Triagem de mutação no éxon 3 do gene IRF6 em indivíduos com fissura labiopalatina e agenesia dentária: padronização de protocolo para seqüenciamento de DNA genômico a partir de saliva / Screening of mutation in IRF6 gene of subjects with cleft lip and palate and tooth agenesis: protocol standardization for sequencing of genomic DNA extracted from saliva

AUTOR(ES)
DATA DE PUBLICAÇÃO

2009

RESUMO

Cleft lip and palate and tooth agenesis are considered changes in embryonic development. These phenotypes occur as a result of the interaction of genetic and environmental factors, suggesting a multifactorial inheritance pattern. Among the candidate genes for these phenotypes IRF6 appears as one of the most important. Direct sequencing, among other techniques, can be used to perform such genetic studies. The aim of this study was to standardize a protocol for direct sequencing of genomic DNA extracted from whole saliva to allow further search of mutations or polymorphisms in exon 3 of IRF6 gene in individuals with nonsyndromic cleft lip and palate and tooth agenesis. Volunteers were 120 subjects divided into four groups: Group 1 - 30 individuals with tooth agenesis and cleft, Group 2 - 30 individuals with cleft only, Group 3 - 30 individuals with tooth agenesis only, and Group 4 - Control. For the analysis of the exon 3 of IRF6 gene, saliva was collected to test three protocols for the extraction of genomic DNA. Additionally, during the protocol standardization for direct sequencing, different methodologies for the other three steps of sample preparation were evaluated: purification of PCR product, optimization of the use of BigDye® v3.1 Terminator, and purification of the sequencing product. The samples were sequenced on ABI 3130XL Genetic Analyzer, and the results were analyzed using specific softwares. Heterozygous and homozygous variations in the sequences of the exon 3 of IRF6 gene of each individual were searched in the electropherograms. The results showed that the protocol for DNA extraction from saliva using InstageneTM Matrix associated with proteinase K and 1% sodium dodecyl sulfate showed the best results in the quantity and quality of the extracted DNA. As far as the purification of the PCR product, the method of choice was the purification in specific columns. BigDye® v3.1 was used with success in a volume 2 L per reaction, and the purification of the sequencing product with X-Terminator showed the best results. For the mutation screening, only one individual of the control group presented sequence variation of the heterozygous type. It was concluded that it is possible to successfully perform, on the ABI 3130XL platform, the direct sequencing of genomic DNA extracted from whole saliva using the protocols standardized in this work. It was also concluded that in the group analyzed, no association between the exon 3 of IRF6 gene and the phenotypes of nonsyndromic cleft lip and palate and tooth agenesis was found.

ASSUNTO(S)

cleft lip fenda labial fissura palatina anodontia molecular biology genetics genética cleft palate biologia molecular anodontia

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