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Punjabi N, Vacaru A, Inman JC. 3D Genial Tubercle Anatomic Considerations in Genioglossus Advancement Surgery. Otolaryngol Head Neck Surg 2024. [PMID: 39031714 DOI: 10.1002/ohn.870] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2024] [Revised: 05/22/2024] [Accepted: 06/05/2024] [Indexed: 07/22/2024]
Abstract
OBJECTIVE To qualitatively describe variation in morphology of the genial tubercle and quantify the spatial relationship between the tubercle and genioglossus muscle. STUDY DESIGN Case series. SETTING Cadaver dissection. METHODS Segmental sections of the mandible, with muscular attachments intact, were harvested from 18 fresh cadaver heads. Three-dimensional laser scans, with a resolution of 0.025 mm, were taken of each specimen with muscle attached and repeated after muscle removal. The genioglossus muscular attachment was measured relation to bony landmarks. RESULTS The morphology of the genial tubercle varied, with anywhere from 1 large spine to 4 individual spines. However, all specimens had a distinguishable superior portion of the tubercle, where the genioglossus attached, and an inferior portion, where the geniohyoid attached. The height of the superior tubercle (ST) was 6.1 mm (95% confidence inerval [CI]: 5.7-6.5). The height of the genioglossus muscle above the peak amplitude of the ST was 4.3 mm (3.8-4.9), but only 2.5 mm (2.0-3.0) below. On average, 64.4% (58.6-70.2) of the height of the genioglossus muscle attachment was above the peak. Overall, 19.5% (14.1-25.0) of the muscle surface area extended beyond the boundaries of the tubercle. CONCLUSION The genioglossus muscle attachment originates from the superior genial tubercle, which has a variable topography and amplitude. However, the muscle is not centered on the spines-more of the muscular fibers attach above the spine as compared to below. This new data may explain the genioglossus advancement "miss rate"-failure to advance muscle on initial osteotomy-of 39-78% reported in the literature.
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Affiliation(s)
- Nihal Punjabi
- Department of Otolaryngology-Head and Neck Surgery, Loma Linda University Medical Center, Loma Linda, California, USA
- Case Western Reserve University School of Medicine, Cleveland, Ohio, USA
| | - Alexandra Vacaru
- Loma Linda University School of Medicine, Loma Linda, California, USA
| | - Jared C Inman
- Department of Otolaryngology-Head and Neck Surgery, Loma Linda University Medical Center, Loma Linda, California, USA
- Loma Linda University School of Medicine, Loma Linda, California, USA
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Fernández-Rubio EM, Radlanski RJ. Development of the human primary and secondary jaw joints. Ann Anat 2024; 251:152169. [PMID: 37875166 DOI: 10.1016/j.aanat.2023.152169] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2023] [Revised: 09/26/2023] [Accepted: 10/09/2023] [Indexed: 10/26/2023]
Abstract
This study investigates the development of the primary and secondary jaw joints in humans, focusing on their concomitance and subsequent disconnection. Development begins with the primary temporomandibular joint as a connection between Meckel's cartilage and the incus, while the secondary temporomandibular joint develops anteriorly as an articulation between the mandibular condyle and the mandibular fossa. Previous research in mice has provided insights into the morphogenesis of these joints, but their specific development of the 3D morphogenesis in humans remains unclear. To address this gap, histological serial sections of embryos and fetuses ranging from 19 to 230 mm crown-rump length were analyzed. The 3D morphogenesis of the middle ear and the temporomandibular joint was examined, paying attention to the morphological characteristics, timing, and potential mechanisms of movement and disconnection. The primary jaw joint is initially formed at 25 mm (8th week), followed by the appearance of the secondary jaw joint arising at 87 mm (12th week). Both joints persist present simultaneously, until a separation occurs between 150 and 230 mm (18th-24th week). It is remarkable that both joints remain concomitant and function somehow for a period exceeding 6 weeks, with the mechanism of their separation still unclear. Understanding the precise timing and functional movements involved with these temporarily connected joints is crucial for comprehending the overall development of the temporomandibular joint. Further research is needed to explore the molecular and cellular processes underlying these developmental changes.
