Isom CA, et al. - Using the Tennessee Colorectal Polyps Study, researchers performed a case-control study to determine the causal relationship between elevated arachidonic acid (ARA) concentrations in erythrocyte membranes and risk of developing colorectal polyps. They conducted Mendelian randomization (MR) analysis using rs174537 as an instrumental variable (IV). No statistically significant difference was found in: age, sex, alcohol use, body mass index (BMI), or NSAID use when stratified by the rs174537 alleles. A strong association was found between genotype and erythrocyte membrane ARA concentrations. No statistically significant association was found between elevated erythrocyte membrane ARA concentrations and colorectal polyps in this MR study.