Cleidocranial Dysplasia: A Clinico-radiographic Spectrum with Differential Diagnosis

Clinical and neuroimaging review of triplet repeat diseases

Triplet repeat diseases (TRDs) refer to a group of diseases caused by three nucleotide repeats elongated beyond a pathologic threshold. TRDs are divided into the following four groups depending on the pathomechanisms, although the pathomechanisms of several diseases remain unelucidated: polyglutamine disorders, caused by a pathologic repeat expansion of CAG (coding the amino acid glutamine) located within the exon; loss-of-function repeat disorders, characterized by the common feature of a loss of function of the gene within which they occur; RNA gain-of-function disorders, involving the production of a toxic RNA species; and polyalanine disorders, caused by a pathologic repeat expansion of GCN (coding the amino acid alanine) located within the exon. Many of these TRDs manifest through neurologic symptoms; moreover, neuroimaging, especially brain magnetic resonance imaging, plays a pivotal role in the detection of abnormalities, differentiation, and management of TRDs. In this article, we reviewed the clinical and neuroimaging features of TRDs. An early diagnosis of TRDs through clinical and imaging approaches is important and may contribute to appropriate medical intervention for patients and their families.

Identification of a Novel Splice Site Mutation in RUNX2 Gene in a Family with Rare Autosomal Dominant Cleidocranial Dysplasia

Background:

Pathogenic variants of RUNX2, a gene that encodes an osteoblast-specific transcription factor, have been shown as the cause of CCD, which is a rare hereditary skeletal and dental disorder with dominant mode of inheritance and a broad range of clinical variability. Due to the relative lack of clinical complications resulting in CCD, the medical diagnosis of this disorder is challenging, which leaves it underdiagnosed.

Methods:

In this study, nine healthy and affected members of an Iranian family were investigated. PCR and sequencing of all exons and exon-intron boundaries of RUNX2 (NM_001024630) gene was performed on proband. Co-segregation analysis was conducted in the other family members for the identified variant. Additionally, a cohort of 100 Iranian ethnicity-matched healthy controls was screened by ARMS-PCR method.

Results:

The novel splice site variant (c.860-2A>G), which was identified in the intron 6 of RUNX2 gene, co-segregated with the disease in the family, and it was absent in healthy controls. Pathogenicity of this variant was determined by several software, including HSF, which predicts the formation or disruption of splice donor sites, splice acceptor sites, exonic splicing silencer sites, and exonic splicing enhancer sites. In silico analysis predicted this novel variant to be disease causing.

Conclusion:

The identified variant is predicted to have an effect on splicing, which leads to exon skipping and producing a truncated protein via introducing a premature stop codon.

Cleidocranial dysostosis: a case report with clinical illustration

Cleidocranial Dysostosis or Dysplasia (CCD) is an infrequent clinical condition, with an autosomal dominant hereditary mode of inheritance. Triad lesions: multiple supernumerary teeth, partial or complete absence of the clavicles and open sagittal sutures and fontanelles. Nine-year-old female patient comes to our service for outpatient consultation with the main complaint of upper limbs mobility restriction with shoulders hypermotility. The chest X-ray showed partial absence of the clavicles and a cone-shaped thorax. The diagnosis of CCD was performed. Treatment of these patients requires a multidisciplinary approach which includes orthopaedic and dental corrections. The premature diagnosis allows a proper orientation for the treatment, offering a better life quality for the patient.

Imaging studies used as aid in the diagnosis of cleidocranial dysplasia. A review

Cleidocranial dysplasia (CCD), also known as Marie-Sainton syndrome, is a rare disorder of autosomal dominant type that presents specific characteristics at the skeletal and dental level. The diagnosis of CCD is based on clinical and radiographic findings. Panoramic, cephalometric and anterior poster radiographs have been used for its diagnosis in dentistry. However, these radiological techniques have limitations, and advances in technology with new imaging studies such as magnetic resonance imaging (MRI) and ultrasound have emerged, contributing to the diagnosis of CCD. Therefore, the aim of this review was to identify and describe current imaging studies that contribute to both the diagnosis and adequate and efficient treatment planning of CCD, and describe the clinical and radiographic characteristics of patients with this syndrome.

Reconstruction Using Free Vascularized Fibular Grafts after Wide Resection of Humerus Chondrosarcoma in a Patient with Cleidocranial Dysplasia

Cleidocranial dysplasia is characterized by hypoplasia of the clavicles, unerupted teeth, narrow pelvis, short stature, and craniofacial malformations. A cause of this skeletal dysplasia is heterozygous mutations of the runt-related transcription factor 2 gene (Runx2), a master regulator for bone and cartilage development. Chondrosarcoma is a primary malignant bone tumor that is usually treated by wide resection surgery. This report shows a case of a 25-year-old female patient with cleidocranial dysplasia who was affected with chondrosarcoma of the left humerus. We performed wide resection of the tumor and reconstruction of the large bone defect of the humerus using free vascularized fibular grafts. The patient preserved the hand function and activity of daily life as the same level as preoperative condition more than five years after the surgery.

Clinical and radiological findings in a severe case of cleidocranial dysplasia

Cleidocranial dysplasia (CCD) is a rare congenital autosomal dominant condition, causing hypoplasia of the clavicle, abnormal formation of teeth, skeletal and craniofacial bones. CCD is caused by the mutation of RUNX2/CBFA1 present in the short arm of chromosome 6 at position 21.1, a transcription factor essential for the formation of teeth, cartilage and bone. Patients with CCD show the classical features of excessive mobility of the shoulder bone, lack of resorption of the deciduous teeth, failure to erupt permanent teeth, multiple impacted and supernumerary teeth, and open fontanelle and sutures of the skull. In this article we report a case of CCD in a 16-year-old male patient, with an aim to highlight the clinical, radiological and recommended treatment guidelines.