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Affiliation(s)
- E M Fernández-Rubio
- Charité - Campus Benjamin Franklin at Freie Universität Berlin Center for Dental and Craniofacial Sciences Dept. of Craniofacial Developmental Biology, Assmannshauser Str. 4-6, Berlin 14197, Germany
| | - R J Radlanski
- Charité - Campus Benjamin Franklin at Freie Universität Berlin Center for Dental and Craniofacial Sciences Dept. of Craniofacial Developmental Biology, Assmannshauser Str. 4-6, Berlin 14197, Germany.
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Long HK, Osterwalder M, Welsh IC, Hansen K, Davies JOJ, Liu YE, Koska M, Adams AT, Aho R, Arora N, Ikeda K, Williams RM, Sauka-Spengler T, Porteus MH, Mohun T, Dickel DE, Swigut T, Hughes JR, Higgs DR, Visel A, Selleri L, Wysocka J. Loss of Extreme Long-Range Enhancers in Human Neural Crest Drives a Craniofacial Disorder. Cell Stem Cell 2020; 27:765-783.e14. [PMID: 32991838 PMCID: PMC7655526 DOI: 10.1016/j.stem.2020.09.001] [Citation(s) in RCA: 77] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Revised: 06/09/2020] [Accepted: 09/02/2020] [Indexed: 01/09/2023]
Abstract
Non-coding mutations at the far end of a large gene desert surrounding the SOX9 gene result in a human craniofacial disorder called Pierre Robin sequence (PRS). Leveraging a human stem cell differentiation model, we identify two clusters of enhancers within the PRS-associated region that regulate SOX9 expression during a restricted window of facial progenitor development at distances up to 1.45 Mb. Enhancers within the 1.45 Mb cluster exhibit highly synergistic activity that is dependent on the Coordinator motif. Using mouse models, we demonstrate that PRS phenotypic specificity arises from the convergence of two mechanisms: confinement of Sox9 dosage perturbation to developing facial structures through context-specific enhancer activity and heightened sensitivity of the lower jaw to Sox9 expression reduction. Overall, we characterize the longest-range human enhancers involved in congenital malformations, directly demonstrate that PRS is an enhanceropathy, and illustrate how small changes in gene expression can lead to morphological variation.
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Affiliation(s)
- Hannah K Long
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA 94305, USA; Institute of Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Marco Osterwalder
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Ian C Welsh
- Program in Craniofacial Biology, Department of Orofacial Sciences and Department of Anatomy, Institute of Human Genetics, Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, University of California, San Francisco, San Francisco, CA, USA
| | - Karissa Hansen
- Program in Craniofacial Biology, Department of Orofacial Sciences and Department of Anatomy, Institute of Human Genetics, Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, University of California, San Francisco, San Francisco, CA, USA
| | - James O J Davies
- MRC Molecular Haematology Unit, MRC Weatherall Institute of Molecular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
| | - Yiran E Liu
- Cancer Biology Program, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Mervenaz Koska
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Alexander T Adams
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Biology, Stanford University, Stanford, CA 94305, USA
| | - Robert Aho
- Program in Craniofacial Biology, Department of Orofacial Sciences and Department of Anatomy, Institute of Human Genetics, Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, University of California, San Francisco, San Francisco, CA, USA
| | - Neha Arora
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Kazuya Ikeda
- Department of Pediatrics, Stanford University, Stanford, CA 94305, USA
| | - Ruth M Williams
- MRC Weatherall Institute of Molecular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
| | - Tatjana Sauka-Spengler
- MRC Weatherall Institute of Molecular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
| | - Matthew H Porteus
- Department of Pediatrics, Stanford University, Stanford, CA 94305, USA
| | - Tim Mohun
- The Francis Crick Institute, Mill Hill Laboratory, The Ridgeway, Mill Hill, London NW7 1AA, UK
| | - Diane E Dickel
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Tomek Swigut
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Jim R Hughes
- MRC Molecular Haematology Unit, MRC Weatherall Institute of Molecular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
| | - Douglas R Higgs
- MRC Molecular Haematology Unit, MRC Weatherall Institute of Molecular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, UK; Laboratory of Gene Regulation, MRC Weatherall Institute of Molecular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
| | - Axel Visel
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA; US Department of Energy Joint Genome Institute, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA; School of Natural Sciences, University of California, Merced, Merced, CA 95343, USA
| | - Licia Selleri
- Program in Craniofacial Biology, Department of Orofacial Sciences and Department of Anatomy, Institute of Human Genetics, Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, University of California, San Francisco, San Francisco, CA, USA
| | - Joanna Wysocka
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA 94305, USA; Institute of Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA; Howard Hughes Medical Institute, Stanford University School of Medicine, Stanford, CA 94305, USA.
