Genome sequencing reveals molecular subgroups in oral epithelial dysplasia.

This study aimed to analyze the molecular characteristics of oral epithelial dysplasia (OED), highlighting the pathways and variants of genes that are frequently mutated in oral squamous cell carcinoma (OSCC) and other cancers. Ten archival OED cases were retrieved for retrospective clinicopathological analysis and exome sequencing. Comparative genomic analysis was performed between high-grade dysplasia (HGD) and low-grade dysplasia (LGD), focusing on 57 well-known cancer genes, of which 10 were previously described as the most mutated in OSCC. HGD cases had significantly more variants; however, a similar mutational landscape to OSCC was observed in both groups. CASP8+FAT1/HRAS, TP53, and miscellaneous molecular signatures were also present. FAT1 is the gene that is most affected by pathogenic variants. Hierarchical divisive clustering showed division between the two groups: "HGD-like cluster" with 4HGD and 2LGD and "LGD-like cluster" with 4 LGD. MLL4 pathogenic variants were exclusively in the "LGD-like cluster". TP53 was affected in one case of HGD; however, its pathway was usually altered. We describe new insights into the genetic basis of epithelial malignant transformation by genomic analysis, highlighting those associated with FAT1 and TP53. Some LGDs presented a similar mutational landscape to HGD after cluster analysis. Perhaps molecular alterations have not yet been reflected in histomorphology. The relative risk of malignant transformation in this molecular subgroup should be addressed in future studies.

Genome sequencing reveals molecular subgroups in oral epithelial dysplasia

Abstract This study aimed to analyze the molecular characteristics of oral epithelial dysplasia (OED), highlighting the pathways and variants of genes that are frequently mutated in oral squamous cell carcinoma (OSCC) and other cancers. Ten archival OED cases were retrieved for retrospective clinicopathological analysis and exome sequencing. Comparative genomic analysis was performed between high-grade dysplasia (HGD) and low-grade dysplasia (LGD), focusing on 57 well-known cancer genes, of which 10 were previously described as the most mutated in OSCC. HGD cases had significantly more variants; however, a similar mutational landscape to OSCC was observed in both groups. CASP8+FAT1/HRAS, TP53, and miscellaneous molecular signatures were also present. FAT1 is the gene that is most affected by pathogenic variants. Hierarchical divisive clustering showed division between the two groups: "HGD-like cluster" with 4HGD and 2LGD and "LGD-like cluster" with 4 LGD. MLL4 pathogenic variants were exclusively in the "LGD-like cluster". TP53 was affected in one case of HGD; however, its pathway was usually altered. We describe new insights into the genetic basis of epithelial malignant transformation by genomic analysis, highlighting those associated with FAT1 and TP53. Some LGDs presented a similar mutational landscape to HGD after cluster analysis. Perhaps molecular alterations have not yet been reflected in histomorphology. The relative risk of malignant transformation in this molecular subgroup should be addressed in future studies.

[Frequency of oral squamous cell carcinoma and oral epithelial dysplasia in oral and oropharyngeal mucosa in Chile]. / Frecuencia de displasia epitelial y carcinoma escamoso en mucosa oral y orofaríngea en Chile, entre los años 1990 y 2009.

