Related Experiment Video
Updated: Dec 8, 2025
Comparative Lesions Analysis Through a Targeted Sequencing Approach
Published on: November 5, 2019
Targeted Next-Generation Sequencing and Allele-Specific Quantitative PCR of Laser Capture Microdissected Samples
Bruna Pizziolo Coura1, Vanessa Fátima Bernardes1, Sílvia Ferreira de Sousa2
1Department of Pathology, Biological Sciences Institute, Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, Brazil.
Abstract:
The molecular pathogenesis of mixed odontogenic tumors has not been established, and understanding their genetic basis could refine their classification and help define molecular markers for diagnostic purposes. Potentially pathogenic mutations in the component tissues of 28 cases of mixed odontogenic tumors were assessed. Laser capture microdissected tissue from 10 ameloblastic fibromas (AF), 4 ameloblastic fibrodentinomas (AFD), 6 ameloblastic fibro-odontomas (AFO), 3 ameloblastic fibrosarcomas (AFS), and 5 odontomas (OD) were screened by next-generation sequencing and results confirmed by TaqMan allele-specific quantitative PCR. BRAF p.V600E mutation in the mesenchymal component was shown in 4 of 10 AF (40%), 2 of 4 AFD (50%), 2 of 6 AFO (33%), and 2 of 3 AFS (67%), whereas all 5 OD were wild type for BRAF p.V600E. Mutation in the epithelial component was only observed in one AF and one AFO. One AFS contained an area of benign AF, and the mesenchymal component of both (AFS and AF) contained BRAF p.V600E, supporting the concept of malignant progression from a benign AF precursor. KDR, TP53, KIT, and PIK3CA single-nucleotide polymorphisms are reported. In conclusion, AF, AFD, AFO, and AFS show BRAF p.V600E in their mesenchymal component, unlike OD, which are BRAF wild type, suggesting that at least a subset of AF, AFD, and AFO are molecularly distinct from OD, and may represent distinct entities and be neoplastic.
Insights
Mixed odontogenic tumors like ameloblastic fibromas (AF) and ameloblastic fibrosarcomas (AFS) often harbor BRAF p.V600E mutations, unlike odontomas (OD). This genetic difference suggests distinct molecular pathways and aids in classifying these tumors.
Area of Science:
- Oral Pathology
- Molecular Oncology
- Genetics
Background:
- The molecular pathogenesis of mixed odontogenic tumors remains unclear.
- Understanding their genetic basis is crucial for refining classification and identifying diagnostic markers.
Purpose of the Study:
- To investigate potentially pathogenic mutations in the component tissues of various mixed odontogenic tumors.
- To determine if genetic differences can distinguish between tumor types and support classification.
Main Methods:
- Laser capture microdissection of 28 mixed odontogenic tumors (AF, AFD, AFO, AFS, OD).
- Next-generation sequencing and TaqMan quantitative PCR to screen for mutations, including BRAF p.V600E.
Main Results:
- BRAF p.V600E mutations were identified in the mesenchymal component of ameloblastic fibromas (40%), ameloblastic fibrodentinomas (50%), ameloblastic fibro-odontomas (33%), and ameloblastic fibrosarcomas (67%).
- Odontomas were consistently BRAF p.V600E wild type.
- A case of ameloblastic fibrosarcoma showed a benign ameloblastic fibroma component, both harboring BRAF p.V600E, suggesting malignant progression.
Conclusions:
- Ameloblastic fibromas, fibrodentinomas, fibro-odontomas, and fibrosarcomas exhibit BRAF p.V600E mutations in their mesenchymal component, distinguishing them from BRAF wild-type odontomas.
- These genetic findings suggest that a subset of these tumors are molecularly distinct from odontomas and may represent separate neoplastic entities.
