Leukodystrophy Health Article

Diagnosis

Leukodystrophies are occasionally misdiagnosed as muscular dystrophy, since they all are neurological disorders involving white matter. Genetic testing is usually in order for all leukodystrophies except Alexander's disease and Van der Knapp syndrome for which the specific genetic abnormalities are unknown. A nerve conduction velocity (NCV) test is sometimes used to evaluate nerve damage in people with metachromatic leukodystrophy. The NCV test sends small electrical shocks through one end of a nerve. The time it takes to travel to the other end of the nerve is measured to help determine the severity of nerve damage. Diagnosis of CTX is made by measuring the levels of bile alcohol in the blood or urine, or of cholestanol in the blood. Cholestanol is similar chemically to cholesterol but can be distinguished from it by special chemical tests. MLD and Van der Knapp syndrome diagnosis are usually made by a brain imaging scan called magnetic resonance imaging (MRI). A series of biochemical tests is sometimes used to diagnose MLD.

Treatment and management

With the exception of CTX, none of the leukodystrophies covered here are treatable. In some of the disorders, specific symptoms can be treated. For example some infections associated with MLD, such as pneumonia, can be treated with antibiotics. In ovarioleukodystrophy syndrome, ovarian insufficiency can be treated with hormone replacement therapy. But there are no treatments available for most of the conditions associated with leukodystrophies, such as mental retardation, dementia, deterioration of speech, vision, and mobility, and degeneration of myelin (white matter). In CTX, administration of certain bile acids, especially chenododeoxycholic acid, can prevent further progression of the disorder and in some cases may bring improvement.

Prognosis

The prognosis varies between leukodystrophy types but overall, most people with leukodystrophy can expect a shortened life span. Infants with Alexander's disease generally do not live past the age of five or six. Infants with metachromatic leukodystrophy (MLD) usually do not live past age 10. In children and adults, Alexander's disease and MLD progress more slowly but life expectancy is still shortened. Life expectancy with CACH is also shortened, with few people living beyond age 40 years. CADASIL progresses slowly but death occurs on average about 21–22 years after onset of symptoms. Life expectancy is closer to normal with CTX provided it is diagnosed and treated early. Ovarioleukodystrophy is a relatively newly identified disorder and there is not enough information available to make a prognosis of life expectancy, other than to say it is probably reduced. The average life expectancy is also unknown for Van der Knapp syndrome; several patients have died in their 20s but others are still alive in their 40s.

A number of government agencies and private foundations are currently funding research into many of the leukodystrophies, including identifying the cause of individual disorders, developing therapies to prevent disease progression, and to prevent onset of disease. However, little research is being done on therapies to repair damage already done by the disorders, or of restoring functions lost because of the disorders, according to The Myelin Project, a private research foundation.

BOOKS

Scheltens, P. White Matter Disease. Basel, Switzerland: S. Karger Publishing AG, 1999.

ORGANIZATIONS

National Organization for Rare Disorders (NORD). PO Box 8923, New Fairfield, CT 06812-8923. (203) 746-6518 or (800) 999-6673. Fax: (203) 746-6481. <http://www.rarediseases.org>.

United Leukodystrophy Foundation. 2304 Highland Dr., Sycamore, IL 60178. (815) 895-3211 or (800) 728-5483. Fax: (815) 895-2432. <http://www.ulf.org>.

WEBSITES

The Myelin Project. <http://www.myelin.org>.

Delayed Myelin. Myelin Associated Infant-Childhood Development Disorders. <http://www.delayedmyelin.homestead.com>.

Ken R. Wells