ABSTRACT
Objective To investigate the relationship between Cytochrome P-450 1A1 (CYP1A1) gene polymorphism and the ethnic differences to brick-tea fluorosis and the gene-environment interaction.Methods Inhabitants over the age of 16 years old in Inner Mongolia,Qinghai and Xinjiang were investigated.The questionnaire survey included basic information,dietary survey and total fluoride intake,and peripheral venous blood was collected.The CYP1A1 gene single nucleotide polymorphism (SNP) genotyping was determined using mass spectrometry;the diagnosis of skeletal fluorosis was based on the X-ray method;combined genetic factors with environmental factors,the interaction of gene-environment was analyzed.Results In the 1 414 copies of whole blood samples (308 Tibetans,290 Kazakhs,261 Mongolians,425 Han people,130 Russians),CYP1A1 genes rs1048943 sites were typed into AA,AG and GG genotypes,and gene distribution met Hardy-Weinberg equilibrium (P ＞ 0.05).The frequencies of genotypes AA,AG and GG in Tibetans were 55.8％ (172/308),37.3％ (115/308) and 6.8％ (21/308),respectively;the frequencies of the three genotypes in Kazakhs were 69.7％ (202/290),27.6％ (80/290) and 2.8％ (8/290),respectively;the frequencies of the three genotypes in Mongolians were 60.5％ (158/261),36.0％ (94/261) and 3.4％ (9/261),respectively;the frequencies of the three genotypes in Han people were 60.9％ (259/425),33.6％ (143/ 425) and 5.4％ (23/425),respectively;the frequencies of genotypes in Russians were 72.3％ (94/130),26.9％ (35/130) and 0.8％ (1/130),respectively;the differences of the three genotype frequencies between different ethnic groups were statistically significant (x2 =24.757,P ＜ 0.05).The skeletal fluorosis detection rates in different ethnic from high to low were Tibetans (39.94％,123/308),Kazakhs (33.79％,98/290),Mongolians (22.22％,58/261),Han people (13.41％,57/425) and Russians (8.46％,11/130),and the differences were statistically significant (x2 =100.156,P＜ 0.05).Skeletal fluorosis detection rates of different genotypes were AA (24.18％,214/885),AG/GG (25.14％,133/529),the difference was not statistically significant between the groups (x2 =0.165,P ＞ 0.05).After the ethnic stratification,the differences were also not statistically significant (P ＞ 0.05).Only in the group of Tibetans whose urine fluoride level was 1.6-3.2 mg/L and Mongolians under age 45 were found that the G gene was one of the risk factors in skeletal fluorosis [OR =2.035,95％ CI (1.003-4.128);OR =5.602,95％CI (1.461-21.479)];G gene might be a protective factor in the Mongolians aged 45 years and over [OR =0.422,95％CI(0.190-0.938)].Conclusion This study does not find a positive correlation between CYP1A1 gene polymorphism and the ethnic differences to bricktea fluorosis.