Association between polymorphism in the promoter region (G/C-915) of PAX9 gene and third molar agenesis

Role of polymorphisms of MSX1 and PAX9 genes in palatal impaction of maxillary canines

OBJECTIVE

Maxillary canines are the second-most commonly impacted teeth. About two-thirds of the impacted maxillary canines are palatally impacted. Studies in the past have shown that 40% of cases with palatal impaction of maxillary canines presented with agenesis of third molars. Sporadic agenesis of third molars have been associated with polymorphisms in the MSX1 and PAX9 genes. The present study aims at evaluating the association between polymorphisms of PAX9, MSX1 and palatally impacted canines in a random population sample.

DESIGN AND SETTING

Fifty individuals with palatally impacted maxillary canines and 50 gender and age-matched controls were included in this study.

METHODS

Single nucleotide polymorphisms (SNPs), rs12532 of MSX1 and rs2073247 of PAX9, were genotyped using polymerase chain reaction and restriction fragment length polymorphism. The significance of the differences among the groups was assessed by odds ratio and Chi-squared test with a 95% confidence interval.

RESULTS

Single nucleotide polymorphisms rs12532 [MSX1] and rs 2073247 [PAX9] showed a statistically significant association with palatal impaction of maxillary canines. In addition, the combined presence of the AG/CT genotypes of these genes in an individual caused a significant increase in the risk for palatal impaction.

CONCLUSION

These results suggest that the rs12532 and rs2073247 polymorphisms of genes MSX1 and PAX9 are positively associated with palatal impaction of maxillary canines. Future studies investigating various other SNPs of these genes in a larger sample of different populations could provide clinching details.

The role of PAX9 promoter gene polymorphisms in causing hypodontia: a study in the Jordanian population

Background

The congenital absence of one or few teeth, hypodontia, is considered one of the utmost dental ageneses in human beings. Several genes have been shown to be involved in the development of hypodontia such as paired box gene 9 (PAX9). The expression of PAX9 is controlled by several polymorphic elements in the promoter region of the gene on 14q13.3 locus. The aim of this study was to find any association between PAX9 c.-912T>C (rs2073247) and c.-1031G>A (rs2073244) promoter polymorphisms and the development of hypodontia among the Jordanian population.

Methods

Genotyping of the polymorphisms in 72 unrelated subjects with hypodontia was performed using PCR-restriction fragment length polymorphism (RFLP) technique and compared with that of 72 normal healthy unrelated control individuals.

Results

The hypodontia group had a significantly higher -1031GG genotype (P<0.01) and a significantly lower -912TC genotype (P<0.01) compared with the control group. The results suggest that the transcriptional activity of PAX9 gene is affected by polymorphisms in the promoter region of this gene and is associated with hypodontia phenotype.

Conclusion

The rs2073247) and rs2073244 promoter polymorphisms of PAX9 might play a role in the development of hypodontia in the Jordanian population.

Prevalence of Third Molar Agenesis: Associated Dental Anomalies in Non-Syndromic 5923 Patients

The aim of this study was to investigate the prevalence of third molar agenesis and other associated dental anomalies in Bangladeshi population and to investigate the relationship of other dental anomalies with the third molar presence/agenesis. A retrospective study was performed using panoramic radiographs of 5923 patients, who ranged in age from 10 to 50 years. All radiographs were analyzed by Planmeca Romexis® 3.0 software (Planmeca Oy, Helsinki, Finland). Pearson chi-square and one way ANOVA (Post Hoc) test were conducted. The prevalence of third molar agenesis was 38.4%. The frequency of third molar agenesis was significantly higher in females than males (p <0.025). Third molar agenesis was significantly more prevalent in maxilla as compared to mandible (p <0.007). The prevalence of other dental anomalies was 6.5%, among them hypodontia was 3.1%. Prevalence of third molar agenesis varies in different geographic region. Among the other dental anomalies hypodontia was more prevalent.

