Epidemiological Survey Of Dental Fluorosis And Its Relationship With The CFTR Gene Polymorphism Study

Endemic fluorosis is an environmental-geochemical endemic disease which does damage to human skeleton and teeth. It is caused by a long-term living in the high fluoride environment and the inhalation of polluted air or intake of food or water polluted by fluoride. As a result, it turns out to be a state of chronic systematic poisoning. Some areas of Shaanxi province are located in high fluoride content region. Our research group conducted an epidemiological survey of fluorosis in Ankang area of Shaanxi Province. We focused on the fluorine content of the drinking water and clinical features and incidence of dental fluorosis. We looked for the genetic factors which have individual differences when connected with high fluorine and analyzed the connection between the polymorphism of chloride channel gene and fluoride sensitivity. We chose the chloride channel gene as the sensitive gene and tried to interpret the endemic fluorosis in a new genetic aspect.We conducted dental fluorosis epidemiological investigation in Haoping and Liushui of Ankang area by questionnaire and clinical examination and performed statistical analysis of the local prevalence. Then we obtained the genomic DNA of the clients and selected the cystic fibrosis transmembrane conductance regulator (CFTR) as the targeted gene to detect the corresponding polymorphic loci. Finally, we conducted bioinformatics analysis and comparison of the polymorphism results.1. We selected young people aged 10-22 years old into the survey randomly in the schools of Haoping and Liushui, and recorded the clients'age, height, weight, residence and other general information by questionnaire. The clients were examined and diagnosed based on the Dean Clinic Diagnostic Standard for Dental Fluorosis. We extracted Genomic DNAs from the whole blood of the clients and detected the fluoride content of samples from the major sources of drinking water. Finally we analyzed the clinical examination results and work out the incidence of dental fluorosis.2. We examined the fluoride concentration of local drinking water based on Water quality–Determination of fluoride Visual colorimetry with zirconium alizarinsulfonate.3. The genomic DNAs were extracted from whole blood for polymerase chain reaction (PCR) amplification. Testing single nucleotide polymorphisms (SNP) M470V of the CFTR gene by restriction enzyme digestion and ligase chain reaction (LCR) to determine the genotyping and perform analysis of the data by statistics.4. We tested the CFTR gene single nucleotide polymorphisms (SNP) TG-repeat and Poly-T by DNA sequencing to determine the genotyping and analyze the data by statistics. The results of the three SNPs were genotyped comprehensively, and we compared the distribution of the genotype between dental fluorosis patients and normal control group. Also we compared the genotype distribution of the different severity of dental fluorosis and in the different geographical conditions. We participate to find the correlation between CFTR gene polymorphism and dental fluorosis.The main results are as follows:1. The candidates who were obtained the complete information and whole blood are 720, and the local rensidents are 681. Among the objects in the two places, 628(92.22%) cases were diagnosed as dental fluorosis.2. The fluoride concentration of drinking water in Haoping and Liushui was 0.38mg/L and 0.98mg/L respectively, which were both lower than the national standard (≤1.0 mg/L).3. The three kinds of genotype were MV(78.54%),VV(18.63%) and MM(2.83%). The V470 was the major haplotype.4.The four types of Poly-T Polymorphic loci were T5/T7,T7/T7,T7/T9,T9/T9, of which T7/T9 was the major genotype and T7 was the major haplotype.5. After comprehensive study of the genotype and the pathological changes, the common genotypes were MV7-11/7-11, MV7-11/9-10 and VV7-11/9-10.We draw the following conclusions:1. In Haoping and Liushui, as the age increase, the the incidence was higher and the prevalence was more severe.2. The fluoride concentrations of drinking water in Haoping and Liushui were both lower than the national standard.3. There is a certain correlation between the low MM polymorphism and the high incidence of dental fluorosis.4. The high MV7-11/7-11 genotype distribution had a correlation with the severity of dental fluorosis.Our research mainly focused the molecular survey on the traditional environmental-geochemical endemic disease, dental fluorosis. For the first time, we detected the genetic background of dental fluorosis from the view of chloride channels. We found the CFTR gene polymorphisms were closely related with dental fluorosis. Our results may contribute to the new explanations of molecular mechinsms of dental fluorosis and provide the basic theory to the preventation and cure of dental fluorosis.