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Concept: Cleidocranial dysostosis

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BACKGROUND: Cleidocranial dysplasia (CCD) is a rare congenital autosomal dominant skeletal disorder. The disorder is caused by heterozygosity of mutations in human RUNX2, which is present on the short arm of chromosome 6p21. The incidence of CCD is one per million births. CCD appears spontaneously with no apparent genetic cause in approximately 40% of affected patients, and one in three patients has unaffected parents. The most prevalent features associated with CCD are aplastic or hypoplastic clavicles, supernumerary teeth, failed eruption of permanent teeth, and a hypoplastic maxilla. CASE PRESENTATION: A 13-year-old Caucasian boy presented with a chief complaint of delayed eruption of the permanent anterior teeth. The patient was subsequently diagnosed with CCD based on the clinical examination, panoramic X-ray, anterior-posterior and lateral cephalogram, and chest radiograph findings. The details of this case are herein reported because of the extremely low incidence of this disorder. CONCLUSIONS: CCD is of clinical importance in dentistry and medicine because it affects the bones and teeth and is characterized by many changes in skeletal patterning and growth. Particularly in dentistry, CCD is of great clinical significance because is associated with delayed ossification of the skull sutures, delayed exfoliation of the primary teeth, lack of permanent teeth eruption, multiple supernumerary teeth, and morphological abnormalities of the maxilla and mandible. Patients with CCD seek treatment mainly for dental problems. Knowledge of the pathogenesis, clinical characteristics, and diagnostic tools of CCD will enable clinicians to render the appropriate treatment to improve function and aesthetics. Early diagnosis of CCD is crucial for timely initiation of an appropriate treatment approach.

Concepts: Medical statistics, Dental anatomy, Chromosome, Teeth, Permanent teeth, Cleidocranial dysostosis, Hyperdontia, Medical terms

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This clinical report describes the oral rehabilitation with implant-supported fixed dental prostheses in the maxilla and mandible of a patient with cleidocranial dysplasia. Cone-beam computed tomography and a tilted implant protocol in the mandible helped to establish a conservative approach for bone preservation, prevent surgical complications, enable proper implant positioning to avoid anatomic structures, and support the fixed dental prostheses.

Concepts: Dental implant, Cleidocranial dysostosis, Medicine, Prosthetics, Physician, Anatomy

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A Thai mother and her two daughters were affected with tricho-rhino-phalangeal syndrome type I. The daughters had 15 and 18 supernumerary teeth, respectively. The mother had normal dentition. Mutation analysis of TRPS1 showed a novel heterozygous c.3809_3811delACTinsCATGTTGTG mutation in all. This mutation is predicted to cause amino acid changes in the Ikaros-like zinc finger domain near the C-terminal end of TRPS1, which is important for repressive protein function. The results of our study and the comprehensive review of the literature show that pathways of forming supernumerary teeth appear to involve APC and RUNX2, the genes responsible for familial adenomatous polyposis syndrome and cleidocranial dysplasia, respectively. The final pathway resulting in supernumerary teeth seems to involve Wnt, a morphogen active during many stages of development. © 2016 Wiley Periodicals, Inc.

Concepts: Family, Familial adenomatous polyposis, Protein structure, Acid, Amino acid, Cleidocranial dysostosis, Hyperdontia, Protein

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Wormian bones are independent ossification centers found within cranial sutures or fontanelles. Though common in adult populations, their presence in children can be associated with several conditions such as osteogenesis imperfecta, hypothyroidism, pyknodysostosis, cleidocranial dysostosis, rickets, and acrocallosal syndrome. These conditions encompass a large range of clinical features but there has only been 1 other reported patient of exomphalos occurring concurrently with these ossicles. The authors present the case of a child with an anterior fontanellar Wormian bone, dysmorphic facial features, and exomphalos major born to unaffected parents. The pattern of features seen in this child did not closely match any condition commonly associated with Wormian bones. The only other reported case of both Wormian bone and exomphalos was in a child with acrocallosal syndrome who presented with more severe dysmorphic features than seen here. It is possible that this patient represents a previously unknown association between acrocallosal syndrome and exomphalos or a less severe variant of the condition. Conversely, this patient may possibly illustrate a newly discovered association between Wormian bones, facial dysmorphism, and midline abdominal defects.

Concepts: Osteogenesis imperfecta, Cleidocranial dysostosis, Skull, Fontanelle

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  The aim of this article is to publish a literature review and report on a new case of cleidocranial dysplasia syndrome with 6p21.1-p12.3 microdeletion.

Concepts: Myelodysplastic syndrome, Writing, Cleidocranial dysostosis, Genetic disorders

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While most supernumerary teeth are idiopathic, they can be associated with a number of Mendelian syndromes. However, this can also be a coincidental finding, since supernumerary teeth occur in 6% or more of the normal population. To better define this relationship, we analyzed the evidence for specific associations. We excluded conditions with a single affected patient reported, supernumerary teeth adjacent to clefts or other forms of alveolar disruption (as secondary rather than primary findings), and natal teeth, which can involve premature eruption of a normal tooth. Since, the cause of supernumerary teeth shows considerable heterogeneity, certain findings are less likely to be coincidental, such as five or more supernumerary teeth in a single patient, or locations outside of the premaxilla. We found only eight genetic syndromes with strong evidence for an association: cleidocranial dysplasia; familial adenomatous polyposis; trichorhinophalangeal syndrome, type I; Rubinstein-Taybi syndrome; Nance-Horan syndrome; Opitz BBB/G syndrome; oculofaciocardiodental syndrome; and autosomal dominant Robinow syndrome. There is also suggestive evidence of an association with two uncommon disorders, Kreiborg-Pakistani syndrome (craniosynostosis and dental anomalies), and insulin-resistant diabetes mellitus with acanthosisnigricans. An association of a Mendelian disorder with a low frequency manifestation of supernumerary teeth is difficult to exclude without large numbers, but several commonly cited syndromes lacked evidence for clear association, including Hallermann-Streiff syndrome, Fabry disease, Ehlers-Danlos syndrome, Apert and Crouzon syndromes, Zimmermann-Laband syndrome, and Ellis-van Creveld syndrome. © 2016 Wiley Periodicals, Inc.

