• Fabry Disease
• HAE (Hereditary Angioedema)
• MLD (Metachromatic Leukodystrophy)
• Sanfilippo Syndrome (MPS III)

• Metachromatic Leukodystrophy
  • Overview
  • Disease Process
  • Types and Symptoms
  • Diagnosis
  • Genetics Overview
  • Genetics of MLD
  • Variations in the MLD Gene
  • Management
• Personal Stories
• News Articles
• Resources

Variations in the MLD GeneNext Topic

More than 110 different variations in the MLD gene have been discovered; however, many have been seen only in single patients. Different variations in the gene result in different levels of the functional ASA enzyme and can be separated into two groups. The first group contains null alleles, or variations that result in a total lack of ASA enzyme function. The other group contains R alleles, or variations that result in a very small amount of enzyme function, as compared to normal. The effect these different variations have on ASA enzyme activity is thought to be responsible for the different types of MLD.

If a child gets two null alleles from his or her parents, infantile MLD always develops. The combination of a null allele and an R allele usually results in the juvenile form of MLD, and two R alleles generally yield the adult form of the disorder.

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