Influence of COL2A1-G1405S polymorphism on mandibular skeletal malocclusions: A genetic association study and in silico analysis.

OBJECTIVE: The current study aimed to assess the association between collagen type II alpha 1 chain (COL2A1) single nucleotide polymorphism (SNP: rs2070739; C>T; G1405S) and mandibular skeletal malocclusions in the population of Mazandaran (North Iran). DESIGN: During 13 months, 102 control samples, 81 samples with skeletal Class III malocclusion contributed by mandibular prognathism and 82 samples with skeletal Class II malocclusion contributed by mandibular retrognathism were screened. Cephalometric analysis was performed to determine the type of abnormalities. COL2A1-G1405S genotyping was performed using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. The HOPE tool was used to investigate the effect of COL2A1-G1405S on the three-dimensional structure of protein. RESULTS: Results showed that there is no significant correlation between genotypes and alleles related to COL2A1-G1405S and mandibular prognathism (CT genotype: p-value= 0.210; T allele: p-value= 0.222). On the other hand, an association was observed between COL2A1-G1405S and mandibular retrognathism (CT genotype: p-value= 0.008; T allele: p-value= 0.011). The outputs of the HOPE tool also showed that COL2A1-G1405S can disrupt the NC1 domain of the protein. CONCLUSIONS: Here, we provide evidence that COL2A1-G1405S polymorphism may have positive correlation with the risk of skeletal Class II malocclusion contributed by mandibular retrognathism in the population of Mazandaran. Given that the COL2A1-G1405S occurs in NC1 domain, it is possible that this domain plays an important role in signaling pathways related to ossification. So, we suggest that the study of COL2A1 SNPs can help researchers understand the significant role of this collagen in mandibular skeletal malocclusions.

Transforming Growth Factor Beta Receptor 2 (TGFBR2) Promoter Region Polymorphisms May Be Involved in Mandibular Retrognathism.

Skeletal malocclusions are common phenotypes in humans and have a strong influence on genetic factors. Transforming growth factor beta (TGFß) controls numerous functions of the human body, including cell proliferation, differentiation, and migration. Thus, this study is aimed at evaluating whether genetic polymorphisms in TGFB1 and its receptor TGFBR2 are associated with mandibular retrognathism in German children and adolescents. Children and teenagers older than 8 years in the mixed or permanent dentition were included in this study. Patients with syndromes and facial trauma and patients with congenital alterations were excluded. Digital cephalometric tracings were performed using the anatomical landmarks point A, point B, sella (S), and nasion (N). Patients that have a retrognathic mandible (SNB < 78°) were selected as case group, and the patients with an orthognathic mandible (SNB = 78°- 82°) were selected as the control group. Genomic deoxyribonucleic acid (DNA) from saliva was used to evaluate four genetic polymorphisms in TGFB1 (rs1800469 and rs4803455) and TGBR2 (rs3087465 and rs764522) using real-time PCR. Chi-square or Fisher exact tests were used to compare gender, genotype, and allele distribution among groups. Genotype distribution was calculated in an additive and recessive model. Haplotype analysis was also performed. The established alpha of this study was 5%. A total of 146 patients (age ranging from 8 to 18 years) were included in this epidemiological genetic study. The genetic polymorphism rs3087465 in TGFBR2 was associated with mandibular retrognathism. Carrying the AA genotype in the rs3087465 polymorphism decreased the chance of having mandibular retrognathism (odds ratio = 0.25, confidence interval 95% = 0.06 to 0.94, p = 0.045). None of the haplotypes was associated with mandibular retrognathism (p > 0.05). In conclusion, we found that the genetic polymorphism rs3087465 in the promoter region of the TGFBR2 was associated with mandibular retrognathism in Germans.

Mutación de novo en KAT6B, síndrome Say-Barber-Biesecker-Young-Simpson y trastorno específico del lenguaje / De novo KAT6B mutation, Say-Barber-Biesecker-Young-Simpson syndrome, and specific language impairment

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Association of Polymorphism rs67920064 in ADAMTS9 Gene with Mandibular Retrognathism in a Chinese Population.

