A Novel Tri-Allelic Insertion/Deletion Polymorphism in the Promoter of p21Waf1/Cip1 and the Association with Gastric Cancer

Aims: p21Waf1/Cip1 is a cyclin-dependent kinase inhibitor that is pivotal in arresting cellular growth in terminal cell differentiation and apoptosis. Thus, the existence of natural variants of p21Waf1/Cip1 could be linked to specific cancer. The purpose of this report was to identify a novel tri-allelic insertion/deletion (INDEL) polymorphism (rs4135235) involving a poly-T sequence in the promoter region of p21Waf1/Cip1 gene and to explore its role in gastric cancer (GC). Method: A total of unrelated 676 subjects (376 GC patients; 300 cancer-free controls) were enrolled in the study, and genomic DNA was obtained from each subject for genotyping. PCR-directed sequencing technique was used to detect the genotypes of the polymorphism. TA cloning was used to confirm the existence of three alleles. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated by unconditional logistic regression analysis. Results: Six genotypes (9T/9T, 10T/10T, 11T/11T, 9T/10T, 10T/11T, and 9T/11T) and three alleles (9T...