Loss of IGF2 Imprinting: A Potential Marker of Colorectal Cancer Risk

Loss of imprinting (LOI), an epigenetic alteration affecting the insulin-like growth factor II gene ( IGF2 ), is found in normal colonic mucosa of about 30% of colorectal cancer (CRC) patients, but it is found in only 10% of healthy individuals. In a pilot study to investigate the utility of LOI as a marker of CRC risk, we evaluated 172 patients at a colonoscopy clinic. The adjusted odds ratio for LOI in lymphocytes was 5.15 for patients with a positive family history 95% confidence interval (95% CI), 1.70 to 16.96; probability P = 0.002, 3.46 for patients with adenomas (95% CI, 1.14 to 11.37; P = 0.026), and 21.7 for patients with CRC (95% CI, 3.48 to 153.6; P = 0.0005). LOI can be assayed with a DNA-based blood test, and it may be a valuable predictive marker of an individual's risk for CRC.