Functional Variants of the <scp> <i>RAD51</i> </scp> Gene Contribute to Susceptibility to Non‐Syndromic Orofacial Clefts in a Han Chinese Population

OBJECTIVES: Non-syndromic orofacial cleft (NSOFC) is a complex congenital disease caused by genetic and environmental factors, and its aetiology remains unclear. This study aims to investigate the association between potentially functional single-nucleotide polymorphisms (SNPs) in the RAD51 and E2F1 genes and the risk of developing NSOFC in the Han Chinese population. MATERIALS AND METHODS: A total of 200 NSOFC patients and 200 unrelated healthy controls of Han Chinese ancestry were recruited. Five candidate SNPs-rs1801320, rs45507396, rs7180135 and rs11855560 in the RAD51 gene, and rs3213180 in the E2F1 gene-were genotyped using the SNaPshot technique. Statistical and bioinformatics analyses were then performed to evaluate their associations with NSOFC. RESULTS: RAD51 variants were significantly associated with NSOFC. The G allele of rs45507396 was identified as a risk allele, showing significant associations under four genetic models, while rs1801320 was significantly associated with NSOFC under three genetic models. Bioinformatics analyses predicted that hsa-miR-299-5p could bind to rs45507396, which is located within an ESE/ESS binding site and may induce exon skipping, potentially altering RAD51 coding. In contrast, rs1801320 was predicted to be a benign variant with no impact on splicing. Both SNPs are localised within ENCODE-annotated cis-regulatory elements (cCREs), with rs1801320 situated in a promoter-like cCRE and rs45507396 in an enhancer-like cCRE. Additionally, these variants may affect RNA-binding protein interactions, with rs1801320 influencing HNRNPA2B1 binding and rs45507396 affecting SFPQ binding. No significant associations with NSOFC were observed for rs7180135, rs11855560 or rs3213180. CONCLUSION: This study is the first to identify RAD51 variants rs45507396 and rs1801320 as susceptibility loci for NSOFC in the Han Chinese population, providing novel genetic insights and a theoretical basis for further investigation into the molecular mechanisms of NSOFC.