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Svandova E, Anthwal N, Tucker AS, Matalova E. Diverse Fate of an Enigmatic Structure: 200 Years of Meckel's Cartilage. Front Cell Dev Biol 2020; 8:821. [PMID: 32984323 PMCID: PMC7484903 DOI: 10.3389/fcell.2020.00821] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Accepted: 08/03/2020] [Indexed: 12/16/2022] Open
Abstract
Meckel's cartilage was first described by the German anatomist Johann Friedrich Meckel the Younger in 1820 from his analysis of human embryos. Two hundred years after its discovery this paper follows the development and largely transient nature of the mammalian Meckel's cartilage, and its role in jaw development. Meckel's cartilage acts as a jaw support during early development, and a template for the later forming jaw bones. In mammals, its anterior domain links the two arms of the dentary together at the symphysis while the posterior domain ossifies to form two of the three ear ossicles of the middle ear. In between, Meckel's cartilage transforms to a ligament or disappears, subsumed by the growing dentary bone. Several human syndromes have been linked, directly or indirectly, to abnormal Meckel's cartilage formation. Herein, the evolution, development and fate of the cartilage and its impact on jaw development is mapped. The review focuses on developmental and cellular processes that shed light on the mechanisms behind the different fates of this cartilage, examining the control of Meckel's cartilage patterning, initiation and maturation. Importantly, human disorders and mouse models with disrupted Meckel's cartilage development are highlighted, in order to understand how changes in this cartilage impact on later development of the dentary and the craniofacial complex as a whole. Finally, the relative roles of tissue interactions, apoptosis, autophagy, macrophages and clast cells in the removal process are discussed. Meckel's cartilage is a unique and enigmatic structure, the development and function of which is starting to be understood but many interesting questions still remain.
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Affiliation(s)
- Eva Svandova
- Institute of Animal Physiology and Genetics, Academy of Sciences, Brno, Czechia
| | - Neal Anthwal
- Centre for Craniofacial and Regenerative Biology, King’s College London, Guy’s Hospital, London, United Kingdom
| | - Abigail S. Tucker
- Centre for Craniofacial and Regenerative Biology, King’s College London, Guy’s Hospital, London, United Kingdom
| | - Eva Matalova
- Institute of Animal Physiology and Genetics, Academy of Sciences, Brno, Czechia
- Department of Physiology, University of Veterinary and Pharmaceutical Sciences, Brno, Czechia
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Brăescu R, Săvinescu SD, Tatarciuc MS, Zetu IN, Giuşcă SE, Căruntu ID. Pointing on the early stages of maxillary bone and tooth development - histological findings. ROMANIAN JOURNAL OF MORPHOLOGY AND EMBRYOLOGY = REVUE ROUMAINE DE MORPHOLOGIE ET EMBRYOLOGIE 2020; 61:167-174. [PMID: 32747908 PMCID: PMC7728135 DOI: 10.47162/rjme.61.1.19] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Accepted: 07/21/2020] [Indexed: 11/17/2022]
Abstract
Although the morphological stages of tooth development, in parallel with maxillary bone construction, are known for decades, the intimate mechanisms of early development of the oral cavity structures and tooth's proper and associated tissues are still incompletely elucidated. Nowadays, the research in embryology was shifted from the morphological to the molecular and genetic approach. This new approach is accomplished by using in vivo and in vitro experimental studies performed on animal models and cell lines. The interest in the knowledge of these events at gene and molecular level is still current, aiming to sustain the progress in the endorsement of novel regenerative and restorative therapies. However, the morphological standpoint maintains its interest, because the extrapolation of the results of experimental studies in humans requires a strong confirmation. Within this context, our work aims to analyze the histological characteristics of the maxillary bone and integrated tooth germs during the early stages of embryonic development. The study group consisted in mandible fragments obtained by dissection of the cephalic extremities collected from fetuses aged from 10 to 24 weeks, after medical or spontaneous abortions. The tissue specimens were processed for the histological exam. The histoarchitectonic traits of the initial stages of mandibular bone tissue and tooth development were assessed. The results revealed the dynamics of the ossification stages, from stages of early-dispersed intramembranous ossification to the organization of the dental alveoli, incorporated step-by-step in the maxillary body, and the simultaneous presence of tooth germs with different sizes and shapes, in accordance with the development stage. Our study complements the existing data regarding the embryonic period, bringing an important contribution for the enlargement of existing morphological, visual information for maxillary bone and tooth development.