BACKGROUND Mandibular retrognathism is a common oral and maxillofacial deformity that may cause a series of physical and psychological diseases. Many studies indicated that genetic factors play an important role in the occurrence of mandibular retrognathism. In this study, we assess the association between polymorphism rs67920064 in ADAMTS9 gene and mandibular retrognathism in a Chinese population. MATERIAL AND METHODS Sixty participants (20 to 45 y, mean age 32.79 y) were classified into Class I or mandibular retrognathism skeletal-facial profile groups in accordance with cephalometric parameters. Thirty patients with mandibular retrognathism were assigned to the subject group; the others were assigned to the control group. Cephalometric parameters including sella-nasion A point, SN point B, condylion-gnathion (Gn), and gonion-Gn were recorded. Saliva samples from these participants were collected and polymerase chain reaction-restriction fragment length polymorphism was used to distinguish different genotypes of the rs67920064 single nucleotide polymorphisms (SNPs).We evaluated the correlation between mandibular retrognathism and polymorphism rs67920064 in the ADAMTS9 gene. RESULTS The distribution of rs67920064 gene polymorphism in ADAMST9 gene conforms to Hardy-Weinberg equilibrium. The A point-nasion-B point angle of the participants with the GA genotype of the rs67920064 SNP showed significantly decreased values (P<0.05), but there was no difference in length of mandibular body. Beyond that, the chi-square test showed that the GA genotype of rs67920064 SNP was highly associated with mandibular retrognathism (P<0.05). CONCLUSIONS Our research shows that there is an association between polymorphism rs67920064 in the ADAMTS9 gene and mandibular retrognathism in the Chinese population. Individuals with the GA phenotype are more likely to have mandibular retrognathism.

The ADAMTS9 gene is associated with mandibular retrusion in a Chinese population.

OBJECTIVE: Many studies suggest that genetics plays an important role in mandibular retrusion. In this study, we hypothesized that single nucleotide polymorphisms (SNPs) of ADAMTS9 gene is associated with mandibular retrusion in a Han Chinese population. METHODS: Saliva samples from 60 patients undergoing orthodontic for correction of malocclusion were collected. 130 SNPs genotyping of ADAMTS9 was used to asses the association of polymorphisms with the mandibular retrusion. The general linear model using age,gender and ANB as covariates weighed the relationship between SNP and mandibular retrusion. Additionally we leveraged the generalized multifactor dimensionality reduction (GMDR) method to investigate SNP-SNP interactions. The significance level was set at P < 0.05 in this study. RESULTS: The general linear model results showed that four SNPs (rs1014640,rs7648540,rs75839462 and rs4605539) in the ADAMTS9 gene may be related to the occurrence of mandibular retrusion,even after Bonferroni correction. In addition, we further found that the interaction between the ADAMTS9 rs75839462 and ADAMTS9 rs80118777 promoted the occurrence of mandibular retrusion. CONCLUSION: Our finding suggest that the ADAMTS9 gene may cause mandibular retrsusion independently and through SNP-SNP interactions.

Measurement of inferior facial angle and prefrontal space ratio in first trimester fetuses with aneuploidies: a retrospective study.

Objective To determine whether the measurement of inferior facial angle (IFA) and prefrontal space ratio (PFSR) in two-dimensional (2D) ultrasound images in the first trimester of pregnancy is reliable and to describe these markers in normal and aneuploid fetuses. Methods IFA and PFSR were measured in stored 2D midsagittal images of 200 normal and 140 aneuploid fetal profiles between 11 + 0 and 13 + 6 weeks of gestation. Limits of agreement (LOAs) and intraclass correlation coefficients (ICCs) for inter- and intraobserver differences were calculated. Results The mean IFA in normal fetuses was 76.5° ± 6.3. Between the two measurement rounds of the same observer, the LOAs were -5.4 to 7.1 (obs. 1) and 7.4 to 8.4 (obs. 2). For IFA measurements by the same observer the ICC was 0.88 (obs. 1) and for measurements by two different observers the ICC was 0.74. The mean PFSR was 0.76 ± 0.40 and the intraobserver LOAs were -0.372 to 0.395 (obs. 1) and -0.555 to 0.667 (obs. 2). For PFSR measurements by the same observer the ICC was 0.89 (obs. 1) and for measurements by two different observers the ICC was 0.65. Among aneuploid fetuses, IFA was below the normal range in one third of the cases with trisomy 18. PFSR was below the 95% prediction limit in 16.2% of fetuses with trisomy 21% and 17.9% of fetuses with trisomy 18. Conclusion IFA can be reliably measured in 2D ultrasound images in the first trimester of pregnancy with a high interobserver agreement and may provide information about retrognathia associated with various syndromes and aneuploidies at early stages of pregnancy.