Prevalence of maxillary lateral incisor agenesis and associated skeletal characteristics in an orthodontic patient population

OBJECTIVES

This study was aimed to investigate the prevalence of maxillary lateral incisor agenesis and associated skeletal characteristics in an orthodontic patient population.

MATERIALS AND METHODS

The records of the 1066 patients seeking orthodontic treatment were screened for maxillary lateral incisor agenesis (MLIA). The following data were recorded for each subject: age; gender; unilateral or bilateral agenesis of MLI and side. The lateral cephalogram of each subject with MLIA was digitally traced. The data were compared to age-matched control orthodontic patients with skeletal Class I.

RESULTS

The prevalence of maxillary lateral incisor agenesis was 4.9% (52 patients) in which 63.5% were females. There was a significant difference between MLIA patients and controls in sagittal relationships (ANB, Wits, AB plane, angle of convexity and Co-A/Co-Gn differential analyses) p < 0.05.

CONCLUSIONS

Patients with maxillary lateral incisor agenesis showed a significant tendency for skeletal Class III compared with the Class I control. This could be attributed to maxillary hypoplasia/retrognathia.

Complex analysis of multiple single nucleotide polymorphisms as putative risk factors of tooth agenesis in the Hungarian population

OBJECTIVES

The role was studied of multiple single nucleotide polymorphisms in tooth agenesis in the Hungarian population using a complex approach.

METHODS

Eight SNPs, PAX9 -912 C/T, PAX9 -1031 A/G, MSX1 3755 A/G, FGFR1 T/C rs881301, IRF6 T/C rs764093, AXIN2-8150 A/G, AXIN2-8434 A/G and AXIN2-30224 C/T, were studied in 192 hypodontia and 17 oligodontia cases and in 260 healthy volunteers. Case-control analysis was performed to test both allelic and genotypic associations as well as associations at the level of haplotypes. Multivariate exploratory Bayesian network-based multi-level analysis of relevance (BN-BMLA) as well as logistic regression analysis were performed.

RESULTS

Conventional statistics showed that PAX9 SNP -912 C/T and the MSX1 SNP changed the incidence of hypodontia, although after Bonferroni correction for multiple hypothesis testing, the effects were only borderline tendencies. Using a statistical analysis better suited for handling multiple hypotheses, the BN-BMLA, PAX9 SNPs clearly showed a synergistic effect. This was confirmed by other multivariate analyses and it remained significant after corrections for multiple hypothesis testing (p < 0.0025). The PAX9-1031-A-PAX9-912-T haplotype was the most relevant combination causing hypodontia. Interaction was weaker between PAX9 and MSX1, while other SNPs had no joint effect on hypodontia.

CONCLUSION

This complex analysis shows the important role of PAX9 and MSX1 SNPs and of their interactions in tooth agenesis, while IRF6, FGFR1 and AXIN2 SNPs had no detectable role in the Hungarian population. These results also reveal that risk factors in hypodontia need to be identified in various populations, since there is considerable variability among them.

PAX9 polymorphisms and susceptibility with sporadic tooth agenesis in Turkish populations: a case-control study

Background

Hypodontia, the congenital absence of one or a few teeth is one of the most common alterations of the human dentition. Familial hypodontia is caused by mutations in PAX9, Msx1 and Axin2 genes. Limited numbers of studies are present to show etiological factors beyond this anomaly in Turkish community belonging to Caucasian racial family. The purpose of this study is to investigate the relationships between the two different single nucleotide polymorphisms that are G-1031A and T-912C with hypodontia in Caucasians.

200 individuals having hypodontia and 114 normal individuals having all 32 teeth present were selected for the study. Blood samples were collected from each individual and DNA was extracted. To determine the polymorphisms, PCR-RFLP method was used.

Results

The outcomes suggest that the individuals having AC haplotype carry less risk in having hypodontia compared with the rest of the haplotype groups (OR = 3.88; CI = 95%; p = 0.001). The ratio of GT haplotype is less in the hypodontia group meaning that the GT carriers are in risk group in terms of hypodontia risk.

