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 (DpH) 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 (k ¼ 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 w 2 , Student's, and Mann-Whitney tests (a ¼ 0.05). The PI and DpH of the upper and lower teeth were significantly higher in the carious group than control (Po0.05). 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 (P40.05). 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 ¼ 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.

Genetic polymorphisms in the carbonic anhydrase VI gene and dental caries susceptibility

“…In 2009, Yarat et al (2009) reported that these studies found no differences in the frequency of the SNPs [rs2274327 (C/T), rs2274328 (A/C)], salivary pH, and buffering capacity among Turkish dental students with caries and those who were caries-free. However, a later study including 245 children investigated the same 2 SNPs and reported that 1 SNP [rs2274327 (C/T)] was associated with a decrease in salivary buffering capacity in healthy children, but that the gene polymorphisms were not directly related to caries (Peres et al, 2010). Recently, 4 SNPs [rs2274327(C/T), rs2274328 (A/C), rs2274329 (G/C), and rs2274330 (G/C)] were studied in 43 subjects, and no correlation was found between SNPs in CA VI exon 2 and salivary buffering capacity or pH; however, a positive significant correlation was found between salivary CA activity and the frequency of SNPs in exon 2 of CA VI in diabetic groups (Koç et al, 2012).…”

“…Moreover, CA VI binds to the enamel pellicle and retains its enzymatic activity on the tooth surface, which may catalyze the conversion of salivary bicarbonate and microbe-delivered hydrogen ions to carbon dioxide and water (Leinonen et al, 1999;Kimoto et al, 2006). It was recently reported that a C/T polymorphism in CA VI may be associated with salivary buffer capacity (Peres et al, 2010). These data suggested that salivary CA VI plays an important role in protecting the teeth from caries.…”

“…Previous studies (Peres et al, 2010;Padiglia et al, 2010;Koç et al, 2012) examining CA VI gene polymorphisms mainly focused on exon 2 or 3, as these polymorphisms result in changes in the amino acid sequence in the secreted protein and may interfere with enzyme function. However, the introns may be involved in the regulation of gene expression, but no studies have examined the relationship between polymorphisms in the intron regions of the CA VI gene and caries susceptibility.…”

Salivary Carbonic Anhydrase Vi, Zinc Sulfate Taste Acuity and Frequency of Illness: A Pilot Study

“…Additionally, the study did not account for certain variables which have been demonstrated to effect levels of CA6. For example, polymorphisms of CA6 have been associated with both alterations in taste function and the amount of CA6 produced (Peres et al, 2010;Aidar et al, 2013). Also, when salivary flow rate slows, such as in the case of acute hyperglycemia, CA6 levels decrease (Negrato and Tarzia, 2010).…”

Salivary Proteins and Effects on Dental Caries: Review

“…CA VI enzimi minenin hidroksiapatit kristallerine adsorbe olabilir, pelikıl ve dental biyofilm içerisinde varlığını sürdürebilir. 14,47 Sonuç olarak, tükürük CA VI enzimi oral fizyoloji için anahtar enzim olup, bu enzim ile ilgili çalışmalar devam etmektedir.…”