Modifying Role of GSTP1 Polymorphism on the Association between Tea Fluoride Exposure and the Brick-Tea Type Fluorosis.

Junhua Wu,Jing Sun,Yang Liu,Jing Cui,Wei Wang,Mang Li,Xiaona Liu,Yanmei Yang,Zhenqi Sun,Hongxu Liu,Yanhui Gao,Yan Ye,Bingyun Li,Dianjun Sun,Joseph Devaney

doi:10.1371/journal.pone.0128280

Abstract

BackgroundBrick tea type fluorosis is a public health concern in the north-west area of China. The association between SNPs of genes influencing bone mass and fluorosis has attracted attention, but the association of SNPs with the risk of brick-tea type of fluorosis has not been reported.ObjectiveTo investigate the modifying roles of GSTP1 rs1695 polymorphisms on this association.MethodsA cross-sectional study was conducted. Brick-tea water was tested by the standard of GB1996-2005 (China). Urinary fluoride was tested by the standard of WS/T 89-2006 (China). Skeletal fluorosis was diagnosed by X-ray, the part we scheduled was forearm, shank, and pelvic, then diagnosed the skeletal fluorosis by the standard of WS/192-2008 (China). Gene polymorphism was tested by Sequenom MassARRAY system.ResultThe prevalence rate in different ethnical participants was different: Tibetan individuals had the highest prevalence rate of skeletal fluorosis. There were significant differences in genotype frequencies of GSTP1 Rs1695 among different ethnical participants (p<0.001): Tibetan, Mongolian and Han subjects with homozygous wild type (GSTP1-AA) genotype were numerically higher than Kazakh and Russian subjects (p<0.001). Compared to Tibetan participants who carried homozygous A allele of GSTP1 Rs1695, Tibetan participants who carried G allele had a significantly decreased risk of skeletal fluorosis (OR = 0.558 [95% CI, 0.326-0.955]). For Kazakh participants, a decreased risk of skeletal fluorosis among carriers of the G allele was limited to non high-loaded fluoride status (OR = 0. 166 [95% CI, 0.035–0.780] vs. OR = 1.478 [95% CI, 0.866–2.552] in participants with high-loaded fluoride status). Neither SNP-IF nor SNP-age for GSTP1 Rs1695 was observed.ConclusionThe prevalence rate of the brick tea type fluorosis might have ethnic difference. For Tibetan individuals, who had the highest prevalence rate, G allele of GSTP1 Rs1695 might be a protective factor for brick tea type skeletal fluorosis.

Highlights

Skeletal fluorosis is a chronic metabolic bone and joint disease, which is caused by long-term exposure to excessive amounts of fluoride [1]
For Tibetan individuals, who had the highest prevalence rate, G allele of GSTP1 Rs1695 might be a protective factor for brick tea type skeletal fluorosis
We investigated the potential for GSTP1 Rs1695 Single nucleotide polymorphism (SNP)-fluoride exposure interactions (Table 5)

Summary

Introduction

Skeletal fluorosis is a chronic metabolic bone and joint disease, which is caused by long-term exposure to excessive amounts of fluoride [1]. It is a serious public health problem in many parts of the world where drinking water or foods contains more fluoride [1,2,3,4,5]. The brick-tea type of fluorosis has been reported in minority regions of the western and northern parts of China, where brick-tea is a traditional drink and consumed in large quantities [15, 16]. The association between SNPs of genes influencing bone mass and fluorosis has attracted attention, but the association of SNPs with the risk of brick-tea type of fluorosis has not been reported

Methods

Findings

Discussion

Conclusion