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Affiliation(s)
- Radu Brăescu
- Department of Morphofunctional Sciences I - Pathology, Grigore T. Popa University of Medicine and Pharmacy, Iaşi, Romania; ,
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Maldonado E, López Y, Herrera M, Martínez-Sanz E, Martínez-Álvarez C, Pérez-Miguelsanz J. Craniofacial structure alterations of foetuses from folic acid deficient pregnant mice. Ann Anat 2018; 218:59-68. [DOI: 10.1016/j.aanat.2018.02.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Revised: 01/17/2018] [Accepted: 02/06/2018] [Indexed: 12/18/2022]
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8
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Chondral ossification centers next to dental primordia in the human mandible: A study of the prenatal development ranging between 68 to 270mm CRL. Ann Anat 2016; 208:49-57. [PMID: 27497714 DOI: 10.1016/j.aanat.2016.07.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2016] [Revised: 06/21/2016] [Accepted: 07/04/2016] [Indexed: 11/23/2022]
Abstract
The human mandible is said to arise from desmal ossification, which, however, is not true for the entire body of the mandible: Meckel's cartilage itself is prone to ossification, at least its anterior part in the canine and incisor region. Also, within the coronoid and in the condylar processes there are cartilaginous cores, which eventually undergo ossification. Furthermore, there are a number of additional single cartilaginous islets arising in fetuses of 95mm CRL and more. They are located predominantly within the bone at the buccal sides of the brims of the dental compartments, mostly in the gussets between the dental primordia. They become wedge-shaped or elongated with a diameter of around 150-500μm and were also found in older stages up to 225mm CRL, which was the oldest specimen used in this study. This report is intended to visualize these single cartilaginous islets histologically and in 3-D reconstructions in stereoscopic images. Although some singular cartilaginous tissue within the mandible may be remains of the decaying Meckel's cartilage, our 3-D reconstructions clearly show that the aforementioned cartilaginous islets are independent thereof, as can be derived from their separate locations within the mandibular bone. The reasons that lead to these cartilaginous formations have remained unknown so far.
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9
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Nayak SS, Nayak VS. A Rare Case of Mandibular Exostoses and its Review. J Clin Diagn Res 2016; 10:AJ01-2. [PMID: 26894053 DOI: 10.7860/jcdr/2016/17305.7159] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2015] [Accepted: 12/17/2015] [Indexed: 11/24/2022]
Abstract
Mandibular exostosis is a type of bony prominence caused due to hyperostosis in the mandibular bone. They are benign, broad-based surface masses on the outer or facial aspect of the jaw bones; slowly enlarge over the years to form the bulky masses. During the period between the 10th to 13th week of intrauterine life, changes in the structure of the Meckel's cartilage and the protrusion of the medial lamina of the mandible onto the cartilage can result in the formation of such exostosis. We discuss here a very rare case of a 49-year-old male, in which the buccal exostoses formed underwent changes in size and shape due to certain factors, resulting in a bony bar formation in the mandibular anterior region.
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Affiliation(s)
- Sunil S Nayak
- Assistant Professor, Department of Oral and Maxillofacial Surgery, Srinivas Institute of Dental Sciences , Mukka, Mangalore, India
| | - Vanishri S Nayak
- Senior Grade Lecturer, Department of Anatomy, Kasturba Medical College, Manipal University , Manipal, India
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Guan X, Song Y, Ott J, Zhang Y, Li C, Xin T, Li Z, Gan Y, Li J, Zhou S, Zhou Y. The ADAMTS1 Gene Is Associated with Familial Mandibular Prognathism. J Dent Res 2015; 94:1196-201. [PMID: 26124221 DOI: 10.1177/0022034515589957] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Mandibular prognathism is a facial skeletal malocclusion. Until now, the genetic mechanism has been unclear. The goal of this study was to identify candidate genes or genomic regions directly associated with mandibular prognathism development, by employing whole genome sequencing. A large Chinese family was recruited, composed of 9 affected and 12 unaffected individuals, and the inheritance pattern of this family tends to be autosomal dominant. A single-nucleotide missense mutation in the ADAMTS1 gene (c. 742I>T) was found to segregate in the family, given that the affected individuals must be heterozygous for the mutation. For mutation validation, we screened this candidate mutation and 15 tag single-nucleotide polymorphisms in the coding sequence of ADAMTS1 among 230 unrelated cases and 196 unrelated controls using Sequenom Massarray and found that 3 in 230 cases carried this mutation and none of the controls did. Final results suggested that 2 single-nucleotide polymorphisms (rs2738, rs229038) of ADAMTS1 were significantly associated with mandibular prognathism.
