What is MLD?

MLD is short for Metachromatic Leukodystrophy. Translated from doctor talk MLD means: meta - change, chromatic - color, leuko - white matter, dystrophy - degeneration. MLD's name comes from degeneration in the white matter of the brain and Central Nervous System (CNS.


People who are affected by MLD lack an enzyme in their blood called Arylsulfatase-A, (ARSA). Without this enzyme, sulfatides are NOT broken down and instead build-up in the white matter of the brain and CNS causing destruction of the myelin sheath( the myelin sheath is like the coating of an electrical cord it holds everything together making current run better), or demyelination. Without an intact myelin sheath there is a breakdown in communication between the nerves and the brain. The loss of, or miscommunication accounts for the loss of acquired functions, paralysis, blindness, seizures and eventual death seen in MLD

Types of MLD

Generally, there are considered to be three main types of MLD that have different ages of onset: late-infantile, juvenile, and adult. The late-infantile form of MLD is the most commonly observed form of MLD. The most common gene mutations have been identified for both the late-infantile and the adult onsets, however, there are many other less common mutations.
MLD is not contagious and cannot be passed to others through any sort of contact - it is a genetic condition.
  • Late infantile MLD symptoms usually begin by ages 1 - 2.
  • Juvenile MLD symptoms usually begin between ages 4 and 12.
  • Adult (and late-stage juvenile MLD) symptoms may occur between age 14 and adulthood (over age 16), but may begin as late as the 40s or 50s.

    In the late infantile form, which is the most common form of MLD (50-60%), affected children begin having difficulty walking after the first year of life, usually at 15–24 months. Symptoms include muscle wasting and weakness, muscle rigidity, developmental delays, progressive loss of vision leading to blindness, loss of hearing, convulsions, seizures, the inability to swallow, paralysis, and dementia. Children may become comatose.  Most children with this form of MLD die by age 5, often much sooner.

Therapies & Research

At this time there is no cure for MLD. The only treatment is bone marrow transplant (BMT) or stem cell transplant (SCT), and they are most effective in slowing the disease in people who are pre-symptomatic, suffer from the juvenile form or the adult for of the disease. It is not a treatment option for children suffering from the late infantile form of the disease and already showing symptoms.

Transplant outcomes for late-infantile MLD

Most transplants that have been done to treat young children with the late-infantile form of MLD have not been successful in preventing severe damage. This is because the late-infantile form gets worse quickly once problems have developed. However, some children with late-infantile MLD have benefited from a transplant. [1] Good results are more likely when a transplant is done early, before symptoms appear. Most children who are diagnosed early are tested for MLD because they have an older sibling affected with the disorder.

Treatment for children with this type of MLD is symptomatic and focuses on providing the child with comfort and pain management.

Research is making strides towards the areas of improved bone marrow transplants, enzyme replacement therapy, gene therapy, and cell line studies, but unfortunately no one has successfully cured this disorder.

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  1. This information was copied from MLD Foundation www.mldfoundation.org/mld-101-what.html ... © MLD Foundation

    Please visit the MLD Foundation for up to date information about MLD newborn screening, research, and clinical trials.