Related Experiment Videos
Mutation analysis of core binding factor A1 in patients with cleidocranial dysplasia
I Quack1, B Vonderstrass, M Stock
1Department of Hematology, University of Freiburg Medical Center, Freiburg, Germany.
Insights
Mutations in the CBFA1 gene cause cleidocranial dysplasia (CCD), a disorder affecting bone and teeth development. This study identifies new mutations and expands the known spectrum of CCD phenotypes, including exclusive dental issues and adult bone maintenance roles.
Area of Science:
- Genetics
- Molecular Biology
- Skeletal Dysplasias
Background:
- Cleidocranial dysplasia (CCD) is an inherited disorder affecting skeletal development, characterized by specific craniofacial and clavicular anomalies.
- Recent research linked CCD to mutations in the CBFA1 gene, a key transcription factor involved in bone development.
Purpose of the Study:
- To analyze the CBFA1 gene in a cohort of 42 unrelated patients with CCD.
- To identify specific mutations and understand their correlation with the clinical phenotype of CCD.
- To investigate the functional impact of identified mutations on CBFA1 protein activity.
Main Methods:
- Genetic analysis of the CBFA1 gene in 42 CCD patients.
- Mutation screening including sequencing of the coding region.
- In vitro studies using green fluorescent protein (GFP) fusion to assess protein localization.
Main Results:
- Mutations in the CBFA1 gene were identified in 18 out of 42 patients.
- A variety of mutations were found, including frameshift, nonsense, and missense mutations, with a notable cluster at arginine 225 (R225).
- R225 mutations were shown to impair nuclear accumulation of CBFA1 protein, suggesting a critical role for this residue.
- The study identified novel phenotypic presentations, including isolated dental anomalies and evidence of CBFA1's role in adult bone maintenance.
Conclusions:
- Mutations in the CBFA1 gene are a primary cause of cleidocranial dysplasia, often acting through haploinsufficiency.
- The CBFA1 gene plays a crucial role not only in skeletal development but also in maintaining adult bone integrity.
- The phenotypic spectrum of CCD is broader than previously recognized, encompassing isolated dental abnormalities.
Abstract:
Cleidocranial dysplasia (CCD) is a dominantly inherited disorder characterized by patent fontanelles, wide cranial sutures, hypoplasia of clavicles, short stature, supernumerary teeth, and other skeletal anomalies. We recently demonstrated that mutations in the transcription factor CBFA1, on chromosome 6p21, are associated with CCD. We have now analyzed the CBFA1 gene in 42 unrelated patients with CCD. In 18 patients, mutations were detected in the coding region of the CBFA1 gene, including 8 frameshift, 2 nonsense, and 9 missense mutations, as well as 2 novel polymorphisms. A cluster of missense mutations at arginine 225 (R225) identifies this residue as crucial for CBFA1 function. In vitro green fluorescent protein fusion studies show that R225 mutations interfere with nuclear accumulation of CBFA1 protein. There is no phenotypic difference between patients with deletions or frameshifts and those with other intragenic mutations, suggesting that CCD is generally caused by haploinsufficiency. However, we were able to extend the CCD phenotypic spectrum. A missense mutation identified in one family with supernumerary teeth and a radiologically normal skeleton indicates that mutations in CBFA1 can be associated exclusively with a dental phenotype. In addition, one patient with severe CCD and a frameshift mutation in codon 402 had osteoporosis leading to recurrent bone fractures and scoliosis, providing first evidence that CBFA1 may help maintain adult bone, in addition to its function in bone development.