Leukodystrophies: Rare Genetic Disorders of the Brain's White Matter

Leukodystrophies are a group of rare genetic disorders of the central nervous system — the brain and spinal cord. They damage its white matter, which is made up of:

• nerve fibers (axons), which connect nerve cells; and
• myelin, a layer of proteins and fats that covers and protects the nerve fibers and speeds signals between nerve cells.

Damaged white matter slows or blocks those signals, which can cause many problems, including trouble with movement, vision, hearing and thinking.

Types and causes

There are more than 50 types. Some are present at birth, others do not cause symptoms until a child is a toddler, and a few mainly affect adults. Most get worse over time. They are caused by genetic changes, usually inherited from a parent.

Symptoms

Symptoms depend on the type. They can include a gradual loss of muscle tone, balance and mobility, walking, speech, the ability to eat, vision, hearing and normal behavior. Other symptoms can include learning and developmental disabilities, bladder problems, breathing problems, muscle control disorders and seizures.

Diagnosis

With so many types and such varied symptoms, leukodystrophies can be hard to diagnose. A provider may use physical and neurological exams, a medical and family history, imaging such as MRI or CT scans, genetic testing and laboratory tests.

Treatment

There is no cure; treatment relieves symptoms and provides support. It may include:

• medicines for muscle tone, seizures and spasticity (muscle stiffness);
• physical, occupational and speech therapy to improve mobility, function and thinking;
• nutritional therapy for eating and swallowing problems; and
• educational and recreational programs.

Stem cell or bone marrow transplantation can help in a few types. One type, CTX, is treatable if found early, with chenodeoxycholic acid (CDCA) replacement therapy.

Sources

• MedlinePlus, U.S. National Library of Medicine, "Leukodystrophies" (summary from the National Institute of Neurological Disorders and Stroke): https://medlineplus.gov/leukodystrophies.html