Concepts: Cleidocranial dysostosis, Teeth, Hypermobility, The Canon of Medicine, Hyperdontia, Diabetes mellitus, Syndromes, Genetic disorders

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Cleidocranial dysplasia (CCD) is a rare genetic disorder of bone, characterised by hypoplastic/aplastic clavicles, delayed closure of fontanelles and sutures of the cranium and dental abnormalities. We describe a novel frameshift pathogenic variation-c.470dupT (p.M157Ifs*4, NM_001024630) in the runt-related transcription factor 2 (RUNX2) gene-that adds to the spectrum of mutations in this gene. The current case also illustrates the clinical and radiological findings in an adult with CCD.

Concepts: Gene, Cleidocranial dysostosis, Gene expression, Cancer, Transcription, Fontanelle, DNA, Genetics

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Loss-of-function mutations of RUNX2 are responsible for cleidocranial dysplasia, an autosomal dominant disorder characterized by delayed closure of cranial sutures, aplastic or hypoplastic clavicles, moderate short stature and supernumerary teeth. By contrast, an increased gene dosage is expected for duplication of the entire RUNX2 sequence and thus, a phenotype different from cleidocranial dysplasia. To date, two cousins with a duplication including the entire RUNX2 sequence in addition to MIR586, CLIC5 and the 5' half of SUPT3H have been reported. These patients presented with metopic synostosis and hypodontia. Here, we report on a family with an affected mother and three affected children. The four patients carried a 285 kb duplication identified by array comparative genomic hybridization. The duplication includes the entire sequence of RUNX2 and the 5' half of SUPT3H. We confirmed the duplication by real-time quantitative PCR in the four patients. Two children presented with the association of metopic craniosynostosis and oligo/hypodontia previously described, confirming the phenotype caused by RUNX2 duplication. Interestingly, the mother and one child had isolated hypodontia without craniosynostosis, broadening the phenotype observed in patients with such duplications. © 2015 Wiley Periodicals, Inc.

Concepts: Haploinsufficiency, Cleidocranial dysostosis, Gene duplication, DNA, Gene, Evolution, Hyperdontia, Mutation

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Cleidocranial dysplasia (CCD; MIM 119600) is an autosomal dominant skeletal dysplasia characterised by hypopalstic and/or aplastic clavicles, midface hypoplasia, absent or delayed closure of cranial sutures, moderately short stature, delayed eruption of permanent dentition and supernumerary teeth. The molecular pathogenesis can be explained in about two-thirds of CCD patients by haploinsufficiency of the RUNX2 gene. In our current study, we identified a novel and rare variant of the RUNX2 gene (c.181_189dupGCGGCGGCT) in a Japanese patient with phenotypic features of CCD. The insertion led an alanine tripeptide expansion (+3Ala) in the polyalanine tract. To date, a RUNX2 variant with alanine decapeptide expansion (+10Ala) is the only example of a causative variant of RUNX2 with polyalanine tract expansion to be reported, whilst RUNX2 (+1Ala) has been isolated from the healthy population. Thus, precise analyses of the RUNX2 (+3Ala) variant were needed to clarify whether the tripeptide expanded RUNX2 is a second disease-causing mutant with alanine tract expansion. We therefore investigated the biochemical properties of the mutant RUNX2 (+3Ala), which contains 20 alanine residues in the polyalanine tract. When transfected in COS7 cells, RUNX2 (+3Ala) formed intracellular ubiquitinated aggregates after 24h, and exerted a dominant negative effect in vitro. At 24h after gene transfection, whereas slight reduction was observed in RUNX2 (+10Ala), all of these mutants significantly activated osteoblast-specific element-2, a cis-acting sequence in the promoter of the RUNX2 target gene osteocalcin. The aggregation growth of RUNX2 (+3Ala) was clearly lower and slower than that of RUNX2 (+10Ala). Furthermore, we investigated several other RUNX2 variants with various alanine tract lengths, and found that the threshold for aggregation may be RUNX2 (+3Ala). We conclude that RUNX2 (+3Ala) is the cause of CCD in our current case, and that the accumulation of intracellular aggregates in vitro is related to the length of the alanine tract.

Concepts: Transfection, Haploinsufficiency, Mutant, Gene, Hyperdontia, Cleidocranial dysostosis, Mutation, Molecular biology

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Cleidocranial dysplasia (CD) is an autosomal dominant syndrome which is characterized by several skeletal malformations such as non-closed fontanelles, skeletal abnormalities of the maxilla and mandible and absence of clavicles. Mid-facial hypoplasia and mandibular prognathism are mostly seen jaw abnormalities in CD. In this study, the combined orthodontic-surgical treatment of a patient with CD with class III malocclusion and multiple unerupted primary and deciduous teeth is presented.

Concepts: Class III railroad, Deciduous teeth, Orthodontics, Fontanelle, Prognathism, Cleidocranial dysostosis, Mandible, Malocclusion