About Metachromatic Leukodystrophy
Metachromatic Leukodystrophy results from mutations in the ARSA gene encoding arylsulfatase A or in the PSAP gene encoding prosaposin, a required sulfatide activator protein. ARSA deficiency prevents breakdown of sulfatides, resulting in accumulation of these myelin components in oligodendrocytes, neurons, and peripheral tissues. Sulfatide accumulation triggers demyelination, neuronal dysfunction, and neuroinflammation. The pattern of sulfatide deposits creates characteristic metachromatic staining under microscopy, which is diagnostic. Disease severity correlates with residual ARSA activity: infantile forms have minimal or absent activity, late-infantile forms have very low activity, and juvenile forms have slightly higher residual activity.
The infantile form is most severe, presenting with loss of previously acquired developmental milestones, progressive loss of motor function, spasticity, and cognitive decline. Without treatment, children become severely disabled by age 3-4 years and die in early childhood. Late-infantile forms progress similarly but with a slightly later onset. Juvenile forms progress more slowly over years to decades. Adult-onset forms may present with psychiatric symptoms, cognitive decline, or progressive motor symptoms and can remain relatively stable for extended periods. MRI shows progressive white matter demyelination and atrophy. Urine analysis may show elevated sulfatides. The first FDA-approved treatment for MLD, the gene therapy Lenmeldy (atidarsagene autotemcel), was approved in March 2024. Donor stem cell transplant has been used mainly for early juvenile MLD, though the FDA's review of Lenmeldy noted it is not considered standard of care.
Common Symptoms of Metachromatic Leukodystrophy
Recognizing the signs of Metachromatic Leukodystrophy early can lead to faster diagnosis and better outcomes. Symptoms may vary in severity from person to person. If you or a loved one are experiencing any of the following, consider speaking with a specialist.
- Infantile form: loss of developmental milestones starting 6-24 months
- Progressive loss of motor function and muscle tone
- Loss of vision and hearing
- Behavioral and cognitive decline
- Seizures and spasticity
- Inability to walk or stand in later stages
Who Metachromatic Leukodystrophy Affects
Infantile-onset form (most common, 50% of cases) presents before age 2 years. Late-infantile form presents between 2-4 years. Juvenile form presents between 4 years and adolescence. Adult form (rare) presents after age 16 with slower progression. Autosomal recessive inheritance. Affects males and females equally. Occurs across all populations.
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FDA-Approved Treatments for Metachromatic Leukodystrophy
There is currently 1 FDA-approved medication for Metachromatic Leukodystrophy. These therapies represent the current standard of care and may be used alongside or compared against investigational treatments in active clinical trials.
Source: openFDA drug labeling data. This list may not include all treatments. Always consult your doctor.
Help Paying for Metachromatic Leukodystrophy Treatment
Charity funds and drugmaker programs for Metachromatic Leukodystrophy, checked at the source. Pick your insurance to see what fits.
- From a charity · United Leukodystrophy FoundationHultman Memorial Fund fundOpen
Pays for: Expenses directly related to the affected family member, based on demonstrated hardship (per 12 months), up to $500 per year.
The foundation says: “Applications are reviewed on a rolling basis as funding is available.”
Side Effect Explorer
Real-world side effect reports from the FDA Adverse Event Reporting System (FAERS). Includes both FDA-approved drugs and investigational therapies from active clinical trials. Click any drug to see what patients reported.
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Genetic Testing
Genetic testing can confirm a diagnosis, guide treatment decisions, and identify family members who may be at risk.
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Trusted Metachromatic Leukodystrophy Resources
Reputable organizations and medical references for learning more about Metachromatic Leukodystrophy, including disease registries, foundation resources, and clinical guidelines.