Mitochondrial DNA structure of an isolated Tunisian Berber population and its relationship with Mediterranean populations.

BACKGROUND

Douiret is an isolated Berber population from South-Eastern Tunisia. The strong geographic and cultural isolation characterising this population might have contributed to remarkable endogamy and consanguinity, which were practiced for several centuries.

AIM

The objective of this study is to evaluate the mitochondrial DNA (mtDNA) genetic structure of Douiret and to compare it to other Mediterranean populations with a special focus on major haplogroup T.

SUBJECTS AND METHODS

Genomic DNA was extracted from blood samples of 58 unrelated individuals collected from the different patrilineal lineages of the population. The hypervariable region 1 of the mtDNA was amplified and sequenced. For comparative analyses, additional HVS1 sequences (n = 4857) were compiled from previous studies.

RESULTS

The maternal background of the studied sample from Douiret was mainly of Eurasian origin (74%) followed by Sub-Saharan (17%) and North African (3%) lineages. Douiret harbours the highest frequency of haplogroup T in the Mediterranean region, assigned to the unique subclade T1a (38%). Phylogenetic analysis showed an outlier position of Douiret at the Mediterranean level.

CONCLUSIONS

The genetic structure of Douiret highlights the presence of founders, most likely of Near/Middle Eastern origin, who conquered this area during the Middle/Late Upper Palaeolithic and Neolithic dispersals.