The Relationship Between Killer Cell Immunoglobulin-Like Receptors and HLA-C Polymorphisms in Colorectal Cancer in a Saudi Population

Aims: We performed an association study to evaluate the contribution of 16 killer cell immunoglobulin-like receptor (KIR) genotype polymorphisms and the HLA-C1 and -C2 ligands in the development of colorectal cancer (CRC) in Saudi Arabian patients. Methods: A total of 52 patients with different stages of malignant CRC as well as 70 healthy Saudi controls were enrolled at the King Khalid University Hospital. Results: Our results showed that the frequency of the activating mutations KIR2DS1, 2DS2, 2DS3, 2DS5, and 3DS1 was significantly higher in CRC patients compared to controls. The 3DS1 gene contributed to the highest risk of CRC (odds ratio [OR]=16.25, p<0.0001), followed by 2DS1 (OR=8.6; p<0.0001). The distributions of HLA-C1 and -C2 ligands were not significantly different between patients and controls. Analyses of different combinations of KIR genes with their HLA-C1 and -C2 ligands show that the frequency of 2DL3 in the presence of its ligand, the allotype C1, was significantly more prevalent in patients compared to controls. In addition, 2DL2 and 2DL3 that were aggregated in combination with the ligand, HLA-C1, were found to be more highly associated mainly with the homozygote HLA-C1/C1 (p=0.03; OR=2.6). The activating mutations 2DS1 and 2DS2 when combined with their respective ligands, HLA-C2 and -C1, showed highly significant associations with CRC development. Conclusion: This study supports a key role for KIR gene mutations in the development of CRC, especially in association with their ligands.