Whole-Exome Sequencing Identifies Recurrent Germline-Associated and Somatic Variants in Oral Squamous Cell Carcinoma from Southwest India

Background: Oral squamous cell carcinoma (OSCC) remains a major public health challenge, particularly in South Asian populations where environmental exposures such as tobacco and areca nut consumption contribute significantly to disease burden. Although genomic studies have improved understanding of oral cancer biology, population-specific genomic data from high-risk Indian populations remain limited. This study aimed to characterize the genomic landscape of OSCC using whole-exome sequencing (WES) of fresh biopsy specimens obtained from patients residing along the southwest coast of Karnataka, India. Methods: Paired tumor and adjacent normal tissues from ten OSCC samples (total n = 20 samples) were subjected to WES to identify somatic and germline-associated variants. Matched tumor–normal comparative analysis, variant annotation, and population frequency assessment using established genomic databases, including gnomAD, were performed to characterize the mutational profile. The findings were further compared with a previously analyzed regional cohort comprising 66 OSCC patients to evaluate recurrence patterns and population relevance. Results: The analysis identified a broad background of recurrent germline-associated variants alongside a comparatively limited number of tumor-specific somatic mutations, consistent with the expected predominance of constitutional genetic variation relative to acquired coding alterations in tumor samples. Recurrent variants were observed in genes associated with DNA repair, immune signaling, inflammatory responses, and pharmacogenomic pathways, including XRCC1, ITPKB, ABCB1, and OPRM1, whereas somatic alterations were primarily detected in established cancer-associated genes such as TP53, CDKN2A, and TERT. Conclusions: Several recurrent variants demonstrated high frequencies in South Asian populations, suggesting that they may represent recurrent population-associated variants of potential biological or pharmacogenomic relevance that require validation in larger cohorts. KEGG pathway enrichment analysis identified pathways related to cancer, chemical carcinogenesis, metabolic regulation, and xenobiotic response. Overall, these findings provide preliminary insights into the population-specific genomic characteristics of OSCC in this regional cohort and highlight the need for larger validation studies to determine the biological significance and reproducibility of these findings.