Lynch syndrome is now considered to comprise four different heritable conditions, each caused by changes in a different gene and resulting in different levels of cancer risk. We previously calculated and published these risks according to age and sex, using the Prospective Lynch Syndrome Database. We also showed that colonoscopy does not prevent bowel cancer in three of the four Lynch syndromes. The new study by Fummey and colleagues (jmg-2024-110385) confirmed this.  Bowel cancers diagnosed in people with Lynch syndrome who have regular colonoscopy is, however, usually curable and colonoscopy surveillance is therefore recommended to improve survival. In addition, Fummey and colleagues reported that the fourth of the Lynch syndromes, caused by the PMS2 gene, is more frequent but has lower cancer risk than reported previously. (By Dr. Pål Møller, on behalf of the authors, https://jmg.bmj.com/content/early/2024/10/07/jmg-2024-110385 )