Mutations in FGFR3 gene associated with maxillary retrognathism.

CONTEXT: Understanding the role of fibroblast growth factor receptor (FGFR) in the regulation of bone development and disease will ultimately lead to better prevention and treatment of related bone deformities and disorders. AIMS: To evaluate the role of gene FGFR3 in individuals with retrognathic maxilla by polymerase chain reaction (PCR) technique at molecular level and evaluate the significance of the same. SETTINGS AND DESIGN: Hospital based fundamental research involving individuals having maxillary retrognathism. METHODOLOGY: A total of 62 individuals (30M and32F) who were willing to take part in the study were selected from cephalometric measurements of N I A and the length PNS to ANS. The institution based basic genetic research study involved collection of fresh blood samples, DNA extraction, PCR analysis, and amplification using the specifically designed forward and reverse primers for targeting the commonly occurring mutations in FGFR3 gene. Further the products were sequenced to evaluate the presence of any novel mutations. RESULTS: The targeted single-nucleotide polymorphisms, at position 1138 in exon 10 of the FGFR3 gene were not identified in the analyzed blood samples. The detailed sequencing of full gene revealed the presence of 2 novel mutations, Exon 3: A213G and Exon 3: A223A/G in one individual. CONCLUSIONS: The present study indicated 2 novel mutations in gene FGFR3 in individual with maxillary retrognathism. The genetic-environmental interactions might have played a significant role in the expression of retrognathic maxilla.

Relationship between matrilin-1 gene polymorphisms and mandibular retrognathism.

INTRODUCTION: Mandibular retrognathism is a type of malocclusion that refers to an abnormal posterior position of the mandible as a result of a developmental abnormality. From the literature, it is evident that the mandibular growth pattern is determined by the intramembranous ossification of the mandibular body and endochondral ossification of the condyle. Matrilin-1 is a cartilage extracellular matrix protein, and matrilin-1 gene (MATN1) polymorphisms have been found to be involved in dental malocclusions of humans. In this study, we aimed to examine the association between MATN1 polymorphisms and the risk of mandibular retrognathism, in a case-control study with a South Indian population. METHODS: Eighty-one patients with mandibular retrognathism (SNB, <78°) and 71 controls having an orthognathic mandible (SNB, 80° ± 2°) were recruited. In both the patient and control groups, subjects with an orthognathic maxilla (SNA, 82° ± 2°) were included. Three single nucleotide polymorphisms of the MATN1 gene (rs1149048, rs1149042, and rs1065755) were genotyped using polymerase chain reaction-restriction fragment length polymorphism. The statistical association analysis was performed using the chi-square test. Pair-wise linkage disequilibrium was computed, and haplotypes were compared between subjects and controls. Nonparametric tests were used to compare cephalometric measurements between groups. RESULTS: No polymorphic site deviated from Hardy-Weinberg equilibrium in the controls. The rs1149042 genotypes and alleles were found to be associated with reduced risk of mandibular retrognathism. Furthermore, rs1149042 genotypes were associated with mandibular measurements (SNB and ANB). There was no strong and consistent linkage disequilibrium linkage disequilibrium across two different single nucleotide polymorphisms and haplotypes were not associated with mandibular retrognathism. CONCLUSIONS: The results of our study suggest an association between the MATN1 gene polymorphisms and mandibular retrognathism.

Genetic response in masseter muscle after orthognathic surgery in comparison with healthy controls - A Microarray study.

One third of adult patients with orthognathic surgery of a prognathic or retrognathic mandible show relapse. The sagittal split osteotomy of the mandible leads to a displacement of both parts up to 10 mm without any changes of muscle attachment. Changed mandible length needs adaptation of muscle capacity because of changed force to moment ratio. The aim of this Microarray study was to analyze the general genetic response of masseter muscle in patients with retrognathism or prognathism of the mandible six months after surgery in comparison with healthy untreated controls. We found in tissue samples from masseter muscle a reduction of different entities between patients and controls but less in retrognathic than in prognathic patients (274/429). The different entities to controls in prognathia were reduced from 1862 to 1749 but increased in retrognathia from 1070 to 1563. We have to consider that the total amount of different entities to the controls is higher in patients with prognathic mandible (7364) because of their strong genetic controlled development compared with that in patients with retrognathic mandible (4126), which is more environmentally influenced. It can be concluded that function follows form after surgical change with high inheritance. In retrognathic patients the adaptation could be delayed or the capacity of regeneration potential is not sufficient.

