Metachromatic leukodystrophy (MLD) is the most common subgroup of the leukodystrophies, a group of disorders that affects the white matter or myelin sheath. MLD is associated with the accumulation of cerebroside sulfates, a group of myelin lipids (fats); it leads to staining (metachromasia) of brain and other nervous tissue that does not occur in other leukodystrophies. MLDs are genetic and generally marked by the absence or near-absence of the enzyme arylsulfatase A.
A type of hereditary leukodystrophy caused by a deficiency of the enzyme cerebroside sulfatase, an enzyme that is essential for the degradation of sulfatide. Deficiency of the enzyme allows excess deposition of sulfatide in nerve tissues. Clinical signs of this disease usually appear at about 1 year of age. They include gait disturbance, inability to learn to walk, spasticity of the limbs, hyperreflexia, dementia, and eventually death. The disease, for which there is no specific therapy, is usually fatal by age 10.