Haplotype structure of five SNPs within the ACE gene in the Tunisian population.

BACKGROUND The Angiotensin-Converting Enzyme (ACE) is a candidate gene in the aetiology of several common diseases. The study of the haplotype structure of this gene is of interest in diagnosis and in pharmacogenomics. AIM The study investigated the haplotype profile of single nucleotide polymorphisms (SNPs) within the ACE gene in the Tunisian population and compared it with other populations. SUBJECTS AND METHODS Five SNPs (rs1800764, rs4291, rs4309, rs4331, rs4340) covering a region of 15.6 kb of the ACE gene were typed by PCR-digestion in a sample of 100 healthy subjects. RESULTS All SNPs were polymorphic and in Hardy-Weinberg equilibrium. A total of 21 haplotypes were identified but only eight had a frequency of more than 1%. The four most common haplotypes had a cumulative frequency of 87.4%. The 'Yin-Yang' phenomenon (the two major haplotypes are complementary at all sites) was found. Linkage disequilibrium between all pairs of loci was highly significant (p<10-5). A simple and efficient statistical procedure was used to identify three important SNPs. CONCLUSION The Tunisian population showed a different haplotype structure from the European one for the ACE gene and three important SNPs were identified. These will be very helpful in future association studies in the Tunisian and North African populations.