Role of myosin 1H gene polymorphisms in mandibular retrognathism.

INTRODUCTION: Mandibular retrognathism may be the result of a developmental abnormality or the unfavorable positional relationship of developing jaws. Several lines of evidence suggest that muscles are known to have extensive mutual effects on bones. Studies with immunohistochemical staining and gene expression have shown unique combinations of myosin heavy chain isoforms in the masseter muscles. In this study, we aimed to evaluate MYO1H gene polymorphisms and haplotypes as risk factors for mandibular retrognathism. METHODS: Twenty-five subjects with mandibular retrognathism and 25 control subjects of both sexes having an orthognathic maxilla (SNA, 82° ± 2°) between the ages of 12 and 30 years of age were selected for this study. Based on the cephalometric values, subjects with SNB angles smaller than 78° were considered to have mandibular retrognathism. Orthognathic subjects (SNB, 80°) without jaw deformations were used as the comparison group. Three polymorphisms of MYO1H gene (rs10850110, rs11611277, and rs3825393) were genotyped using polymerase chain reaction and restriction fragment length polymorphism. Associations were tested with the Pearson chi-square test and haplotype analyses. RESULTS: The single nucleotide polymorphism rs3825393 showed a statistically significant association with mandibular retrognathism. The cephalometric variables SNB and ANB angles showed significant differences among the various genotypes of rs3825393. Linkage disequilibrium was not strong and significant between the single nucleotide polymorphisms; hence, the haplotypes of the MYO1H gene are not associated with mandibular retrognathism. CONCLUSIONS: These results suggest that the rs3825393 polymorphism of the MYO1H gene is associated with an increased risk for mandibular retrognathism. The relatively small sample size used in the study resulted in modest statistical power. A parallel investigation on another population with larger samples to increase the power could further clarify the role of the MYO1H gene in causing mandibular retrognathism.

Neonatal detection of 5p13.2 duplication and delineation of the phenotype.

A newborn boy with broad forehead, mild microretrognathia, large hands and feet, arachnodactyly and a cortical thumb also had left renal agenesis, dysgenesis of corpus callosum with psychomotor delay. After olignucleotide array comparative genomic hybridization (array-CGH) analysis, we detected a 900 kb duplication in cytoband 5p13.2, apperently a first clinical description.

Grouping patients for masseter muscle genotype-phenotype studies.

OBJECTIVES: To use various facial classifications, including either/both vertical and horizontal facial criteria, to assess their effects on the interpretation of masseter muscle (MM) gene expression. MATERIALS AND METHODS: Fresh MM biopsies were obtained from 29 patients (age, 16-36 years) with various facial phenotypes. Based on clinical and cephalometric analysis, patients were grouped using three different classifications: (1) basic vertical, (2) basic horizontal, and (3) combined vertical and horizontal. Gene expression levels of the myosin heavy chain genes MYH1, MYH2, MYH3, MYH6, MYH7, and MYH8 were recorded using quantitative reverse transcriptase polymerase chain reaction (RT-PCR) and were related to the various classifications. The significance level for statistical analysis was set at P ≤ .05. RESULTS: Using classification 1, none of the MYH genes were found to be significantly different between long face (LF) patients and the average vertical group. Using classification 2, MYH3, MYH6, and MYH7 genes were found to be significantly upregulated in retrognathic patients compared with prognathic and average horizontal groups. Using classification 3, only the MYH7 gene was found to be significantly upregulated in retrognathic LF compared with prognathic LF, prognathic average vertical faces, and average vertical and horizontal groups. CONCLUSION: The use of basic vertical or basic horizontal facial classifications may not be sufficient for genetics-based studies of facial phenotypes. Prognathic and retrognathic facial phenotypes have different MM gene expressions; therefore, it is not recommended to combine them into one single group, even though they may have a similar vertical facial phenotype.

Cleft palate, retrognathia and congenital heart disease in velo-cardio-facial syndrome: a phenotype correlation study.

