Screening of mutations and polymorphisms of candidate genes to dental malformation in patients with cleft lip and palate

Author(s)

Fernanda Veronese de Oliveira

• Document type: Doctoral Thesis
• Press: Bauru.
• Institution: Universidade de São Paulo (USP). Faculdade de Odontologia de Bauru (FOB/SDB)
• Defense date: 2015-06-10

Examining board members

Thais Marchini de Oliveira Valarelli; Gisele da Silva Dalben; Maria Beatriz Duarte Gavião; Daniela Rios Honório; Carlos Ferreira dos Santos

• Advisor: Thais Marchini de Oliveira Valarelli

Abstract

The purpose of this study was to investigate the occurrence of mutations and polymorphisms (SNPs) in candidate genes to defects in the formation of enamel in individuals with cleft lip and palate (CLP) unilateral or bilateral incisive transforame isolated and associate genotype-phenotype of individuals with CLP and dental malformation (DM) in permanent teeth maxillary central incisors. For analysis of the proposed genes, saliva samples from 165 individuals from 6 to 15 years old, of both genders, were collected and divided into 4 groups: Group 1 - 46 individuals with CLP and DM; Group 2 - 34 individuals with CLP and without DM; Group 3 - 34 subjects without CLP and DM; Group 4 - 51 subjects without CLP and DM. Extraction of genomic DNA from saliva samples was performed, followed by Polymerase Chain Reaction, direct sequencing of 2, 3, 4, 5, 6 and 7 exons of AMELX gene and genotyping of SNPs rs3796703, rs3796704, rs3796705, rs7671281, rs2609428 and rs35951442 in the ENAM gene. For statistical analysis we used the Fisher\'s exact test and Pearson\'s chi-square test. Regarding direct sequencing of AMELX gene, mutations were found in 30.4% (n=14), 35.3% (n=12), 11.8% (n=4) and 13.7% (n=7) of individuals in Groups 1, 2, 3 and 4, respectively. Thirty-seven mutations were detected and distributed over the exons 2 (1 mutation - 2.7%), 6 (30 mutations - 81.08%) and 7 (6 mutations - 16.22%) of AMELX gene. There was a significant increase (p=0.003) in the frequency of mutations in individuals with CLP (Groups 1 and 2 - 65.7%) compared to subjects without CLP (Groups 3 and 4 - 25.5%). Regarding the 30 mutations found in exon 6, 43.34% (n=13), 23.33% (n=7), 13.33% (n=4) and 20% (n=6) were found in Groups 1, 2, 3 and 4, respectively. The c.261C>T silent mutation (rs2106416) was detected in 26 individuals distributed in all groups studied, and was significantly more found (p=0.003) in the groups with CLP (23.75%) compared to the groups without CLP (8.23%). In groups without DM (Groups 2 and 4), this polymorphism was also significantly more found (p=0.032) among individuals with CLP (Group 2 - 17.65%) compared to those without CLP (Group 4 - 7.8%). Regarding the SNPs genotyping in ENAM gene, the prevalence of heterozygous in SNP rs2609428 was higher (p=0.006) in individuals without CLP with DM (Group 3 - 19.2%) than in individuals with CLP and DM (Group 1 - 0%), as well as the prevalence of the heterozygous/homozygous mutated in individuals without CLP (10%) was higher (p=0.028) than in individuals with CLP (1.3%). No statistically significant difference was found in the other SNPs analysed in the ENAM gene. Based on the obtained results, it is suggested that the AMELX gene may be considered a candidate gene for the CLP. The SNP rs2106416 in AMELX gene may be considered a marker for CLP and the SNP rs2609428 in ENAM gene may be associated with DM in the absence of CLP. (AU)

• FAPESP's process: 11/21190-7 - Screening for mutations and polymorphisms of candidate genes on dental malformations of patients with cleft lip and palate
• Grantee: Fernanda Veronese de Oliveira
• Support Opportunities: Scholarships in Brazil - Doctorate