Genetic relationships among Berbers and South Spaniards based on CD4 microsatellite/Alu haplotypes

Background: CD4 STR/Alu haplotype diversity, both for its qualitative and quantitative properties, has been widely used in molecular anthropology to clarify the degree of genetic relationships among human populations. Aim: CD4 STR/Alu variation was studied in two West Mediterranean samples, Andalusians from La Alpujarra region on the north side of the Gibraltar Strait and Berbers from the south, to ascertain the pattern of affinities between them. Subjects and methods: Alu and microsatellite alleles were tested in 99 Andalusians from La Alpujarra region (Southeast Spain) and 124 Middle Atlas Berbers (Morocco). Results: Two new combinations of Alu and STR alleles (75(+) and 80(-)) were found in Berbers. The CD4 STR/Alu haplotype distribution in South Spaniards is similar to that of other Europeans, the only special feature is the slight presence of the 90(+) and 130(+) typical Sub-Saharan haplotypes. The Berber sample is characterized by a high number of different haplotypes (18) with intermediate heterozygosity values (0.846) in comparison with other North African groups, and by a high frequency of the 110(-) combination that has been proposed as representative of an ancient Northwest African population. Conclusion: A geographical gradient of Sub-Saharan gene contribution has been detected in North Africa. The Middle Atlas Berbers showed an intermediate value in comparison with the high and low values found in Mauritanians and Moroccan Berbers, respectively. The analysis of the CD4 STR/Alu haplotype variation failed to indicate any particular relationship between South Spaniards and North Africans.