OBJECTIVE: Velo-cardio-facial syndrome (VCFS) is caused by a microdeletion of approximately 40 genes from one copy of chromosome 22. Expression of the syndrome is a variable combination of over 190 phenotypic characteristics. As of yet, little is known about how these phenotypes correlate with one another or whether there are predictable patterns of expression. Two of the most common phenotypic categories, congenital heart disease and cleft palate, have been proposed to have a common genetic relationship to the deleted T-box 1 gene (TBX1). The purpose of this study is to determine if congenital heart disease and cleft palate are correlated in a large cohort of human subjects with VCFS. METHODS: This study is a retrospective chart review including 316 Caucasian non-Hispanic subjects with FISH or CGH microarray confirmed chromosome 22q11.2 deletions. All subjects were evaluated by the interdisciplinary team at the Velo-Cardio-Facial Syndrome International Center at Upstate Medical University, Syracuse, NY. Each combination of congenital heart disease, cleft palates, and retrognathia was analyzed by Chi square or Fisher exact test. RESULTS: For all categories of congenital heart disease and cleft palate or retrognathia no significant associations were found, with the exception of submucous cleft palate and retrognathia (nominal p=0.0325) and occult submucous cleft palate and retrognathia (nominal p=0.000013). CONCLUSIONS: Congenital heart disease and cleft palate do not appear to be correlated in human subjects with VCFS despite earlier suggestions from animal models. Possible explanations include modification of the effect of TBX1 by genes outside of the 22q11.2 region that may further influence the formation of the palate or heart, or the presence of epigenetic factors that may effect genes within the deleted region, modifying genes elsewhere, or polymorphisms on the normal copy of chromosome 22. Lastly, it is possible that TBX1 plays a role in palate formation in some species, but not in humans. In VCFS, retrognathia is caused by an obtuse angulation of the skull base. It is unknown if the correlation between retrognathia and cleft palate in VCFS indicates a developmental sequence related to skull morphology, or direct gene effects of both anomalies. Much work remains to be done to fully understand the complex relationships between phenotypic characteristics in VCFS.

Dicer activity in neural crest cells is essential for craniofacial organogenesis and pharyngeal arch artery morphogenesis.

MicroRNAs (miRNAs) play important roles in regulating gene expression during numerous biological/pathological processes. Dicer encodes an RNase III endonuclease that is essential for generating most, if not all, functional miRNAs. In this work, we applied a conditional gene inactivation approach to examine the function of Dicer during neural crest cell (NCC) development. Mice with NCC-specific inactivation of Dicer died perinatally. Cranial and cardiac NCC migration into target tissues was not affected by Dicer disruption, but their subsequent development was disturbed. NCC derivatives and their associated mesoderm-derived cells displayed massive apoptosis, leading to severe abnormalities during craniofacial morphogenesis and organogenesis. In addition, the 4th pharyngeal arch artery (PAA) remodeling was affected, resulting in interrupted aortic arch artery type B (IAA-B) in mutant animals. Taken together, our results show that Dicer activity in NCCs is essential for craniofacial development and pharyngeal arch artery morphogenesis.

A novel mutation in the C-terminal region of RUNX2/CBFA1 distal to the DNA-binding runt domain in a Japanese patient with cleidocranial dysplasia.

Cleidocranial dysplasia (CCD) is an autosomal dominant inherited skeletal disease with high penetrance and variable expressivity. Although many mutations in RUNX2/CBFA1, an osteoblast-specific transcription factor, have been identified as causes of CCD, it is unclear whether these mutation genotypes relate to various symptoms. Heterogeneous mutations of RUNX2/CBFA1 result in disease characterized by abnormal skeletal genesis and dental disorders. There are few reports describing the relation between detailed orofacial pathology and the RUNX2/CBFA1 genotype. The case of a Japanese patient with severe orofacial dysplasia who was clinically thought to have CCD is described here. The authors performed mutation analysis on the RUNX2/CBFA1 gene and identified a novel frameshift mutation (722delT), which produces a mutant RUNX2/CBFA1 with a truncating C-terminus distal to the runt domain.

Freeman-Sheldon (whistling face) syndrome with hyperpyrexia in the newborn: case report.

Freeman Sheldon syndrome (FSS) is a rare, multiple congenital contracture syndrome that is relatively well-known, since affected children have a striking appearance. This entity was historically referred to as the "whistling-face syndrome". Malignant hyperthermia and hyperpyrexia have been documented in FSS after general anesthesia related to the neuropathy. We report a male neonate with FSS and hyperpyrexia without anesthesia. To our knowledge, our patient is the first in the literature with hyperpyrexia in the newborn period without anesthesia.

Denuded congenital lesions: recessive dystrophic epidermolysis bullosa.

