Single nucleotide polymorphisms of the APC gene and colorectal cancer risk: a case-control study in Taiwan

Background: Colorectal cancer (CRC), which has become especially prevalent in developed countries, is currently the third highest cause of cancer mortality in Taiwan. Mutation of the adenomatous polyposis coli (APC) gene, a tumour suppressor, is thought to be an early event in colorectal tumourigenesis. To date, however, no large-scale screening for APC gene variants in Chinese subjects has been performed. The present study was undertaken to identify APC gene variants that are significantly associated with the occurrence of CRC in Taiwanese subjects. Methods: In order to compare the genotype distribution of variant sites, the full-length APC genes of 74 healthy individuals and 80 CRC patients were sequenced. Results: Among the 154 Taiwanese subjects examined in this study, three new mutations, but no previously reported mutations, were found. One deletion at codon 460 leading to a frameshift and two missense mutations resulting in p. V1125A and p. S1126R substitutions were identified. Additionally, three high risk genotypes associated with three single nucleotide polymorphisms and one low risk genotype at codon 1822 were identified. Conclusion: The findings of this case-control study are consistent with the proposal that Taiwanese subjects differ from other subjects with respect to phenotypic presentation of APC and CRC risk.