Association between facial measurements and polymorphisms in human epidermal growth factor and transforming growth factor β1

New insights into the genetics of mandibular retrognathism: novel candidate genes

PURPOSE

Mandibular retrognathism (MR) is a common skeletal malocclusion in humans with a strong genetic component. Single nucleotide polymorphisms (SNPs) in genes encoding epidermal growth factor (EGF) and EGF receptor (EGFR) could be involved in the etiology of mandibular retrognathism. Therefore, in this study, we investigated whether SNPs in the genes encoding for EGF and EGFR are associated with MR in German teenagers.

METHODS

This nested case-control study evaluated German orthodontic patients, aged 10-18 years. DNA, which was isolated from buccal epithelial cells using two cytobrushes, was used for genotyping analysis and digital pretreatment lateral cephalograms were examined to calculate SNB and ANB. Patients with a retrognathic mandible (SNB < 78°) were included as cases, while patients with an orthognathic mandible (SNB = 78-82°) were included as controls. Four SNPs in the genes encoding for EGF and EGFR were chosen and genotyped using real-time PCR. Allele, genotype, and haplotype frequency were compared across groups (α = 5%).

RESULTS

Finally, 119 patients were included in this study (45 orthognathic mandible, 74 retrognathic mandible). The minor allele G in rs4444903 (EGF) was statistically more frequent in individuals with an orthognathic mandible (p = 0.008). The haplotype formed by the mutant alleles for rs4444903|rs2237051 (EGF; G|A) was statistically more frequent in the orthognathic mandible group (p = 0.007). The SNPs rs4444903 and rs2237051 in EGF, and rs2227983 in EGFR were statistically associated with a decreasing risk of developing a retrognathic mandible according to univariate and multivariate statistical analysis (p < 0.05).

CONCLUSION

SNPs in EGF (rs4444903 and rs2237051) and EGFR (rs2227983) were associated with MR in our German sample and could be genetic biomarkers for early and individualized diagnostic identification of retrognathic mandibular development by means of genetic screening tests.

Genetic Polymorphisms of Estrogen Receptors α and β are Associated with Craniofacial Measurements in Patients With Dentofacial Deformity

Dentofacial deformities are characterized by abnormalities in craniofacial development that affects the individual's skeletal and occlusion, often causing functional and esthetic problems. In literature, there is an involvement of polymorphisms in estrogen receptor 1 (ESR1) and estrogen receptor 2 (ESR2) genes in craniofacial measurements. The aim of this study was to evaluate a possible association between polymorphisms in ESR1 (rs2234693 and rs9340799) and ESR2 (rs1256049 and rs4986938) genes with cephalometric measurements in individuals with dentofacial deformities. This cross-sectional study was performed with 158 individuals in the preoperative period of orthognathic surgery. The cephalometric measurements obtained through lateral cephalogram using Dolphin Imaging software. For genetic analysis, the DNA extracted from epithelial cells of the oral mucosa and were genotyped using the real-time polymerase chain reaction. The data found submitted to statistical analysis, through the Kolmogorov-Smirnov, Mann-Whitney, and Kruskal-Wallis tests, using the IBM SPSS software version 24.0. Considered a significance level of 0.05. We found association between polymorphisms and cephalometric measurements just in the female sex. The polymorphisms ESR1/rs9340799 ( P= 0.003), ESR1/rs2234693 ( P= 0.026), and ESR2/rs1256049 ( P= 0.046) were associated with the upper gonial angle (Ar-Go-N). The polymorphism ESR2/rs1256049 was also associated with the facial axis-rickets (NBa-PtGn) ( P= 0.004), anterior cranial base (SN) ( P= 0.036), and Y-axis (SGn-SN) ( P= 0.031).

Prevalence and associated factors of myofascial pain in orthognathic patients with skeletal class II malocclusion

Orthognathic patients with skeletal class II malocclusion frequently suffer from myofascial pain (MP).

PURPOSE

This study aimed to evaluate the prevalence and associated factors of MP in these patients.

METHODS

This cross-sectional study was performed in adult patients with skeletal Class II malocclusion requiring orthognathic surgery. They were divided according to the presence or absence of MP. The predictor variables were craniofacial morphology, sex, temporomandibular disorders, chronic pain, depression, and polymorphisms of dopamine receptors DRD2 (rs6275 and rs6276) and ANKK1 (rs1800497) genes. Data were submitted to statistical analyses using the linear regression model and Poisson regression with a significance level of 0.05.

RESULTS

Sixty-five individuals were selected, of which 50 (76.92%) were females. A total of 21 (32.3%) patients had MP. Individuals with MP showed a decrease in the mandible gonial angle (p = 0.042) and an increased risk of having temporomandibular joint (TMJ) disc displacement (p = 0.003), TMJ pain (p = 0.030), chronic pain (p = 0.001), and severe depression (p = 0.015). Additionally, individuals carrying AA and AG genotypes in rs6275, and CC genotype in rs6276, were more likely to have MP (p < 0.05).

CONCLUSION

In this study, 32.3% of skeletal class II orthognathic patients had MP, which was associated with a decreased gonial angle, TMJ disc displacement, TMJ pain, chronic pain, depression, and polymorphisms in the DRD2 gene.

Single nucleotide polymorphisms in runt-related transcription factor 2 and bone morphogenetic protein 2 impact on their maxillary and mandibular gene expression in different craniofacial patterns - A comparative study

Introduction:

This study aimed to evaluate if single nucleotide polymorphisms (SNPs) in runt-related transcription factor 2 (RUNX2) and bone morphogenetic protein 2 (BMP2) are associated with different craniofacial patterns. Furthermore, we also investigated if RUNX2 and BMP2 expression in the maxilla and mandible are differently expressed according to facial phenotypes and influenced by the SNPs in their encoding genes. Orthognathic patients were included.

Materials and Methods:

Lateral cephalometric radiographs were used to classify facial phenotypes based on Steiner's ANB and Ricketts’ NBa-PtGn angles. Bone samples from 21 patients collected during orthognathic surgery were used for the gene expression assays. DNA from 129 patients was used for genotyping the SNPs rs59983488 and rs1200425 in RUNX2 and rs235768 and rs1005464 in BMP2. The established alpha was 5%.

Results:

A statistically significant difference was observed in the relative BMP2 expression in the mandible between Class I and III participants (P = 0.042). Homozygous GG (rs59983488) had higher RUNX2 expression (P = 0.036) in the mandible. In maxilla, GG (rs1200425) had a higher BMP2 expression (P = 0.038).

Discussion:

In conclusion, BMP2 is expressed differently in the mandible of Class I and Class III participants. Genetic polymorphisms in RUNX2 and BMP2 are associated with their relative gene expression.