Recessive dystrophic epidermolysis bullosa (Hallopeau-Siemens type) (RDEB-HS) is a rare severe mechanobullous disorder resulting from a defect in collagen VII. Patients with RDEB-HS present with generalized blistering and denudation of the skin at birth and have mucosal involvement. The repeated blistering leads to scarring, which may be deforming and result in serious complications. Transmission electron microscopy is currently the gold standard for diagnosis of RDEB-HS.

Cervical vertebrae, cranial base, and mandibular retrognathia in human triploid fetuses.

On profile radiographs of adults, an association between fusions of cervical vertebrae, deviations in the cranial base and mandibular retrognathia has been documented radiographically. An elaboration of this association on a histological level is needed. In human triploid fetuses severe mandibular retrognathia and deviations in the cranial base have previously been described radiographically (without cephalometry) and cervical column fusions radiographically as well as histologically. Therefore, triploid fetuses were chosen to elucidate the cranial base cephalomterically and histologically. In the present study, eight triploid fetuses were analyzed radiographically and histologically focusing especially on the cranial base, which borders to the spine and to which the jaws are attached. A histological analysis of the cranial base has not previously been performed in triploid cases. An enlarged cranial base angle and a retrognathic position of the mandible were documented cephalometrically on radiographs of all cases. Histologically, malformations were observed in the cranial base as well as in the spine. These are new findings indicating the association between the occipital bone and the uppermost vertebra in the body axis. As the notochord connects the cervical column and the cranial base in early prenatal life, molecular signaling from the notochord may in future studies support the notochord as the developmental link between abnormal development in the spine and the cranial base.

[Review of literature and results from test matings of East Friesian milk sheep affected with brachygnathia inferior]. / Literaturübersicht und Ergebnisse eines Zuchtversuchs zur Brachygnathia inferior beim Ostfriesischen Milchschaf.

Shortness of the lower jaw (brachygnathia inferior, underbite, overshot, parrot mouth) is an inborn and mostly hereditary malformation often seen in many sheep breeds. Chromosomal anomalies are generally not involved in brachygnathia inferior. Viral infections, teratogenic drugs and alkaloids of plants often lead to craniofacial malformations associated with brachygnathia inferior. A maternal deficiency of iron is discussed as a cause for brachygnathia inferior. We performed a three-year breeding trial using mainly East Friesian milk sheep affected by brachygnathic occlusion. Mating schemes included affected by affected and affected by unaffected matings. In the breeding trial, 60 lambs were born and from these 37 animals had variable degrees of brachygnathia inferior. The brachygnathic condition increased with rising age of the lambs. Extremely affected lambs showed palatine ulcers and growth retardation. Moreover, some animals had abnormal positions of the incisor teeth, distortion of the lower jaw and deformities of the external ear. Analysis of the pedigree did not support a monogenic inheritance pattern. An oligogenic inheritance including a dominant and recessive locus responsible for the major gene effects and possibly further modifying loci appeared much more likely. Other causes for brachygnathia inferior such as viral infections and anemia of the ewes could be ruled out. Chromosomal abnormalities were not evident and thus, large chromosomal defects were not associated with brachygnathia inferior.

Cervical column morphology in patients with skeletal Class III malocclusion and mandibular overjet.

INTRODUCTION: The cervical column morphology of adults with skeletal Class III malocclusion and mandibular overjet was examined and compared with the cervical column morphology of a control group with neutral occlusion and normal craniofacial morphology. METHODS: The mandibular overjet group consisted of 57 patients (32 women, 25 men). The control group consisted of 21 subjects (15 women, 6 men). A visual assessment of the cervical column and measurements of the craniofacial dimensions were performed on a profile radiograph of each subject. RESULTS: In the mandibular overjet group, 61.4% had cervical column fusion, and 12.3% had posterior arch deficiency. Morphologic cervical column deviations occurred significantly more often in the mandibular overjet group than in the control group (P <.001). The most important craniofacial parameters for fusion of the cervical column were maxillary retrognathism (P <.05) and mandibular overjet (P <.05) (R2 = 0.22). The most important factor for posterior arch deficiency was mandibular inclination (P <.05) (R2 = 0.12). CONCLUSIONS: These results are considered an important first step in phenotypic differentiation of skeletal Class III malocclusions that can be associated with different genotypes. This is important for the diagnosis and the correct treatment of these patients.