Genetic study of the AMELX gene mutation on dental malformations of patients with and without cleft lip and palate.

Author(s)

Fernanda Veronese de Oliveira

• Document type: Master's Dissertation
• Press: Bauru.
• Institution: Universidade de São Paulo (USP). Faculdade de Odontologia de Bauru (FOB/SDB)
• Defense date: 2011-12-16

Examining board members

Thais Marchini de Oliveira Valarelli; Maria Aparecida de Andrade Moreira Machado; Carlos Ferreira dos Santos

• Advisor: Thais Marchini de Oliveira Valarelli

Abstract

The aim of this study was to investigate the occurrence of mutations in the AMELX candidate gene involved in enamel formation, in patients with and without cleft lip and palate and dental malformation. For gene analysis proposed was collected saliva from 165 patients who were divided in 4 groups: Group 1 - 46 individuals with cleft lip and palate and dental malformation, Group 2 - 34 individuals with cleft lip and palate without dental malformations; Group 3 - 34 individuals without cleft lip and palate with dental malformations and Group 4 - 51 individuals without cleft lip and palate and dental malformation. Next, genomic DNA was extracted from this saliva, followed by PCR and direct DNA sequencing. All samples with mutations were sequenced twice; once using the forward primer and a second time using the reverse primer. After data analysis with Software SeqScape® 2.6, the data were collated. Of the 165 samples, 95%, 90%, 89%, 88%, 94% and 100% of the samples were successfully sequenced from exons 2, 3, 4, 5, 6 and 7 respectively. Overall, of the 990 total sequenced exons (six exons in 165 samples of saliva), 918 exons (93%) were able to be completely sequenced and analyzed. Mutations were detected in 37 of the fragments (4%), more specifically, 14 in Group 1 (1.5%), 12 in Group 2 (1.3%), four in Group 3 (0.4%) and seven in Group 4 (0.7%), which included only missense and silent mutations, distributed throughout exons 2, 6 and 7 in the AMELX gene in eight different locations on chromosome X. According to the results obtained from direct sequencing of protein-coding exons of the AMELX gene, mutations were found in the nucleotide sequence of the AMELX gene in individuals with and without cleft lip and palate and dental malformation. It was also observed that the mutation in position 75 of exon 6 was present in all groups, suggesting that, though a silent mutation, may be a new polymorphism to be cataloged: it was found in 26 patients, the total of 165, representing 16%. However, this study cannot confirm that these mutations directly altered the phenotypes of the patients in the groups tested. (AU)

• FAPESP's process: 09/12289-0 - Genetic study of AMELX and ENAM gene mutations on dental malformations of patients with and without cleft lip and palate
• Grantee: Fernanda Veronese de Oliveira
• Support Opportunities: Scholarships in Brazil - Master