A 60-year-old man was diagnosed with adenocarcinoma of the end of the ileum. No suspicious findings of submucosal infiltration were observed macroscopically, so EMR was performed for batch resection. Meanwhile, his daughter was examined at another hospital and found to possess a genetic mutation that indicated a family history of colorectal cancer. When he also underwent a genetic test, he was found to possess the same genetic mutation as her. Hereditary gastrointestinal cancer such as Lynch syndrome was considered, but no specific gene mutation could be detected. Gastrointestinal and genetic screening tests are important, and more cases should be studied in the future.