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Affiliation(s)
- X Guan
- Department of Orthodontics, Peking University School and Hospital of Stomatology, Beijing, P.R. China
| | - Y Song
- Department of Orthodontics, Peking University School and Hospital of Stomatology, Beijing, P.R. China
| | - J Ott
- Department of Laboratory of Statistical Genetics, Institute of Psychology, Chinese Academy of Sciences, Beijing, P.R. China, and Rockefeller University, New York, NY, USA
| | - Y Zhang
- Department of Orthodontics, Peking University School and Hospital of Stomatology, Beijing, P.R. China
| | - C Li
- Department of Orthodontics, Peking University School and Hospital of Stomatology, Beijing, P.R. China
| | - T Xin
- Department of Orthodontics, Peking University School and Hospital of Stomatology, Beijing, P.R. China
| | - Z Li
- Department of Oral and Maxillofacial Surgery, Peking University School and Hospital of Stomatology. Beijing, P.R. China
| | - Y Gan
- Department of Laboratory of Molecular Biology and Center for TMD and Orofacial Pain, Peking University School and Hospital of Stomatology. Beijing, P.R. China
| | - J Li
- Department of Orthodontics, Peking University School and Hospital of Stomatology, Beijing, P.R. China
| | - S Zhou
- Department of Orthodontics, Peking University School and Hospital of Stomatology, Beijing, P.R. China
| | - Y Zhou
- Department of Orthodontics, Center for Craniofacial Stem Cell Research, Regeneration, and Translational Medicine, Peking University School and Hospital of Stomatology, Beijing, P.R. China
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Tan TY, Kilpatrick N, Farlie PG. Developmental and genetic perspectives on Pierre Robin sequence. AMERICAN JOURNAL OF MEDICAL GENETICS PART C-SEMINARS IN MEDICAL GENETICS 2013; 163C:295-305. [PMID: 24127256 DOI: 10.1002/ajmg.c.31374] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Pierre Robin sequence (PRS) is a craniofacial anomaly comprising mandibular hypoplasia, cleft secondary palate and glossoptosis leading to life-threatening obstructive apnea and feeding difficulties during the neonatal period. The respiratory issues require careful management and in severe cases may require extended stays in neonatal intensive care units and surgical intervention such as lengthening the lower jaw or tracheotomy to relieve airway obstruction. These feeding and respiratory complications frequently continue well into childhood, affecting not only growth and development but also impacting on long term educational attainment. The diagnosis of PRS depends on readily recognizable clinical features but the phenotypic similarity of many PRS individuals conceals considerable etiological heterogeneity. Defects in the growth of the mandible sit at the core of PRS and the natural history of PRS can be classified into two major streams: primary defects of mandibular outgrowth and elongation and issues that are external to the mandibular skeleton but that secondarily impact on its growth. These altered developmental trajectories appear to be driven by a range of influences including defects in cartilage growth, neuromuscular function and fetal constraint. Various genetic and cytogenetic associations have been made with PRS and the diversity of these associations highlights the fact that there are numerous ways to arrive at this common phenotypic endpoint.
