Multiple mutations are responsible for the high frequency of metachromatic leukodystrophy in a small geographic area

Am J Hum Genet. 1995 Jan;56(1):51-7.

Abstract

Metachromatic leukodystrophy is a lysosomal storage disorder caused by the deficiency of arylsulfatase A. The disease occurs panethnically, with an estimated frequency of 1/40,000. Metachromatic leukodystrophy was found to be more frequent among Arabs living in two restricted areas in Israel. Ten families with affected children have been found, three in the Jerusalem region and seven in a small area in lower Galilee. Whereas all patients from the Jerusalem region are homozygous for a frequent mutant arylsulfatase A allele, five different mutations were found in the families from lower Galilee. In patients of Muslim Arab origin, we have found a G86-->D, a S96-->L, and a Q190-->H substitution. Two different defective arylsulfatase A alleles, characterized by a T274-->M and a R370-->W substitution, respectively, have been found among the Christian Arab patients. All mutations were introduced into the wild-type arylsulfatase A cDNA. No enzyme activity could be expressed from the mutagenized cDNAs after transfection into heterologous cells. In all instances, the patients were found to be homozygous for the mutations, and four of the five mutations occurred on different haplotypes. The clustering of this rare lysosomal storage disease in a small geographic area usually suggests a founder effect, so the finding of five different mutations is surprising.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Age of Onset
  • Alleles
  • Amino Acid Sequence
  • Base Sequence
  • Cerebroside-Sulfatase / deficiency
  • Cerebroside-Sulfatase / genetics*
  • Child, Preschool
  • Cluster Analysis
  • Consanguinity
  • DNA, Complementary / genetics
  • Ethnic Groups / genetics
  • Gene Frequency
  • Genes
  • Humans
  • Infant
  • Israel / epidemiology
  • Leukodystrophy, Metachromatic / epidemiology
  • Leukodystrophy, Metachromatic / genetics*
  • Molecular Sequence Data
  • Mutation*
  • Prevalence

Substances

  • DNA, Complementary
  • Cerebroside-Sulfatase