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

<b>Background:</b> 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. <b>Aim:</b> 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. <b>Subjects and methods:</b> 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 (<i>n</i> = 4857) were compiled from previous studies. <b>Results:</b> 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. <b>Conclusions:</b> 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.

<b>背景：</b>杜伊雷特（Douiret）是突尼斯东南部一个与世隔绝的柏柏尔族群。该族群因强烈的地理与文化隔绝特征，或促成了显著的内婚制与血缘婚配现象，该习俗已延续数百年之久。<b>研究目的：</b>本研究旨在解析杜伊雷特人群的线粒体DNA（mtDNA）遗传结构，并将其与其他地中海人群进行比较，重点聚焦于主要单倍群T（haplogroup T）。<b>研究对象与方法：</b>本研究从该族群不同父系世系中收集了58名无亲缘关系个体的血液样本，提取其基因组DNA。对线粒体DNA高变区1（HVS1）进行扩增与测序。为开展对比分析，我们从既往研究中整合了额外的HVS1序列（n=4857）。<b>研究结果：</b>杜伊雷特研究样本的母系遗传背景主要源自欧亚大陆支系（74%），其次为撒哈拉以南非洲支系（17%）与北非支系（3%）。杜伊雷特人群拥有地中海地区最高的单倍群T频率，该单倍群隶属于独特的亚支系T1a，占比达38%。系统发育分析显示，在地中海人群范围内，杜伊雷特人群呈现出独特的离群地位。<b>研究结论：</b>杜伊雷特人群的遗传结构表明存在奠基者群体，其起源大概率为近东/中东地区，这些群体在中/晚旧石器时代晚期与新石器时代的迁徙浪潮中进驻该区域。