NTHL1-related polyposis

NTHL1-related polyposis (also called NTHL1-associated polyposis or NAP) is a rare inherited condition that increases the risk of developing multiple polyps in the colon and rectum, as well as certain cancers. It is caused by changes (mutations) in both copies of the NTHL1 gene, which normally helps repair damage to DNA. When this gene does not work properly, errors build up in the DNA of cells, especially in the lining of the colon, leading to the growth of adenomatous polyps — small growths that can become cancerous over time if not removed. People with NTHL1-related polyposis typically develop between 10 and 100 colorectal polyps, usually during adulthood. Beyond colorectal cancer, there is also an increased risk of other cancers, including breast cancer, endometrial (uterine) cancer, bladder cancer, skin tumors (particularly basal cell carcinomas), and possibly other tumor types. The condition was only recently described, so our understanding is still growing. Treatment focuses on regular surveillance with colonoscopies to find and remove polyps before they become cancerous. Surgery to remove part or all of the colon may be needed if polyps are too numerous to manage with colonoscopy alone. Screening for other associated cancers is also recommended. Early detection through genetic testing in at-risk families can significantly improve outcomes by allowing surveillance to begin before cancer develops.

Bring these to your next appointment

• Q1.How often should I have a colonoscopy, and when should I start?,What other cancers am I at increased risk for, and what screening do I need?,Should my siblings and other family members be tested for NTHL1 mutations?,Are there any medications or lifestyle changes that could help reduce my polyp or cancer risk?,At what point would you recommend surgery to remove part of my colon?,How will this diagnosis affect my children — what is their risk of being carriers or affected?,Are there any clinical trials or new treatments being studied for this condition?

Common questions about NTHL1-related polyposis