Frequency of LCT -13910C&gt;T single nucleotide polymorphism associated with adult-type hypolactasia/lactase persistence among Brazilians of different ethnic groups

Rejane Mattar,Maria S Monteiro,Flair J Carrilho,Aníbal F Santos,Cibele A Villares,Joyce Mk Silva

doi:10.1186/1475-2891-8-46

Abstract

BackgroundAdult-type hypolactasia, the physiological decline of lactase some time after weaning, was previously associated with the LCT -13910C>T polymorphism worldwide except in Africa. Lactase non-persistence is the most common phenotype in humans, except in northwestern Europe with its long history of pastoralism and milking. We had previously shown association of LCT -13910C>T polymorphism with adult-type hypolactasia in Brazilians; thus, we assessed its frequency among different Brazilian ethnic groups.MethodsWe investigated the ethnicity-related frequency of this polymorphism in 567 Brazilians [mean age, 42.1 ± 16.8 years; 157 (27.7%) men]; 399 (70.4%) White, 50 (8.8%) Black, 65 (11.5%) Brown, and 53 (9.3%) Japanese-Brazilian. DNA was extracted from leukocytes; LCT -13910C>T polymorphism was analyzed by PCR-restriction fragment length polymorphism.ResultsPrevalence of the CC genotype associated with hypolactasia was similar (57%) among White and Brown groups; however, prevalence was higher among Blacks (80%) and those of Japanese descent (100%). Only 2 (4%) Blacks had TT genotype, and 8 (16%) had the CT genotype. Assuming an association between CC genotype and hypolactasia, and CT and TT genotypes with lactase persistence, 356 (62.8%) individuals had hypolactasia and 211 (37.2%) had lactase persistence. The White and Brown groups had the same hypolactasia prevalence (~57%); nevertheless, was 80% among Black individuals and 100% among Japanese-Brazilians (P < 0.01).ConclusionThe lactase persistence allele, LCT -13910T, was found in about 43% of both White and Brown and 20% of the Black Brazilians, but was absent among all Japanese Brazilians studied.

Highlights

Adult-type hypolactasia, the physiological decline of lactase some time after weaning, was previously associated with the LCT -13910C>T polymorphism worldwide except in Africa
The DNA region of the LCT -13910C>T lactase persistence-non persistence variant functioned in vitro as a cis regulatory element capable of enhancing differential transcriptional activation of the lactase promoter that is consistent with a causative role in the mechanism of lactase persistence/non-persistence phenotypes in humans [6]
The LCT -13910C>T polymorphism has been associated with adult-type hypolactasia in Brazilians [7]; we assessed its frequency among different Brazilian ethnic groups

Summary

Introduction

Adult-type hypolactasia, the physiological decline of lactase some time after weaning, was previously associated with the LCT -13910C>T polymorphism worldwide except in Africa. Lactase non-persistence is the most common phenotype in humans, except in northwestern Europe with its long history of pastoralism and milking. We had previously shown association of LCT -13910C>T polymorphism with adult-type hypolactasia in Brazilians; we assessed its frequency among different Brazilian ethnic groups. Lactase non-persistence is the most common phenotype in humans, with frequencies around 65%, except in northwestern Europe with its long history of pastoralism and milking [3]. The LCT -13910C>T polymorphism has been associated with adult-type hypolactasia in Brazilians [7]; we assessed its frequency among different Brazilian ethnic groups Enattah et al (2002) identified a variant allele polymorphism LCT -13910C>T upstream from the lactase gene locus, associated with hypolactasia/lactase persistence in Finland and elsewhere [4]; an exception is Africa, with three identified single nucleotide polymorphisms: LCT -14010G>C, LCT -13915T>G, and LCT 13907C>G [5].

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