HLA class I and class II polymorphism in a population from south-eastern Tunisia (Gabes Area)

Abstract

The gene frequencies of HLA class I and class II alleles were investigated in 95 healthy Tunisian individuals from Gabes. Our aim was to compare the genetic relationship between Gabesians and Mediterraneans and sub-Sahara Africans using genetic distances, Neighbour-Joining dendrograms, correspondence and haplotypes analysis, thereby providing additional information about evolutionary history of modern-day Tunisians. Subjects were unrelated and of both genders, and HLA class I and class II genes were genotyped using the polymerase chain reaction-sequence specific primer (PCR-SSO) technique. Our data show that south-eastern Tunisians (Gabes area) are related to present-day North Africans (Algerians, Moroccans, Tunisians) and Iberians (Spaniards, Basques), and along with other North Africans, appear to be genetically related to Berbers, an indication that the Arab invasion (7th-11th centuries) of North Africa had minimal contribution on the HLA makeup of North Africans. On the other hand, Iberians including Spaniards and Basques show relatedness to (native Tunisian) Berbers, suggesting that the gene flow of 7th century AD invaders was also low in Iberians. In conclusion, the successive invasions of North Africa in general, and Tunisia in particular, did not modify markedly the genetic makeup of present-day Tunisians. With the exception of Greeks who have a sub-Saharan genetic profile, all Mediterranean populations depict a typical mediterranean substratum.

HLA-A, -B, -C, -DRB1, -DQA1, and -DQB1 allele and haplotype frequencies defined by next generation sequencing in a population of East Croatia blood donors

“…A strong influence of south-eastern European populations on the HLA makeup of eastern Croats was further supported by the high prevalence of the HLA-B*27:02:01:01 variant, which fits well into the B*27:02 frequency gradient diminishing from the Middle East towards the Central and West European countries. In support, the observed B*27:02:01:01 frequency (3.6%) seems to be in close agreement with the B*27:02 cline extending across the south-eastern Tunisian (5.8%) 33 , Bulgarian (4.6%) 34 , CBMDR (2.14%) 17 , Czech (1.9%) 9 , and Polish (1.5%) 35 populations. The B*44:27:01 allele, an east European marker considered a rare variant according to the "Rare Alleles Detector" tool 9 , was also noticed in our cohort at a relatively high frequency (2.7%), contrasting observations from Croatian HSCT patients (1.18%) 19 , Czech National Marrow Donors Registry (0.69%) 9 , as well as Polish (0.8%) 35 , English (0.19%) 36 , and Argentinian blood donors (0.07%) 37 .…”

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

“…A high frequency of DRB1*03:01 (15.6%) allele was observed in Tunisia, which was comparable to frequencies established earlier for Moroccans (17.3%) [ 36 ], Tunisians (15.1%) [ 33 ], Algerians, and some European populations [ 37 ] including Spanish Basques (19.3%) [ 25 ]. At the DQB1*locus, 21 alleles were detected, of which DQB1*03:01 was the most frequent (18.0%), followed by DQB1*02:01(16.8%) and DQB1*02:02 (15.2%), which were also reported for Tunisians elsewhere [ 33 – 35 , 38 ]…”

“…These haplotypes were common in Mediterranean populations. Indeed, the DRB1*03:01-DQB1*02:01 haplotype was found in Northern Tunisians (14.08%) [ 33 ], Ghannouchians (17.66%) [ 35 ], Gabesians (18.42%) [ 38 ], Tunisian Berbers (11.26%) [ 34 ], Algerians (11.3%) [ 27 ], Basques (17.5%) [ 25 ], Moroccans (17.3%) [ 24 ] and Cretans (7.4%) [ 41 ]. Besides, DRB1*07:01-DQB1*02:02 was also present in Ghannouchians (16.46%) [ 35 ], Northern Tunisians (9.71%) [ 33 ], Tunisian Berbers (16.03%) [ 34 ], Spaniards (17.3%) [ 42 ] and Moroccans (12.6%) [ 24 ].…”

“…The most frequent haplotype found in Tunisian population, A*02:01–B*50:01–DRB1*07:01–DQB1*02:02 (2.2%), was also found in Tunisian Berbers (8.1%) [ 34 ], Gabesians (2.6%) [ 38 ], Northern Tunisians (1.2%) [ 33 ], Ghannouchians (1.8%) [ 35 ], Spaniards (1.2%) [ 42 ], Italians (0.5%), Turks (1.3%) and Moroccan Jews (2%) [ 43 – 45 ]. In addition, A*24:02-B*08:01-DRB1*03:01-DQB1*02:01 haplotype (1.6%) is found in Gabesians (1.6%) [ 38 ], Ghannouchians (4.2%) [ 35 ], and frequently associated with A*1 in Southern Tunisians [ 46 ], Mediterraneans and in Spaniards (3.4%), Basques (5%), Macedonians (4.9%), Yugoslavians (7.7%) [ 18 , 39 , 43 , 47 ]. A*34:02–B*44–DRB1*15:01–DQB1*06:02 haplotype (4.25%) [ 34 ], which characterizes Tunisian Berbers, was detected in the present Tunisian population at lower frequency (0.8%).…”

Genetics and genomic medicine in Tunisia

“…This haplotype was also present in Tunisian Berbers (16.03%) (Hajjej, Almawi, Hattab, El‐Gaaied, & Hmida, ). In fact, the HLA class II allele DRB1*07:01 was present at 22.06% in the southern population, and was detected at high frequencies in Tunisian Berbers (17.6%) and in Ghannouchians (28.7%) occupying a village situated at the eastern south of Tunisia and characterized by high endogamy, behaving like an isolate (Hajjej, Hajjej, et al., ).…”