Metachromatic leukodystrophy (MLD) is an inherited storage disorder resulting from a deficiency of arylsulfatase A, an enzyme which is needed to break down certain types of fat-based compounds in the body. When the body cannot break down (metabolize) these fat-based compounds, then they build up and can damage the brain, nervous system, bones and other tissues.
MLD may present late-infantile form (early-onset, ages 05-4 years), early juvenile form (late onset, 4-6 years), late juvenile form (late onset, 6-16 years), and adult form (late onset, >16 years). MLD is rare. The experience with transplant for MLD remains very challenging. All patients transplanted for symptomatic late infantile MLD have done poorly in all aspects. The few cases of presymptomatic transplant for late-infantile MLD have shown preservation of cognitive function, but not motor function. These children have become wheelchair bound and totally dependent in activities of daily living. Similar disappointing results have been observed among those transplanted for juvenile and adult form of the disease with all patients demonstrating disease progression after transplant.