Genetic differences between Mestizo populations of Bolivia and Peru

Data on the genetic background of Peruvian and Bolivian populations is still scarce. Studies have shown that mestizos (i.e. mixed, but of predominantly Native American ancestry) present several HLA alleles originally described in genetically isolated Amerindian tribes, and that Peruvian and Bolivian mestizos are closely genetically related. Using Reverse Line Blot Assay, HLA typing for Class I (HLA-A, HLA-B, and HLA-Cw) as well as for Class II (HLA-DRB1 and HLA-DQB1) alleles was performed in 57 Bolivian mestizos. Subjects came mainly from La Paz (the main city in the Bolivian Andes) and three other important cities located in the Bolivian Central Valley (Sucre, Tarija and Tupiza). Comparison of the allele frequencies of Bolivian mestizos with available data from the literature from Peruvian mestizos, revealed that Class I HLA-Cw*01, and B*40 alleles were higher in the Peruvian mestizo group (Chi-sq = 4,87 p<0,05; and chi-sq = 7,56 p<0,01 respectively). Regarding Class II alleles, HLA-DRB1*1101 and DRB1*1302 alleles were higher in Peruvian mestizos (Chi-sq = 5,12 p<.05; chi-sq = 3,8 p = 0.05 respectively), while HLA-DQB1*0402 was significantly higher in Bolivian mestizos (Chi-sq = 47,2 p<.0001). Differences in allele frequencies, and the absence or presence of certain alleles in either group could be due to a higher grade of admixture with Andean ethnic groups in the mestizos from Bolivia and/or less rural traits and more white (Caucasian) admixture in the Peruvian mestizos reported in the literature. These findings may have an impact regarding efficacies of modern forms of immunization (DNA vaccines) in Andean population, as well as in the identification of groups at risk for certain medical conditions.