Variable onset of metachromatic leukodystrophy in a Vietnamese family.

We report two siblings with metachromatic leukodystrophy, one who presented at 7 years of age (juvenile onset) and his sister who presented at 22 years of age (adult onset). They are compound heterozygotes for two novel mutations in the arylsufatase A gene (ARSA). The responsible mutations in this Vietnamese family consist of a missense mutation with 5% enzyme activity (R143G) and a nonsense mutation (W318ter), from which no enzyme activity would be expected. These mutations in the ARSA gene have not been previously reported and may be useful when diagnosing metachromatic leukodystrophy in other affected Vietnamese individuals. The variability in presentation suggests that the genotype alone is not sufficient to determine the onset and course of the disease and modifying genetic and perhaps nongenetic factors likely contribute.