RESUMO
Objective: The aim of this study was to investigate the frequency of the LCT*-13910C>T polymorphism associated with a high expression of lactase in the small intestine during adulthood, and to infer the lactase persistence and adult-type hypolactasia phenotypes among Euro-Brazilians and Mennonites from South Brazil
Materials and Methods: A sequence-specific PCR method to genotype the LCT*-13910C>T polymorphism in 292 Euro-Brazilians and 151 Mennonites [a group with European ancestry and a long history of endogamy] was developed. Using an exact test of population differentiation, the genotype and allele frequency between these and other Brazilian populations were compared
Results: The frequency of -13910*T was significantly higher among the Mennonites when compared to the Euro-Brazilian cohort [0.63 vs. 0.33, p < 0.000001]. Accordingly, Mennonites had a higher prevalence of the lactase persistence genotype [88.1 vs. 55.5%, p < 0.000001]. The distribution of -13910*T differed between Mennonites and all other Brazilian groups [p < 0.0001]. The Euro-Brazilians from Curitiba displayed differences when compared to all other Brazilian groups [p < 0.0001], even to Euro-Brazilians from a different geographic region [p = 0.0003], but were similar to those from Porto Alegre [p = 0.2]
Conclusion: Differences in the -13910*T-associated lactase persistence distribution among Euro-Brazilian groups reflect the ancestry and admixture of each particular group and should be considered for adult-type hypolactasia screening