MLD- Metachromatic Leukodystrophy means: meta – change, chromatic – color, leuko – white matter, dystrophy – degeneration. MLD’s name therefore comes from degeneration in the white matter of the brain and Central Nervous System (CNS) which has a color on staining that should not be there. Staining was how the disease was observed before the advent of the MRI.

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, or demyelination. Without an intact myelin sheath there is a breakdown in communication between the nerves and the brain. This loss or miscommunication accounts for the loss of acquired functions, paralysis, blindness, seizures and eventual death seen in 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.

Today, new advances in research are giving new hope to people affected by the disease.