RAD51 135G>C polymorphism in esophageal cancer and meta-analysis in gastrointestinal tract cancers
Jagmohan Singh Bali1, Vasudha Sambyal1, Kamlesh Guleria1, Sanjana Mehrotra1, Neeti Rajan Singh2, Manjit Singh Uppal2, Mridu Manjari3, Meena Sudan4
1 Department of Human Genetics, Human Cytogenetics Laboratory, Guru Nanak Dev University, Amritsar, Punjab, India
2 Department of Surgery, Sri Guru Ram Das Institute of Medical Sciences and Research, Amritsar, Punjab, India
3 Department of Pathology, Sri Guru Ram Das Institute of Medical Sciences and Research, Amritsar, Punjab, India
4 Department of Radiotherapy, Sri Guru Ram Das Institute of Medical Sciences and Research, Amritsar, Punjab, India
Department of Human Genetics, Human Cytogenetics Laboratory, Guru Nanak Dev University, Amritsar, Punjab
Source of Support: None, Conflict of Interest: None
Background: A functional single-nucleotide polymorphism (SNP), 135G>C in the 5'UTR of the RAD51 gene, affects gene transcription activity with implications for the repair of damaged DNA related to tumorigenesis. Previous limited reported genetic studies to link the 135G>C polymorphism of RAD51 gene to the risk of gastrointestinal tract (GIT) cancers, especially esophageal cancer (EC), have been inconclusive.
Materials and Methods: The polymorphism was evaluated by RFLP-PCR in 252 EC patients and 252 healthy controls from Amritsar, Punjab, India, for case–control study. For a meta-analysis, a total of 78 studies on GIT cancers were assessed, out of which 14 eligible studies (including the present study) comprising 2842 cases and 3224 controls were included. Odds ratios (ORs) with 95% confidence intervals (CIs) and Chi-square test were used to assess the association in different inheritance models.
Results: The GC genotype (OR: 0.45, 95% CI: 0.29–0.68) and C allele (OR: 0.52, 95% CI: 0.36–0.75) were significantly lower (P = 0.0005) in cases as compared to controls. There was no significant association with any genetic model in the meta-analysis.
Conclusion: C allele provides protection for EC in the studied population contrary to previous reports in Polish, Chinese population probably due to ethic differences. Compared with previous meta-analysis on individual GIT cancers, present meta-analysis included all GIT cancers but found no association.