Association of the rs4988235(C) Polymorphism, a Determinant of Lactose Intolerance, with Genetic Ancestry in Latin American Populations

Abstract

Introduction: the rs4988235(C) polymorphism is associated with lactose intolerance and exhibits heterogeneity among populations. In Europe, the T allele (lactose tolerance) is prevalent in the north, while the C allele (lactose intolerance) is common in Asia and Africa.Methods: genotypes for rs4988235 were obtained from the 1000 Genomes Project database, selecting Latin American samples (Colombians, Mexican Americans, Peruvians, and Puerto Ricans). A total of 446 ancestry-informative markers (AIMs) were used to estimate genetic ancestry proportions. Shapiro-Wilks tests were conducted, and due to non-normality, non-parametric Kruskal-Wallis and post hoc Wilcoxon tests were applied.Results: the Shapiro-Wilks test indicated significant deviations from normality for Native-American (statistic=0.8787, p<0.05) and European ancestry proportions (statistic=0.9653, p<0.05). Kruskal-Wallis analysis showed significant differences in European (statistic=26.6696, p=1.62×10−6) and Native-American (statistic=13.4306, p=0.0012) ancestry proportions among genotypes. Post hoc Wilcoxon tests indicated significant differences between Intolerant (GG) and Heterozygous (GA) genotypes for both ancestries.Conclusions: the proportions of European and Native-American ancestry vary among genotypes of the rs4988235(C) polymorphism, suggesting the effect of admixture on the distribution of lactose intolerance in Latin American populations