Structural Perturbations and Destabilizing Mutations in RAD51C and RAD51D Reveal Mechanisms of Cancer Risk

Breast and ovarian cancers remain among the most prevalent malignancies affecting women worldwide, with only 20% of hereditary cases explained by BRCA1/2 mutations. This highlights the importance of alternative susceptibility genes such as RAD51C and RAD51D, which play essential roles in homologous recombination repair (HRR). In this study, a comprehensive in silico analysis was conducted to identify deleterious non-synonymous single nucleotide polymorphisms (nsSNPs) in RAD51C and RAD51D that may contribute to genomic instability and increased cancer risk. A total of 19,195 SNPs were retrieved and analyzed using multiple computational tools including SIFT, PolyPhen-2, PANTHER, PROVEAN, PhD-SNP, SNP&GO, I-Mutant, and MUpro. Eleven high-risk nsSNPs in RAD51C and several in RAD51D were identified, primarily affecting the ATP-binding and DNA repair domains. Structural modeling, docking, and molecular dynamics simulations revealed that mutations such as R212H, L219S, and L262V in RAD51C and S207L, S207P, and A210E in RAD51D significantly alter protein stability, flexibility, and binding affinity with interaction partners like XRCC2, RAD51B, and RAD51C. These alterations may compromise DNA repair mechanisms, contributing to carcinogenesis. Our findings underscore the utility of integrated computational approaches in identifying pathogenic variants and provide a molecular basis for understanding RAD51C/D-related cancer susceptibility. This work lays the groundwork for future experimental validation and supports the application of personalized medicine in HR-deficient tumors.