[Association between ameloblastin gene polymorphisms and the susceptibility to dental fluorosis]

To study the distribution of ameloblastin (AMBN) gene polymorphism in coal-fire caused fluorosis (CFCF) in Chongqing municipality and the relationship between AMBN gene polymorphism and the susceptibility to dental fluorosis.Under a case-control study, 100 children aged 8 - 12 and 30 adults with dental fluorosis were enrolled in Wushan and Fengjie counties of Chongqing from December 2010 to February 2011. Another 100 children aged 8 - 12 and 30 adults with non-dental fluorosis were chosen as internal control groups together with 50 children and 30 adults without dental fluorosis were selected as external control groups in the non-epidemic area of Yubei district. DNA was extracted from peripheral blood sample of these people. Genotype of AMBN gene 7 extron 538_540delGGA, 10 extron 657AG and 13 extron 986CT loci were detected using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique.The rates of 7 extron 538_540delGGA loci among case, internal and external control groups were as follows: GGA/GGA-/- 61.2% (74/121), 78.5% (102/130), 74.3% (52/70) ; GGA/-: 24.0% (29/121), 15.4% (20/130), 22.9% (16/70) ; -/-: 14.8% (18/121), 6.1% (8/130), 2.8% (2/70), the difference was statistically significant (χ(2) = 14.353 P0.05). The AA appeared to be 86.8% (105/121), 93.1% (121/130), 91.4% (64/70) and AG were 13.2% (16/121), 6.9% (9/130), 8.6% (6/70), with difference not statistically significant (χ(2) = 2.972, P0.05). CC appeared as 81.0% (98/121), 90.0% (117/130), 87.1% (61/70) while CT as 19.0% (23/121), 10.0% (13/130), 12.9% (9/70), with difference not statistically significant (χ(2) = 4.319, P0.05). In comparing with the two control groups, the frequency of GGA/GGA was decreasing (χ(2) values were 8.957, 3.405, respectively, P0.05) while the frequency of -/- was increasing (χ(2) values were 5.134, 6.833, respectively, P0.05).from the univariate analysis showed that the individuals who were carrying -/- genotype had an increased risk of suffering from fluorosis (OR values were 2.7, 5.9, respectively, P0.05). When compared with the internal control group, the CT genotype of case group showed an increase (χ(2) = 4.139, P0.05) while individuals that carrying CT genotype had an increased risk of suffering from fluorosis (OR = 2.1, P0.05), in epidemic-area.Our results showed that the 7 extron 538_540delGGA and the 13 extron 986CT loci polymorphism in AMBN gene might serve as the susceptibility factors causing the coal-fired fluorosis.