Allelic structure and distribution of 103 STR loci in a Southern Tunisian population

Genotypes of 103 short tandem repeat (STR) markers distributed at an average of 40 cM intervals throughout the genome were determined for 40 individuals from the village of BirEl Hfai (BEH). This village of approximately 31,000 individuals is localized in the south-west of Tunisia. The allele frequency distributions in BEH were compared with those obtained for individuals in the CEPH (Centre d'Etude du Polymorphisme Humain) data using a Kolmogorov-Smirnov two-sample test. Fourteen out of the 103 markers (13.2%) showed significant differences (P<0.05) in distribution between the two populations. Population heterogeneity in BEH was indicated by an excess of observed homozygosity deviations from Hardy-Weinberg equilibrium at three loci (P<0.0005). No evidence for genotypic disequilibrium was found for any of the marker pairs. This demonstrated that in spite of a high inbreeding level in the population, few markers showed evidence for a different pattern of allelic distribution compared to CEPH.