1. ¹Unitat d'Antropologia, Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain
2. ²Centre d'Anthropologie, University Toulouse III, Toulouse, France
3. ³Department of Biology, University of Crete, Herakleion, Greece
4. ⁴Faculte de Pharmacie de Monastir, Universite du Centre, Monastir, Tunisia

Correspondence: Professor P Moral, Department Biologia Animal-Antropologia, Faculty Biologia, Universidad de Barcelona, Avenue Diagonal 645, Barcelona 08028, Spain. Tel: +34 934021461; Fax: +34 934035740; E-mail: pmoral@ub.edu

Received 28 September 2006; Revised 19 January 2007; Accepted 24 January 2007; Published online 28 February 2007.

Abstract

Alu elements are the most abundant mobile elements in the human genome (1 100 000 copies). Polymorphic Alu elements have been proved to be useful in studies of human origins and relationships owing to two important advantages: identity by descent and absence of the Alu element known to be the ancestral state. Alu variation in the X chromosome has been described previously in human populations but, as far as we know, these elements have not been used in population relationship studies. Here, we describe the allele frequencies of 13 'young' Alu elements of the X chromosome (Ya5DP62, Ya5DP57, Yb8DP49, Ya5a2DP1, Yb8DP2, Ya5DP3, Ya5NBC37, Yd3JX437, Ya5DP77, Ya5NBC491, Yb8NBC578, Ya5DP4 and Ya5DP13) in six human populations from sub-Saharan Africa (the Ivory Coast), North Africa (Moroccan High Atlas, Siwa oasis in Egypt, Tunisia), Greece (Crete Island) and Spain (Basque Country). Eight out of 13 Alu elements have shown remarkably high gene diversity values in all groups (average heterozygosities: 0.342 in the Ivory Coast, 0.250 in North Africa, 0.209 in Europe). Genetic relationships agree with a geographical pattern of differentiation among populations, with some peculiar features observed in North Africans. Crete Island and the Basque Country show the lowest genetic distance (0.0163) meanwhile Tunisia, in spite of its geographical location, lies far from the other two North African samples. The results of our work demonstrate that X chromosome Alu elements comprise a reliable set of genetic markers useful to describe human population relationships for fine-scale geographical studies.