Human mitochondrial DNA sequence variation in the Moroccan population of the Souss area

Background: Various populations have contributed to the present-day gene pool of Morocco, including the autochthonous Berber population, Phoenicians, Sephardic Jews, Bedouin Arabs and sub-Saharan Africans. Objective: The primary objective of the study was to complete a genetic description of the Berber-speaking population in the Souss region of southern Morocco, based on mitochondrial DNA (mtDNA) sequence analysis. Subjects and methods: The first hypervariable segment of the mtDNA control region was sequenced in a sample of 50 individuals from the Souss Valley, and the results compared with the extensive body of data available on mtDNA sequence variation in Europe and sub-Saharan Africa. Results: Thirty-four different sequences were found; an estimated 68% of the sequences occurred throughout Europe, West Asia and North Africa, 26% originated in sub-Saharan Africa, and 6% belonged to the North African specific haplogroup U6. The Souss Valley mtDNA sequences indicated the presence of two populations which expanded at different times: the West Eurasian sequences in the Souss sample had a smaller average number of pairwise differences than pairs of sub-Saharan sequences. Conclusion: Detailed knowledge of the possible geographic origin of each sequence facilitated an interpretation of both internal diversity parameters and between-population relationships. The sub-Saharan admixture in the Souss Valley matched the south-north cline of sub-Saharan influence in North Africa, also evident in the genetic distances of North African populations to Europeans and sub-Saharan Africans.