MSFinals-6368
A 28-year-old male patient visits their GP complaining of abdominal pain and bloody diarrhoea that began six weeks ago. He has never experienced anything like this before and believes he may have lost some weight in the past three months. When asked about his family history, he mentions that his father was diagnosed with bowel cancer at the age of 30, and he remembers his grandfather having a stoma before he passed away when the patient was a child. The GP suspects bowel cancer and is concerned about a potential genetic abnormality. During colonoscopy, a large tumour is discovered in the ascending colon near the hepatic flexure, but the rest of the colonic mucosa appears normal. What is the most probable underlying genetic issue?