New insights into the genetic history of Tunisians: Data from Alu insertion and apolipoprotein E gene polymorphisms

Background: Among polymorphisms of non-transcribed DNA sequences and functional genes, those of Alu insertions and that of the APOE gene have been widely used to clarify the degree of genetic relationships between human populations. Aim: APOE gene and eight Alu insertion polymorphisms were investigated in Tunisians and compared with data from neighbour populations in order to gain new insights into the genetic position of Tunisia in the Mediterranean region. Subjects and methods: A total of 121 individuals from the North and Centre-South regions were sampled. Results: No significant genetic differences were found between Tunisians and North Africans when samples representative of wide areas were considered. APOE gene variation seemed slightly less powerful than the Alu polymorphisms in detecting North-South Mediterranean differences. Conclusion: North African populations show a substantial degree of genetic homogeneity, which may reflect the similarity of their origins, mainly when samples from large geographical areas are compared. The relative genetic homogeneity of the whole Mediterranean region probably reflects a common origin and/or remarkable levels of gene flow. However, this gene flow has not yet erased the differentiation between the two Mediterranean shores, as revealed by Alu insertion polymorphisms.