BACKGROUND: Oral cancer in Chile corresponds approximately to 1.6% of all cancer cases. There are few studies about oral epithelial dysplasia and oral squamous cell carcinoma in the Chilean population. AIM: To determine the frequency of hyperkeratosis, mild, moderate and severe oral epithelial dysplasia, in situ carcinoma and squamous cell carcinoma of the oral and oropharyngeal mucosa in a registry of the Oral Pathology Reference Institute of the Faculty of Dentistry, Universidad de Chile, in a ten years period. MATERIAL AND METHODS: Review of clinical records and pathological plates of 389 patients, obtained between 1990 and 2009. Cases were selected according to their pathological diagnosis, including hyperkeratosis, oral epithelial dysplasia, in situ carcinoma, squamous cell carcinoma and verrucous carcinoma. RESULTS: Forty four percent of cases were squamous cell carcinoma, followed by hyperkeratosis in 37% and mild epithelial dysplasia in 11%. Squamous cell carcinoma was more common in men aged over 50 years. Most of the potentially malignant disorders presented clinically as leukoplakia and squamous cell carcinoma were clinically recognized as cancer. CONCLUSIONS: In this study, men aged over 50 years are the highest risk group for oral cancer. Early diagnosis is deficient since most of these lesions were diagnosed when squamous cell carcinoma became invasive. Leukoplakia diagnosis is mostly associated with hyperkeratosis and epithelial dysplasia, therefore biopsy of these lesions is mandatory to improve early diagnosis.

Frecuencia de displasia epitelial y carcinoma escamoso en mucosa oral y orofaríngea en Chile, entre los años 1990 y 2009 / Frequency of oral squamous cell carcinoma and oral epithelial dysplasia in oral and oropharyngeal mucosa in Chile

Background: Oral cancer in Chile corresponds approximately to 1.6% of all cancer cases. There are few studies about oral epithelial dysplasia and oral squamous cell carcinoma in the Chilean population. Aim: To determine the frequency of hyperkeratosis, mild, moderate and severe oral epithelial dysplasia, in situ carcinoma and squamous cell carcinoma of the oral and oropharyngeal mucosa in a registry of the Oral Pathology Reference Institute of the Faculty of Dentistry, Universidad de Chile, in a ten years period. Material and Methods: Review of clinical records and pathological plates of 389 patients, obtained between 1990 and 2009. Cases were selected according to their pathological diagnosis, including hyperkeratosis, oral epithelial dysplasia, in situ carcinoma, squamous cell carcinoma and verrucous carcinoma. Results: Forty four percent of cases were squamous cell carcinoma, followed by hyperkeratosis in 37% and mild epithelial dysplasia in 11%. Squamous cell carcinoma was more common in men aged over 50 years. Most of the potentially malignant disorders presented clinically as leukoplakia and squamous cell carcinoma were clinically recognized as cancer. Conclusions: In this study, men aged over 50 years are the highest risk group for oral cancer. Early diagnosis is deficient since most of these lesions were diagnosed when squamous cell carcinoma became invasive. Leukoplakia diagnosis is mostly associated with hyperkeratosis and epithelial dysplasia, therefore biopsy of these lesions is mandatory to improve early diagnosis.

Novel missense mutation of the FAM83H gene causes retention of amelogenin and a mild clinical phenotype of hypocalcified enamel.

OBJECTIVE: Amelogenesis imperfecta (AI) is a group of clinically and genetically heterogeneous inherited conditions, causing alterations in the structure of enamel and chemical composition of enamel matrix during development. The objective of this study was to compare the clinical, radiographic, histological and immunohistochemical phenotypes of subjects affected with hypocalcified AI from three Chilean families and identify causal mutations in the FAM83H gene. DESIGN: The diagnosis was made using clinical, radiographic, histological and genealogical data from the patients, who were evaluated according to the classification criteria by Witkop. PCR and Sanger sequencing of the complete coding sequence and surrounding intron regions of the FAM83H gene were conducted. The structural study of the affected teeth was performed with light microscopy, scanning electron microscopy and immunohistochemistry. RESULTS: The probands of the three families were diagnosed with hypocalcified AI, but in only one of them the missense variant p.Gly557Cys was identified. This variant was not present in the SNP database or in 100 healthy controls and segregated with the disease in the affected family. Using light microscopy, a normal prismatic structure was observed in all three cases. However, the ultrastructure was found to be affected in two of the cases, showing persistence of organic matter including amelogenins. CONCLUSIONS: These results suggest that FAM83H missense mutation reported in one of the families analyzed in this study might cause a phenotype of hypocalcified enamel more attenuated with retention of amelogenin.