title: Association of polymorphisms in the carbonic anhydrase 6 gene with salivary buffer capacity, dental plaque pH, and caries index in children aged 7-9 years.
abstract: Carbonic anhydrase VI is a secreted enzyme that catalyzes the hydration of carbon hydroxide in saliva and other body fluids. This enzyme has been implicated in taste and gastrointestinal dysfunctions, tooth erosion, and caries. The purpose of this study was to analyze the allele and genotype distribution of three polymorphisms in the coding sequences of (CA6) gene and check for possible associations with salivary buffer capacity, number of decayed, missing, and filled teeth in deciduous and permanent teeth (dmft/DMFT, Decayed/Missing/Filled Teeth), plaque index (PI), and the plaque pH variation (DeltapH) in children aged 7-9 years. Two hundred and forty-five children from both genders, residents in area with fluoridated water (Piracicaba, São Paulo, Brazil) were divided into two groups: caries free and with caries. The clinical examinations were conducted by a single previously calibrated examiner (kappa=0.91) in an outdoor setting using a mirror and a probe, according to WHO criteria index (dmft/DMFT). Approximately 2 h after the first daily meal, the buffer capacity (BC) and the plaque pH were analyzed by means of a pH meter and an ion selective electrode. Plaque pH was measured immediately and 5 min after a mouth rinse with a 10% sucrose solution. The data were submitted to chi(2), Student's, and Mann-Whitney tests (alpha=0.05). The PI and DeltapH of the upper and lower teeth were significantly higher in the carious group than control (P<0.05). There was no difference between the groups in relation to BC. There was no association between the alleles and genotypes distributions for polymorphisms in the CA6 gene exons 2 and 3 and caries experience (P>0.05). There was a positive association between buffer capacity and the rs2274327 (C/T) polymorphism. The allele T and genotype TT were significantly less frequent in individuals with the highest buffer capacity (P=0.023 and 0.045, respectively). This finding encourages future studies relating CA6 gene polymorphisms and their association with malfunctions, such as taste and gastrointestinal alterations, or the differential effect of chemical modulators on the protein products originated from the distinct genotypes of the CA6 gene.
authors.affiliation: Department of Pediatric Dentistry, Piracicaba Dental School, University of Campinas-Unicamp, Sao Paulo, Brazil. rochaperes@fop.unicamp.br
authors.forename: R C R
authors.initials: RC
authors.lastname: Peres
authors.forename: G
authors.initials: G
authors.lastname: Camargo
authors.forename: L S
authors.initials: LS
authors.lastname: Mofatto
authors.forename: K L
authors.initials: KL
authors.lastname: Cortellazzi
authors.forename: M C L G
authors.initials: MC
authors.lastname: Santos
authors.forename: M
authors.initials: M
authors.lastname: Nobre-dos-Santos
authors.forename: M N
authors.initials: MN
authors.lastname: Santos
authors.forename: C C
authors.initials: CC
authors.lastname: Bergamaschi
authors.forename: S R P
authors.initials: SR
authors.lastname: Line
mesh_terms: D000595:Amino Acid Sequence; D002021:Buffers; D002256:Carbonic Anhydrases / Q000235:genetics*; D002648:Child; D004245:DMF Index; D003731:Dental Caries / Q000235:genetics* / Q000378:metabolism; D003773:Dental Plaque / Q000235:genetics* / Q000378:metabolism; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008297:Male; D008969:Molecular Sequence Data; D020641:Polymorphism, Single Nucleotide; D012463:Saliva / Q000502:physiology
chemical_list: D002021:Buffers; D002256:Carbonic Anhydrases; C477051:carbonic anhydrase VI