ABCB1 variants C3435T and T129C are not associated with colorectal cancer risk

Background: Colorectal cancer (CRC) is one of the most prevalent cancers in Saudi Arabia that is highly characterized with poor survival rate and advanced metastasis. Many studies contribute this poor outcome to the expression of ABC transporters on the surface of cancer cells.
Objectives: In this study, two ABCB1 variants, C3435T and T129C, were examined to evaluate their contribution to CRC risk.
Methods: 125 subjects (62 CRC patients and 63 healthy controls) were involved. The DNA was isolated and analyzed with PCR-RFLP to determine the different genotypes. The hardy-Weinberg equilibrium was performed to determine genotype distribution and allele frequencies. Fisher’s exact test (two-tailed) was used to compare allele frequencies between patients and control subjects.
Results: The study showed that for SNP C3435T, the population of both CRC patients and controls were out of Hardy-Weinberg equilibrium. Genotype distribution for CRC patients was (Goodness of fit χ² = 20, df= 1, P≤0.05), whereas, for the controls the genotype distribution was (Goodness of fit χ² = 21, df =1, P ≤0.05). For SNP T129C, all subjects showed normal (TT) genotype.
Conclusion: There was no significant association between ABCB1 3435C>T and 129T>C polymorphisms with CRC risk.

Keywords
Colorectal cancer; ABCB1 gene; SNP C3435T; SNP T129C; PCR-RFLP; Saudi Arabia.