Evaluation of facial soft-tissue values and craniofacial morphology in obese adolescent patients with different skeletal classes

Objectives: The purpose of this study was to evaluate the facial soft tissue and craniofacial morphological structures in adolescent obese individuals with different skeletal patterns. Materials and Methods: The study was carried out on 292 adolescents examined under three groups based on their body mass indexes (BMIs) as obese, healthy, and overweight. The subjects were also categorized based on skeletal classes as Class I, Class II, and Class III. Results: The glabella, nasion, labiale inferius, labiomentale, and pogonion values of the female patients were significantly higher in obese group. In the obese and overweight groups, effective midfacial and mandibular length, anterior and posterior facial heights, and SN values of the females were higher than males. In the obese group, the mean effective midfacial and mandibular length (Co-A and Co-Gn), anterior and posterior facial heights (S-Go and N-Me), and anterior cranial base (SN) values were significantly higher than other groups. Conclusion: Soft-tissue thicknesses increase as BMI value increases. Craniofacial morphology reveals significant differences between BMI groups.

Craniofacial morphology and growth in Muenke syndrome, Saethre-Chotzen syndrome, and TCF12-related craniosynostosis

Objectives To determine whether the midface of patients with Muenke syndrome, Saethre-Chotzen syndrome, or TCF12-related craniosynostosis is hypoplastic compared to skeletal facial proportions of a Dutch control group. Material and methods We included seventy-four patients (43 patients with Muenke syndrome, 22 patients with Saethre-Chotzen syndrome, and 9 patients with TCF12-related craniosynostosis) who were referred between 1990 and 2020 (age range 4.84 to 16.83 years) and were treated at the Department of Oral Maxillofacial Surgery, Special Dental Care and Orthodontics, Children’s Hospital Erasmus University Medical Center, Sophia, Rotterdam, the Netherlands. The control group consisted of 208 healthy children. Results Cephalometric values comprising the midface were decreased in Muenke syndrome (ANB: β = –1.87, p = 0.001; and PC1: p < 0,001), Saethre-Chotzen syndrome (ANB: β = –1.76, p = 0.001; and PC1: p < 0.001), and TCF12-related craniosynostosis (ANB: β = –1.70, p = 0.015; and PC1: p < 0.033). Conclusions In this study, we showed that the midface is hypoplastic in Muenke syndrome, Saethre-Chotzen syndrome, and TCF12-related craniosynostosis compared to the Dutch control group. Furthermore, the rotation of the maxilla and the typical craniofacial buildup is significantly different in these three craniosynostosis syndromes compared to the controls. Clinical relevance The maxillary growth in patients with Muenke syndrome, Saethre-Chotzen syndrome, or TCF12-related craniosynostosis is impaired, leading to a deviant dental development. Therefore, timely orthodontic follow-up is recommended. In order to increase expertise and support treatment planning by medical and dental specialists for these patients, and also because of the specific differences between the syndromes, we recommend the management of patients with Muenke syndrome, Saethre-Chotzen syndrome, or TCF12-related craniosynostosis in specialized multidisciplinary teams.

Bite force performance from wild derived mice has undetectable heritability despite having heritable morphological components

Fitness-related traits tend to have low heritabilities. Conversely, morphology tends to be highly heritable. Yet, many fitness-related performance traits such as running speed or bite force depend critically on morphology. Craniofacial morphology correlates with bite performance in several groups including rodents. However, within species, this relationship is less clear, and the genetics of performance, morphology and function are rarely analyzed in combination. Here, we use a half-sib design in outbred wild-derived Mus musculus to study the morphology-bite force relationship and determine whether there is additive genetic (co-)variance for these traits. Results suggest that bite force has undetectable additive genetic variance and heritability in this sample, while morphological traits related mechanically to bite force exhibit varying levels of heritability. The most heritable traits include the length of the mandible which relates to bite force. Despite its correlation with morphology, realized bite force was not heritable, which suggests it is less responsive to selection in comparison to its morphological determinants. We explain this paradox with a non-additive, many-to-one mapping hypothesis of heritable change in complex traits. We furthermore propose that performance traits could evolve if pleiotropic relationships among the determining traits are modified.

