Interaction between retinol intake and ISX rs5755368 polymorphism in colorectal cancer risk: a case-control study in a Korean population

We conducted a hospital-based case-control study to examine whether the ISX rs5755368 gentic polymorphism is associated with the effect of dietary retinol consumption on colorectal cancer risk. To identify the association between dietary retinol and CRC risk, we recruited 923 CRC patients and 1846 controls. Dietary retinol intake was assessed using a semiquantitative food frequency questionnaire. For genetic analysis, genotype data were available for 1419 patients (600 cases and 819 controls) out of the total study population. Genomic DNA was extracted from participants? blood samples following the manufacturer?s instructions using the MagAttract DNA Blood M48 Kit (Qiagen, Hilden, Germany) and BioRobot M48 automatic extraction equipment (Qiagen). SNP genotyping was performed using an Illumina MEGA-Expanded Array (Illumina Inc., CA, USA) including 123K SNPs.