MLD is a rare disease, affecting about one in 50,000 people. However, promising new approaches from the fields of gene therapy and cell transplantation provide hope for the future. ASA is the enzyme responsible for breaking down sulfatide into smaller, harmless chemicals that can be eliminated or reused by the body. In MLD, the lack of proper ASA enzyme leads to a buildup of sulfatide, which causes a process called demyelination. Demyelination causes the symptoms of MLD affecting communication between nerves in the brain.
Nerves work like a system of electrical connections.
Like electrical wires, the axons are wrapped with an insulating material. The insulating material around axons is called myelin. Ordinarily, the special cells in the brain called oligodendrocytes insulate, or myelinate, the axons. In MLD, however, sulfatide accumulates and interferes with the oligodendrocytes' myelination of the axons. The axons lose their myelin insulation, or demyelinate.