Apolipoprotein E/C1/C4/C2 gene cluster diversity in two native Andean populations: Aymaras and Quechuas

The APOE/C1/C4/C2 gene cluster presents high relevance in lipid metabolism and, therefore, has important epidemiological implications. Here, we study for the first time the variation patterns of 25 polymorphisms (10 short tandem repeats, STRs, and 15 single nucleotide polymorphismas, SNPs) in two native Andean samples from Bolivia (45 Aymaras and 45 Quechuas) as well as one European sample (n = 41) as external reference. We estimated diversity parameters, linkage disequilibrium patterns, population structure, and possible selective effects. In general, diversity was low and could be partly attributed to selection (probably due to its physiological importance), since the APOE/C1/C4/C2 region was highly conserved compared to the flanking genes in both Bolivians and Europeans. Moreover, the lower gene diversity in Bolivians compared to Europeans for some markers might indicate different demographic histories. Regarding the APOE isoforms, in addition to ɛ3 (94%) and ɛ4 (5%), isoform ɛ2 (1%) was also detected in Bolivians. In relation to previous hypotheses, our results support that genetic drift or founder effects rather than selection for increased cholesterol absorption are the main factors that have shaped the distribution of APOE isoforms observed in South America.