Conclusion

These results indicate that polymorphisms in the promoter region of PAX9 gene may have an influence on the transcriptional factors and activity of this gene and are associated with hypodontia in Caucasian individuals.

Associations between the risk of tooth agenesis and single-nucleotide polymorphisms of MSX1 and PAX9 genes in nonsyndromic cleft patients

OBJECTIVE

To investigate the association between the risk of tooth agenesis and single-nucleotide polymorphisms (SNPs) of MSX1 and PAX9 genes in nonsyndromic cleft patients.

MATERIALS AND METHODS

The subjects were 126 Korean nonsyndromic cleft patients. Tooth agenesis type (TAT) was classified as none (0); cleft area (1); cleft area + other area (2); and other area (3) based on agenesis of the maxillary lateral incisor (MXLI) and another tooth within or outside the cleft area. TAT was further grouped into two subcategories (0 and 1) and four subcategories (0, 1, 2, and 3). Three SNPs of MSX1 and 10 SNPs of PAX9 were investigated using Fisher's exact test and logistic regression analysis.

RESULTS

Although the association between genotype distribution of PAX9-rs7142363 and TAT was significant (P < .05 in four subcategories), genotypic odds ratios (GORs) of SNPs in each TAT were not meaningful. However, for MSX1-rs12532 and PAX9-rs2073247, associations between genotypic distribution and TAT were significant (P < .01 in four subcategories and P < .05 in two subcategories; P < .01 in two subcategories, respectively). In cleft area, GORs of MXLI agenesis in genotypes GA of MSX1-rs12532 and CT of PAX9-rs2073247 were increased by 3.14-fold and 4.15-fold compared with genotype GG of MSX1-rs12532 and CC of PAX9-rs2073247, respectively (P <. 01; P < .05). In cleft area + other area, the GOR of agenesis of MXLI and another tooth in genotype AA of MSX1-rs12532 was increased by fivefold compared with genotype GG (P < .05).

CONCLUSION

Genetic disturbances of MSX1 and PAX9 genes are associated with tooth agenesis within and outside the cleft area.

Contrasting evolutionary dynamics of the developmental regulator PAX9, among bats, with evidence for a novel post-transcriptional regulatory mechanism

Morphological evolution can be the result of natural selection favoring modification of developmental signaling pathways. However, little is known about the genetic basis of such phenotypic diversity. Understanding these mechanisms is difficult for numerous reasons, yet studies in model organisms often provide clues about the major developmental pathways involved. The paired-domain gene, PAX9, is known to be a key regulator of development, particularly of the face and teeth. In this study, using a comparative genetics approach, we investigate PAX9 molecular evolution among mammals, focusing on craniofacially diversified (Phyllostomidae) and conserved (Vespertilionidae) bat families, and extend our comparison to other orders of mammal. Open-reading frame analysis disclosed signatures of selection, in which a small percentage of residues vary, and lineages acquire different combinations of variation through recurrent substitution and lineage specific changes. A few instances of convergence for specific residues were observed between morphologically convergent bat lineages. Bioinformatic analysis for unknown PAX9 regulatory motifs indicated a novel post-transcriptional regulatory mechanism involving a Musashi protein. This regulation was assessed through fluorescent reporter assays and gene knockdowns. Results are compatible with the hypothesis that the number of Musashi binding-elements in PAX9 mRNA proportionally regulates protein translation rate. Although a connection between morphology and binding element frequency was not apparent, results indicate this regulation would vary among craniofacially divergent bat species, but be static among conserved species. Under this model, Musashi's regulatory control of alternative human PAX9 isoforms would also vary. The presence of Musashi-binding elements within PAX9 of all mammals examined, chicken, zebrafish, and the fly homolog of PAX9, indicates this regulatory mechanism is ancient, originating basal to much of the animal phylogeny.