Anthropological analysis of Tunisian populations as inferred from HLA class I and class II genetic diversity: A meta-analysis

- Except for Berbers of Djerba, all the Tunisian populations are closely related to one another.
- Tunisians are very close to North Africans and Iberians but not to Eastern Mediterraneans
- Berbers of Djerba Island are close to Eastern Mediterraneans.
- The contribution of Arabs and Blacks to genetic pool of Tunisians was probably low.

Despite their importance, anthropological meta-analyses which allow for comprehensive evaluation of the relationships of a given population were rare. This meta-analysis evaluates the origin of Tunisians using polymorphic profile of HLA class I (A, B), and class II (DRB1, DQB1) genes, in historical, social and cultural context, and is the only analysis in the Middle East-North Africa (MENA) region. A total of 20 eligible populations were selected from several databases, and included representing 2553 Tunisian individuals, who were compared with Mediterranean and sub-Saharan populations. In total, 204 HLA alleles were detected in Tunisians, which comprised 54 HLA-A, 76 HLA-B, 50 DRB1, and 24 DQB1 alleles. The most frequent alleles were A*02:01(24.72%) in Berbers of Zrawa, B*50:01 (13.90.11%) in Tunisian-So, DRB1*07:01 (28.66%) in Ghannouchians, and DQB1*02:01 (42.79%) in Tunisians-H. The A, B, DRB, and DQB1 genotypes of 420 individuals were further subjected to a selection study. Despite the relatively large sample size, the loci depicted non-significant negative Fnd values, an indication of overall trend to balancing selection or gene flow. Except for Berbers of Djerba, dendrograms, correspondence analyses, genetic distances and haplotype analysis demonstrated the close relatedness of Berbers, Southern and Northern Tunisians, and strong relatedness was evident to Western Mediterranean, North African and Iberian populations, but not Sub-Saharans and Eastern Mediterranean populations, including Arabs. Collectively, this suggests that the contribution of Arabs and sub-Saharans to the present Tunisian gene pool is low. In addition, all Mediterranean populations depict a typical Mediterranean substratum, except for Greeks.