Objective: To investigate the association between DNA polymorphisms, including single-nucleotide polymorphisms (SNPs) and insertion/deletion polymorphisms, in exon 1 and promoter of the CDH1 gene, and the risk of transitional cell carcinoma (TCC) of the urinary bladder (TCCB).
Patients, subjects and methods: This was a hospital-based case-control study of 180 patients with TCCB and 110 normal controls. Genomic DNA was extracted from blood samples of all participants and genotypes determined using polymerase chain reaction and DNA sequencing techniques. Haplotypes were analysed using appropriate software.
Results: SNPs were detected at -160A/C, -73A/C and 178C/T; an inserted oligonucleotide of 5'-CCGTGCCCCAGCC-3' was identified at 234 bp. The -160A allele frequency in the case group was 0.67, statistically higher than in the control group (0.42; P < 0.001), and higher in invasive carcinoma (0.77) than in superficial carcinoma (0.60). For -73C/A and 178C/T SNPs there was no difference among genotypes. The 234 repeat oligonucleotide insertion (2I) frequencies in cases was 0.27, statistically higher than in the control group (0.17; P = 0.01). The most common haplotype in controls was C-A-T-I (28%), the frequency of which was higher than in the TCCB group (6%). The A-A-T-2I was the only variation distribution carrying the -160A allele and was at a statistically higher frequency in the TCCB group (37%, the most common haplotype in cases) than in the control group.
Conclusion: The -160A, 234 2I allele and haplotype A-A-T-2I were risk factors of TCCB. Haplotype C-A-T-I might act as a protective factor for TCCB.