Title

PAX9 GENE POLYMORPHISMS AND MISSING TEETH

Lead Author Affiliation

Dugoni School of Dentistry

Second Author Affiliation

Dugoni School of Dentistry

Third Author Affiliation

Dugoni School of Dentistry

Fourth Author Affiliation

Dugoni School of Dentistry

Fifth Author Affiliation

Dugoni School of Dentistry

Introduction

It was shown in both mouse and human tooth development that PAX9 and MSX1 are the most important genes regulating progression through early stages of tooth development. These genes are encoding transcription factors involved in epithelial/mesenchymal interactions. Their key function seems to be maintenance and regulation of Bmp4 expression in dental mesenchyme. If the functions of PAX9 and MSX1 are disturbed, the tooth will not develop.

Purpose

To study one mutation in Exon1 and seven mutations in Exon2 of PAX9 gene in the sample of individuals with missing teeth (probands) and their parents and siblings. Probands as well as their respective family members were classified by the type of missing teeth and family history of hypodontia.

Method

Our sample consisted of 43 individuals with congenitally missing teeth; 21 were dental student volunteers and 22 were patients from orthodontic clinic. Altogether, 82 saliva specimens were collected from cases and their immediate family members. Majority of specimens were collected using our own protocol: participants were asked to rinse their mouth with 0.5 oz of Listerine® for 30 seconds followed by a rinse with water for 30 seconds in order to get rid of food particles. They were then asked to spit into a 50 mL Falcon tube until 3-5 mL of saliva was collected. The Falcon tubes were transferred to the Craniofacial genetics laboratory where drops of saliva were spotted on filter paper and allowed to dry. Modified Chelex method was used to extract DNA. A smaller number of specimens were collected using Oragene saliva kit. Following DNA isolation, PCR was done using specific primers for each polymorphism, agarose electrophoresis followed to confirm PCR product, which was then purified and sent to sequencing laboratory. The sequenced specimens were analyzed for PAX9 genotypes.

Results

Out of forty genetically examined individuals with hypodontia, nine were positive for some of the PAX9 polymorphisms. All nine were heterozygotes. Seven individuals had a PAX9 mutation in the DNA-binding region. The numbers are not definitive, because the study is still in progress.

Significance

Results of this pilot study indicate a rather strong genetic component associated with PAX9 gene mutations in individuals with hypodontia. Evaluation of a larger sample will enable us to draw more definitive conclusions regarding the inheritance of hypodontia related to PAX9 gene mutations.

Location

DeRosa University Center, Stockton campus, University of the Pacific

Format

Poster Presentation

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Mar 25th, 10:00 AM Mar 25th, 3:00 PM

PAX9 GENE POLYMORPHISMS AND MISSING TEETH

DeRosa University Center, Stockton campus, University of the Pacific

It was shown in both mouse and human tooth development that PAX9 and MSX1 are the most important genes regulating progression through early stages of tooth development. These genes are encoding transcription factors involved in epithelial/mesenchymal interactions. Their key function seems to be maintenance and regulation of Bmp4 expression in dental mesenchyme. If the functions of PAX9 and MSX1 are disturbed, the tooth will not develop.