Interaction of calcitonin receptor gene polymorphisms and environmental factors in the population lived in coal-burning.borne endemic fluorosis areas in Chongqing Jiang

Abstract

Objective To explore the interaction of calcitonin receptor （CTR） gene polymorphisms and environmental factors in the population lived in coal-burning-borne endemic fluorosis areas in Chongqing. Methods A 1 ： 1 case-control study was carried out and Duping Township of Wushan County and Xinglong Township of Fengjie County of Chongqing were chosen as dae endemic fluorosis areas. The observation subjects were divided into case group 121 cases and internal control group 130 cases. The Alu I polymorphism in the CTR gene was genotyped using the PCR-RFLP procedure. Logistic regression model was used to analyze the environment and genetic factors, and the interaction between genes and environment was.determined according to interaction indicators. Results The rate of CC genotype in case group was lower than that of the control group [60.33% （73/121） vs. 74.62% （97/130） ], while theTY genotype was higher than that of the control group[9.09% （11/21） vs. 3.85%（5/130）]. Significant differences in Alu I genotypes were observed between groups （χ2 = 6.57, P = 0.037 〈 0.05; 95%CI： 0.029 - 0.036）. Allele frequencies of CTR genotypes differed significantly between groups（χ2= 7.67, P = 0.006 〈 0.01; OR = 0.53,95%CI： 0.338 - 0.834）. Urinary fluoride level（≥1 mg/L） was demonstrated to be a risk factor of fluorosis（OR = 1.814,P = 0.041 〈 0.05）. There was a positive interaction（OR = 5.530,γ= 2.457） between CT ＋TT genotypes in CTR and the fluorosis environment of the people （urinary fluoride level ≥ 1 mg/L）.Conclusions There is a certain type of interaction between CTR gene C/T polymorphism and environmental fluorine content （urinary fluoride ≥ 1 mg/L） in Chongqing population lived in coal-burning-borne fluorosis areas, and the onset of fluorosis is the result of interaction between heredity and environment. Key words: Fluorosis ; Polymorphism ; Calcitonin receptor; Genetic ; Interaction