HLA Class I and Class II Alleles and Haplotypes Confirm the Berber Origin of the Present Day Tunisian Population

Abstract

In view of its distinct geographical location and relatively small area, Tunisia witnessed the presence of many civilizations and ethnic groups throughout history, thereby questioning the origin of present-day Tunisian population. We investigated HLA class I and class II gene profiles in Tunisians, and compared this profile with those of Mediterranean and Sub-Sahara African populations. A total of 376 unrelated Tunisian individuals of both genders were genotyped for HLA class I (A, B) and class II (DRB1, DQB1), using reverse dot-blot hybridization (PCR-SSO) method. Statistical analysis was performed using Arlequin software. Phylogenetic trees were constructed by DISPAN software, and correspondence analysis was carried out by VISTA software. One hundred fifty-three HLA alleles were identified in the studied sample, which comprised 41, 50, 40 and 22 alleles at HLA-A,-B,-DRB1 and -DQB1 loci, respectively. The most frequent alleles were HLA-A*02:01 (16.76%), HLA-B*44:02/03 (17.82%), HLA-DRB1*07:01 (19.02%), and HLA-DQB1*03:01 (17.95%). Four-locus haplotype analysis identified HLA-A*02:01-B*50:01-DRB1*07:01-DQB1*02:02 (2.2%) as the common haplotype in Tunisians. Compared to other nearby populations, Tunisians appear to be genetically related to Western Mediterranean population, in particular North Africans and Berbers. In conclusion, HLA genotype results indicate that Tunisians are related to present-day North Africans, Berbers and to Iberians, but not to Eastern Arabs (Palestinians, Jordanians and Lebanese). This suggests that the genetic contribution of Arab invasion of 7th-11th century A.D. had little impact of the North African gene pool.

The genetic heterogeneity of Arab populations as inferred from HLA genes

“…Using genetic distances, correspondence analysis and NJ trees, we showed earlier [ 61 , 62 ] and in this study that Palestinians, Syrians, Lebanese and Jordanians are closely related to each other and to Eastern Mediterranean Europeans (Turks, Cretans, Greeks), Egyptians and Iranians, and confirmed by HLA class I ( A , B ) and class II markers ( DRB1 and DQB1 ) analysis. However, Levant Arabs are distant from North African Arabs (Tunisians, Algerians, Moroccans and Libyans) and Iberians (Basques, Spaniards).…”

The HLA‐B landscape of Africa: Signatures of pathogen‐driven selection and molecular identification of candidate alleles to malaria protection

“…Interestingly, the FUL (included in the 29 population samples taken from published studies), who also appear as outliers in our analyses and whose genetic divergence has been observed for other genetic markers (Černý et al., ), are one of the largest nomadic pastoralist (camel herder) groups of Africa, a way of life that would have maintained them genetically isolated from neighbouring populations. Noteworthy is the genetic similarity, at locus HLA‐A (visible in the corresponding NMDS), between the FUL and the GHA (Tunisians from Gannouch), previously reported as having a “Berber substratum” (Hajjej, Almawi, Hattab, El‐Gaaied, & Hmida, ; Hajjej et al., ), which agrees with mtDNA and genomewide analyses supporting a Middle Holocene input to ancestral Fulani population from the Mediterranean area (Kulichová et al., ; Triska et al., ). Interestingly, it has also been stated that the FUL are less susceptible to malaria than neighbouring populations of Burkina Faso (Modiano et al., ), showing a higher immune reactivity which would not be due to the “classical” malaria‐resistance genes (Modiano et al., ) but to a functional deficit of T regulatory cells (Torcia et al., ) and higher levels of cytokines (Bostrom et al., ).…”

Association of HLA Class II Alleles and Haplotypes with Type 1 Diabetes in Tunisian Arabs

“…DRB1 * 08, * 09, * 12, * 14, * 16, and DQB1 * 04 were found to be rare in the sample of Tunisian population tested. It is noteworthy that this allelic distribution in controls was comparable to those previously described in healthy Tunisian population [31][32][33].…”