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12
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Starbuck JM, Cole TM, Reeves RH, Richtsmeier JT. Trisomy 21 and facial developmental instability. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2013; 151:49-57. [PMID: 23505010 DOI: 10.1002/ajpa.22255] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2012] [Accepted: 02/06/2013] [Indexed: 01/03/2023]
Abstract
The most common live-born human aneuploidy is trisomy 21, which causes Down syndrome (DS). Dosage imbalance of genes on chromosome 21 (Hsa21) affects complex gene-regulatory interactions and alters development to produce a wide range of phenotypes, including characteristic facial dysmorphology. Little is known about how trisomy 21 alters craniofacial morphogenesis to create this characteristic appearance. Proponents of the "amplified developmental instability" hypothesis argue that trisomy 21 causes a generalized genetic imbalance that disrupts evolutionarily conserved developmental pathways by decreasing developmental homeostasis and precision throughout development. Based on this model, we test the hypothesis that DS faces exhibit increased developmental instability relative to euploid individuals. Developmental instability was assessed by a statistical analysis of fluctuating asymmetry. We compared the magnitude and patterns of fluctuating asymmetry among siblings using three-dimensional coordinate locations of 20 anatomic landmarks collected from facial surface reconstructions in four age-matched samples ranging from 4 to 12 years: (1) DS individuals (n = 55); (2) biological siblings of DS individuals (n = 55); 3) and 4) two samples of typically developing individuals (n = 55 for each sample), who are euploid siblings and age-matched to the DS individuals and their euploid siblings (samples 1 and 2). Identification in the DS sample of facial prominences exhibiting increased fluctuating asymmetry during facial morphogenesis provides evidence for increased developmental instability in DS faces. We found the highest developmental instability in facial structures derived from the mandibular prominence and lowest in facial regions derived from the frontal prominence.
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Affiliation(s)
- John M Starbuck
- Department of Anthropology, The Pennsylvania State University, University Park, PA 16802, USA
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Anthwal N, Joshi L, Tucker AS. Evolution of the mammalian middle ear and jaw: adaptations and novel structures. J Anat 2012; 222:147-60. [PMID: 22686855 DOI: 10.1111/j.1469-7580.2012.01526.x] [Citation(s) in RCA: 92] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Having three ossicles in the middle ear is one of the defining features of mammals. All reptiles and birds have only one middle ear ossicle, the stapes or columella. How these two additional ossicles came to reside and function in the middle ear of mammals has been studied for the last 200 years and represents one of the classic example of how structures can change during evolution to function in new and novel ways. From fossil data, comparative anatomy and developmental biology it is now clear that the two new bones in the mammalian middle ear, the malleus and incus, are homologous to the quadrate and articular, which form the articulation for the upper and lower jaws in non-mammalian jawed vertebrates. The incorporation of the primary jaw joint into the mammalian middle ear was only possible due to the evolution of a new way to articulate the upper and lower jaws, with the formation of the dentary-squamosal joint, or TMJ in humans. The evolution of the three-ossicle ear in mammals is thus intricately connected with the evolution of a novel jaw joint, the two structures evolving together to create the distinctive mammalian skull.
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Affiliation(s)
- Neal Anthwal
- Division of Developmental Neurobiology, MRC National Institute for Medical Research, London, UK
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Tan TY, Farlie PG. Rare syndromes of the head and face-Pierre Robin sequence. WILEY INTERDISCIPLINARY REVIEWS-DEVELOPMENTAL BIOLOGY 2012; 2:369-77. [PMID: 23799581 DOI: 10.1002/wdev.69] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Pierre Robin sequence (PRS) is an association of clinical features consisting of mandibular hypoplasia, cleft secondary palate, and glossoptosis leading to obstructive apnea and feeding difficulties. PRS can occur as an isolated condition or can be found in association with a range of other features in a number of conditions including Treacher collins and Stickler syndromes. The frequent association of the PRS triad suggests a common underlying developmental mechanism which impacts on each of these tissues. Isolated PRS is typically sporadic but when familial usually exhibits autosomal dominant inheritance. The term PRS is applied on the basis of the pattern of malformation rather than etiology and growing evidence indicates that the initiating genetic lesion is variable. Various chromosomal anomalies have been associated with PRS including loci on chromosomes 2, 4, and 17. Associations with genes including SOX9, a number of collagen genes and work with animal models suggest the phenotype derives from a cartilage defect during early facial growth. However, alternative theories have been proposed and these highlight the difficulty of characterising congenital anomalies of craniofacial development in which multiple etiologies can result in very similar phenotypes.
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Affiliation(s)
- Tiong Yang Tan
- Murdoch Childrens Research Institute, Royal Children's Hospital, Parkville, Australia
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