Rare case of skeletal third class in a subject suffering from Solitary Median Maxillary Central Incisor syndrome (SMMCI) associated to panhypopituitarism

Background The median solitary maxillary central incisor syndrome (SMMCI) is a rare malformative syndrome consisting of multiple defects, mainly found on the body midline. It can be correlated to the etiopathological and phenotypic pattern of panhypopituitarism. This case-report describes the rare case of a patient suffering from SMMCI and panhypopituitarism, showing an unusual craniofacial morphology. Case presentation From the cephalometric analysis, a skeletal class III was identified (despite the other cases described in literature described as skeletal class II), derived from hypomaxillia and mandibular protrusion. A convex lip profile, with tendency to mandibular hyper-divergency, airway patency, anterior and posterior cross-bite were observed. At the clinical examination, a maxillary cant was evident on the frontal plane that appeared asymmetric, with the prevalence of the third lower part of the face. There were some dysmorphic signs such as: small nose, rectilinear eyelid line and reduced interocular distance. Conclusions The present clinical case shows how, despite the literature, SMMCI can be associated with a III skeletal class, with maxillary hypoplasia and mandibular protrusion. The interdisciplinary collaboration between dentist and pediatrician is therefore important for the early interception of the malocclusions associated with these syndromes.

Tricho-Dento-Osseous Syndrome: A Report of a Familial Cluster and a Literature Review

Tricho-dento-osseous syndrome (TDO), is a very rare, autosomal dominant genetic disorder, commonly characterized by curly hair at infancy, severe enamel hypomineralization and hypoplasia with taurodontism teeth, bone defects and other deformities. Other phenotypic features include flat fingernails and altered craniofacial morphology. A genetic linkage has been identified on chromosome 17q21 in the DLX3 gene. Treatment plan of TDO is to prevent problems such as sensitivity and dental attrition of the hypoplastic structure of the tooth, to promote the esthetics and encourage self-confidence of the patient. In this case report, we present a family with the proband father, and the two children siblings affected by the TDO syndrome. We describe clinical and radiological features, along with dental characteristics and genetic background. Management of TDO syndrome necessitates a multidisciplinary approach, appropriate documentation, and long-term follow up.

RELATION BETWEEN SAGITTAL POSITION OF THE MANDIBLE AND PHARYNGEAL AIRWAY VOLUME IN ADULTS USING CONE BEAM COMPUTED TOMOGRAPHY

Introduction: Many authors have discussed the relationship between craniofacial morphology and pharyngeal airway spaces in different malocclusions and skeletal patterns. So the aim of this work was to study the relation between sagittal position of the mandible and pharyngeal airway volume in adults using CBCT. Materials And Methods:Twentyone CBCT radiographs were collected from the archive of Radiology Department at Suez Canal University and were divided into 3 groups according to the measured SNB angle. Group 1 normal mandibular position, group 2 retrognathic mandible and group 3 prognathic mandible. Dolphin 3D imaging software was used to measure the airway volume for all the radiographs. Nasopharyngeal, oropharyngeal, hypopharyngeal and total pharyngeal airway volumes were measured for all the radiographs. F-test (ANOVA) was used for comparison between groups and Tukey test for pairwise comparisons. Correlations between variables were tested using PearsonÂ’s correlation coefficient. Results: there was statistically significant difference in the mean total pharyngeal airway volume and oropharyngeal airway volumes between the three groups. Nasopharyngeal airway volume and hypopharyngeal airway volume had non-significant difference between groups. There was a significant positive correlation between total pharyngeal airway volume (mm3) and SNB angle. Conclusion: Pharyngeal airway volume differs with different sagittal positions of the mandible. Pharyngeal airway volume decreases with mandibular retrognathism and increases with mandibular prognathism.

