Leukodystrophies

What is a leukodystrophy?

The leukodystrophies are a group of rare genetic disorders that affect the central nervous system by disrupting the growth or maintenance of the myelin sheath that insulates nerve cells. These disorders are progressive, meaning that they tend to get worse throughout the life of the patient. Below we describe the source of the disorders in more detail. Fact sheets on the individual leukodystrophies are also available from the United Leukodystrophy Foundation.

How are the leukodystrophies different from one another?
All leukodystrophies are a result of problems with the growth or maintenance of the myelin sheath. However, there are many genes that are important in this process. For example, some genes are involved with the synthesis of the proteins needed for the myelin, while others are required for the proper transport of these proteins to their final location in the myelin sheath that covers the axons. Defects in any of the genes (called a mutation) may lead to a leukodystrophy. However, the symptoms of the individual leukodystrophies may vary because of the differences in their genetic cause.

How do you get leukodystrophy?
Leukodystrophies are mostly inherited disorders, meaning that it is passed on from parent to child. They may be inherited in a recessive, dominant, or X-linked manner, depending on the type of leukodystrophy. The individual pages on each leukodystrophy will describe the particular pattern of inheritance for that disease. There is also a separate fact sheet describing the different genetic inheritance patterns available from the United Leukodystrophy Foundation.

There are some leukodystrophies that do not appear to be inherited, but rather arise spontaneously. They are still caused by a mutation in a particular gene, but it just means that the mutation was not inherited. In this case, the birth of one child with the disease does not necessarily increase the likelihood of a second child having the disease.

Are the leukodystrophies related to multiple sclerosis?
The leukodystrophies do share some common features with multiple sclerosis (MS). Like the leukodystrophies, MS is caused by the loss of myelin from the axons. However, the cause is different; whereas leukodystrophies are generally caused by a defect in one of the genes involved with the growth or maintenance of the myelin, MS is thought to be caused by an attack on the myelin by the body’s own immune system.

How many different leukodystrophies are there?
New leukodystrophies are always being identified. We try to keep our information as up-to-date as possible, and so the 34 leukodystrophies we have listed comprise the defined leukodystrophies to the best of our knowledge. Not all of these meet the strict criteria for the definition of a leukodystrophy. These have been marked with an asterisk. They are included because they have features that resemble the leukodystrophies.  A fact sheet on each of these diseases is available from the United Leukodystrophy Foundation.

Content (c) United Leukodystrophy Foundation, Inc.

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