Leukodystrophies are a group of genetic diseases that affect the white matter in the central nervous system (the brain and spinal cord). White matter is tissue that contains nerve fibers, or axons. The protective covering around these nerve fibers is called myelin. Myelin helps the nerves throughout your body communicate with each other.
When you have a leukodystrophy, there are abnormalities in the white matter in your central nervous system. This damages the myelin, disrupting communication between your brain and your body.
Leukodystrophies are rare. Altogether, they occur in about 1 of 4700 live births. A leukodystrophy can show up at any time from birth to late adulthood, but they are more common in children. Most leukodystrophies are progressive, which means they get worse and cause more damage as time goes on.
Types of leukodystrophies
Right now, there are more than 50 different conditions that are considered to be leukodystrophies.
Some of the specific types of leukodystrophy include:
- Alexander disease
- Canavan disease
- Cerebrotendinous xanthomatosis (CTX)
- Krabbe disease
- Metachromatic leukodystrophy (MLD)
- Pelizaeus-Merzbacher disease (PMD)
- Refsum disease
- Vanishing white matter disease (also known as childhood ataxia with central nervous system hypomyelination)
- X-linked adrenoleukodystrophy (ALD)
Signs & symptoms of leukodystrophies
In some leukodystrophies, symptoms may start soon after birth or may even be detected prenatally. In others, they may not show up until later childhood or even adulthood.
Each type of leukodystrophy affects different parts of the brain, so the symptoms can vary widely. This means that symptoms depend on which type of leukodystrophy your child has, how old they are, and how much the disease has progressed.
In general, symptoms in infants may include:
- Developmental delay or developmental regression (loss of previously achieved milestones)
- Abnormal eye movements
- Abnormal head growth (microcephaly or macrocphaly)
In children, adolescents, and adults, symptoms may include:
- Developmental delay or regression (loss of previously achieved milestones)
- Changes in behavior
- Cognitive problems, including problems with attention
- Vision changes
- Balance or coordination problems
What causes leukodystrophies?
Leukodystrophies happen because of a mutation in one of the genes that affects how myelin works or grows. Frequently, this mutation is inherited from one or both parents. However, sometimes leukodystrophy is caused by a spontaneous mutation that is not inherited.
As a parent, you can have a genetic mutation that’s associated with a leukodystrophy, yet not ever develop the disease yourself. But, since you have the mutated gene, you may pass it on to your children. This means you’re what’s called a carrier.
How are leukodystrophies diagnosed?
Leukodystrophies can be hard to diagnose and the process may sometimes take a long time. Getting diagnosed as soon as possible is important though because treatment can help. In some types of leukodystrophy, treatment may even be able to prevent further damage.
Many states include some leukodystrophies in newborn screenings. You can check with your child’s pediatrician to find out which screenings your child has had.
If your child has symptoms of a leukodystrophy, they may have tests to help diagnose it or to rule out other conditions. These tests may include:
- Magnetic resonance imaging (MRI) to look at your child’s brain and spinal cord
- Genetic testing
- Tests to see how your child’s muscles and the nerves that control them are working
- Tests that check for hearing and vision loss
- Other blood tests
Treatment for leukodystrophies
Leukodystrophies are progressive, meaning they usually get worse with time. Your child’s prognosis will depend on what type of leukodystrophy they have.
Leukodystrophy has no cure. Your medical team will work to treat your child’s symptoms. Depending on which type of leukodystrophy your child has, some of the treatments they might have include:
- Anti-epileptic medications to prevent seizures
- Medication to help with tight muscles and movement issues
- Physical, occupational, and/or speech therapy to improve mobility, speaking, and balance
- Nutritional therapy to help with eating and swallowing difficulties
Stem cell or bone marrow transplantation may help improve certain types of leukodystrophy.
If it’s diagnosed early, one type of leukodystrophy called CTX can be treated with chenodeoxycholic acid (CDCA) replacement therapy.
Researchers are conducting trials to study new treatment options such as gene therapy, enzyme replacement, and certain medications.