and many do not learn to walk. By age two or three, many children affected with this disorder become progressively mentally retarded.

Symptoms include agenesis of the corpus callosum, the failure of the band of tissue connecting the two hemispheres of the brain, to develop.

Inheritance Pattern:
Mucolipidosis IV is an autosomal recessive disorder.

Life Expectancy:
Life expectancy is unknown. Individuals afflicted with Mucolipidosis IV who are 45 years of age have been identified.

Diagnosis and Testing:
Genetic testing can confirm a diagnosis in individuals suspected of having Mucolipidosis IV. Prenatal genetic testing is also available. Additionally, tissue samples can be examined under an electron microscope to search for storage bodies, known as cytoplasmic inclusions, in the cells. If these storage bodies are found, a diagnosis of this disorder may result.

Treatment:
There is no cure for Mucolipidosis IV. Treatment is limited to controlling or reducing symptoms associated with this disorder. Physical, occupational, and speech therapies may improve the affected individual’s motor and language skills. Genetic counseling is available as well.

Patient Groups:
Mucolipidosis IV Foundation
719 East 17th Street
Brooklyn, NY 11230
www.ml4.org
tel: (718) 434-5067
Randy Yudenfriend, President
ML4www@aol.com