Arylsulfatase A pseudodeficiency: a common polymorphism which is associated with a unique haplotype

Area of Science:

• Genetics
• Biochemistry
• Population Studies

Background:

• The pseudodeficiency (PD) allele of arylsulfatase A (ARSA) is a frequent genetic polymorphism observed across diverse populations.
• This polymorphism affects lysosomal enzyme activity and is particularly prevalent in certain Israeli ethnic groups, with frequencies ranging from 9.2% to 22.7%.

Purpose of the Study:

• To investigate the genetic structure and origin of the ARSA PD allele within Israeli populations.
• To determine the association of specific mutations, PD(1) and PD(2), with the PD allele and linked genetic markers.

Main Methods:

• Screening of 660 alleles to analyze the PD allele and its associated mutations (PD(1) and PD(2)).
• Analysis of three intragenic ARSA polymorphisms to assess linkage disequilibrium.
• Haplotype analysis to identify specific genetic backgrounds associated with the PD allele.

Main Results:

• The PD(2) mutation was consistently found linked to the PD allele, whereas PD(1) can occur independently.
• Complete linkage disequilibrium was observed between the PD allele and a specific haplotype defined by three polymorphic restriction sites.
• The frequency of the PD allele varied significantly among different Israeli ethnic groups.

Conclusions:

• The findings suggest that the ARSA PD polymorphism likely originated from a single common founder or through recurrent mutations within a unique, conserved haplotype.
• The strong linkage disequilibrium provides insights into the evolutionary history and population genetics of the ARSA gene in this region.