What are symptoms of Lynch syndrome? How to diagnose Lynch syndrome? Lynch syndrome life expectancy can be good. But you need regular colon cancer screening. Let's start with Lynch syndrome. Most colorectal cancer cases are not inherited. But there is a particular familial colorectal cancer syndrome called Lynch syndrome. Lynch syndrome causes colon cancer in much younger patients. Dr. Anton Titov, MD. Lynch syndrome also increases frequency of some other cancers. You are a major expert in Lynch syndrome. What is Lynch syndrome? How do people usually find out that they have Lynch syndrome? What are the consequences of Lynch syndrome diagnosis for screening and treatment of colorectal cancer? Dr. C. Richard Boland, MD. I think that we need to have a historical perspective on how we figured out what the hereditary colon cancer syndromes were. In the past doctors thought that the only familial form of colorectal cancer was familial adenomatous polyposis - it has a very distinct phenotype. Patients have hundreds or even thousands of polyps in the colon. And that was thought to be it. The first case of familial colon cancer was reported in 1913 by a University of Michigan pathologist. In the 1960s and 1970s it was clear that there were some familial colorectal cancer families that did not have polyposis. They had something else. Dr. Henry Lynch understood the significance of that story. I also started to research familial colon cancer. But from the late 1960s and early 1970s and until 1993 there were disputes whether such inherited colon cancer disease existed. Because we have no biomarker to know that we were dealing with inherited colon cancer syndrome. In 1993 the molecular signature, the genetic signature called microsatellite instability was discovered. It was immediately linked to hereditary colon cancer. And suddenly we were able to identify a group of the families with hereditary colon cancer. And within 9 months hereditary colon cancer was linked to several DNA mismatch repair genes. So, at this time, Lynch syndrome is the hereditary colorectal cancer syndrome caused by a germline mutation in a DNA mismatch repair gene. There are 4 genes that cause Lynch syndrome: MSH2, MLH1, MSH6 and PMS2. Any of these genes can cause Lynch syndrome. Although the clinical manifestations of Lynch syndrome are slightly different, depending on which gene mutation causes Lynch syndrome in a patient.