Polygenic sex determination produces modular sex polymorphism in an African cichlid fish

For many vertebrates, a single genetic locus initiates a cascade of developmental sex differences in the gonad and throughout the organism, resulting in adults with two, phenotypically distinct sexes. Species with polygenic sex determination (PSD) have multiple interacting sex determination alleles segregating within a single species, allowing for more than two genotypic sexes, and scenarios where sex genotype at a given locus can be decoupled from gonadal sex. Here we investigate the effects of PSD on secondary sexual characteristics in the cichlid fish Metriaclima mbenjii, where one female (W) and one male (Y) sex determination allele interact to produce siblings with four possible sex classes: ZZXX females, ZWXX females, ZWXY females, and ZZXY males. We find that PSD in M. mbenjii produces an interplay of sex-linkage and sex-limitation resulting in modular variation in morphological and behavioral traits. Further, the evolution or introgression of a novel sex determiner creates additional axes of phenotypic variation for varied traits, including genital morphology, craniofacial morphology, gastrointestinal morphology, and home tank behaviors. In contrast to single-locus sex determination, which broadly results in sexual dimorphism, polygenic sex determination can induce higher-order sexual polymorphism. The modularity of secondary sexual characteristics produced by PSD provides novel context for understanding the evolutionary causes and consequences of maintenance, gain, or loss of sex determination alleles in populations.

The first transchromosomic rat model with human chromosome 21 shows robust Down syndrome features

Progress in earlier detection and symptom management has increased life expectancy and quality of life in people with Down syndrome (DS). However, no drug has been approved to help individuals with DS live independently and fully. Although rat models could support more robust physiological, behavioral, and toxicology analysis than mouse models during preclinical validation, no DS rat model is available due to technical challenges. We developed the first transchromosomic rat model of DS, TcHSA21rat, which contains a freely segregating, EGFP-inserted, human chromosome 21 (HSA21) with >93% of its protein coding genes. RNA-Seq of neonatal forebrains demonstrates that TcHSA21rat not only expresses HSA21 genes but also has an imbalance in global gene expression. Using EGFP as a marker for trisomic cells, flow cytometry analyses of peripheral blood cells from 361 adult TcHSA21rat animals show that 81% of animals retain HSA21 in >80% of cells, the criterion for a "Down syndrome karyotype" in people. TcHSA21rat exhibits learning and memory deficits and shows increased anxiety and hyperactivity. TcHSA21rat recapitulates well-characterized DS brain morphology, including smaller brain volume and reduced cerebellar size. In addition, the rat model shows reduced cerebellar foliation, a prominent feature of DS that is not observed in DS mouse models. Moreover, TcHSA21rat exhibits anomalies in craniofacial morphology, heart development, husbandry, and stature. TcHSA21rat is a robust DS animal model that can facilitate DS basic research and provide a unique tool for preclinical validation to accelerate DS drug development.

Forebrain Architecture and Development in Cyclostomes, with Reference to the Early Morphology and Evolution of the Vertebrate Head

The vertebrate head and brain are characterized by highly complex morphological patterns. The forebrain, the most anterior division of the brain, is subdivided into the diencephalon, hypothalamus, and telencephalon from the neuromeric subdivision into prosomeres. Importantly, the telencephalon contains the cerebral cortex, which plays a key role in higher order cognitive functions in humans. To elucidate the evolution of the forebrain regionalization, comparative analyses of the brain development between extant jawed and jawless vertebrates are crucial. Cyclostomes – lampreys and hagfishes – are the only extant jawless vertebrates, and diverged from jawed vertebrates (gnathostomes) over 500 million years ago. Previous developmental studies on the cyclostome brain were conducted mainly in lampreys because hagfish embryos were rarely available. Although still scarce, the recent availability of hagfish embryos has propelled comparative studies of brain development and gene expression. By integrating findings with those of cyclostomes and fossil jawless vertebrates, we can depict the morphology, developmental mechanism, and even the evolutionary path of the brain of the last common ancestor of vertebrates. In this review, we summarize the development of the forebrain in cyclostomes and suggest what evolutionary changes each cyclostome lineage underwent during brain evolution. In addition, together with recent advances in the head morphology in fossil vertebrates revealed by CT scanning technology, we discuss how the evolution of craniofacial morphology and the changes of the developmental mechanism of the forebrain towards crown gnathostomes are causally related.