Frequency distribution of the 1236T>C polymorphism in the ABCB1 gene among Peruvian populations and its comparison with populations from the Americas, Asia, Europe, and Africa

Abstract

Objective: Mutations in the ABCB1 gene have an impact on the response to various drugs and may be associated with the development of neoplasms. This study explores and compares the frequency distribution of the 1236T>C polymorphism in the
ABCB1 gene among nine Peruvian populations from different geographical origins and altitudes, as well as the genotype/allele frequencies reported in populations from various continents worldwide. Materials and methods: Sampling was carried out in the following departments and localities: Lima (n = 8), Loreto–Andoas (n = 16), San Martín–Lamas (n = 16), Puno–Uros (n = 7), Puno–Taquile (n = 5), Arequipa–Chivay (n = 10), Arequipa–Cabanaconde (n = 6), Ancash–Parobamba (n = 10), and Apurímac–Andahuaylas (n = 10). Biological samples (peripheral blood and/or epithelial cells) were collected via buccal swabs. Deoxyribonucleic acid (DNA) was extracted using a standard protocol. The 1236T>C polymorphism (rs1128503) was identified using real-time polymerase chain reaction (PCR). Variables were categorized by geographical origin (coast, highlands, or jungle) and altitude (< 2,500 or > 2,500
meters above sea level [m a.s.l.]). Statistical analyses included the Hardy–Weinberg equilibrium and Pearson’s chi-square test, with a significance level of p < 0.05 and a 95 % confidence interval (95 % CI). Results: The frequency distribution of the 1236T>C
polymorphism in the ABCB1 gene was determined for the Peruvian populations studied. Across coastal, highland, and jungle regions, the heterozygous C/T genotype (associated with intermediate P-glycoprotein activity) was the most prevalent, with the
highest frequency (60 %) observed on Taquile Island (Lake Titicaca, Puno). In the overall Peruvian sample (n = 88), the frequency of the C/T genotype was 43 % at < 2,500 and 50 % at > 2,500 m a.s.l. In contrast, the homozygous C/C (normal activity) and T/T (slow activity) genotypes showed similar frequencies at < 2,500 m a.s.l. (30 % and 28 %, respectively) but differed at > 2,500 m a.s.l. (35 % and 15 %, respectively). The overall genotype distribution in the Peruvian populations studied was 47 % C/T, 33 % C/C, and 20 % T/T. The Hardy–Weinberg equilibrium achieved no statistical significance. Conclusions: The 1236T>C polymorphism in the ABCB1 gene among Peruvian populations showed a predominance of the heterozygous C/T genotype, with variations associated with geographic region and altitude. In general, the same trend was observed across countries and continents.