Lynch syndrome

Hereditary non-polyposis colorectal cancer (HNPCC)


Type of disease: Rare conditions

Lynch syndrome is a genetic condition that causes an increased risk for several different types of cancer. People with Lynch syndrome have a lifetime cancer risk of 52-82% for colorectal (cancer of the colon or rectum), 25-60% for endometrial (cancer of the inner lining of the uterus), 6-13% for gastric (stomach cancer) and 4-12% for ovarian cancer. Lynch syndrome also causes a higher risk for cancer of the upper urinary tract, kidneys, small intestine, skin, and brain.

Lynch syndrome is caused by a mutation (change) in one of several genes important in our cell’s DNA (genetic code) repair. Mistakes happen when a cell makes a copy of its DNA during mitosis. Mitosis is the way our body’s cells make more cells (one cell splits into 2 cells). The MLH1, MSH2, MSH6, PMS2, and EPCAM genes make proteins which find and fix mistakes in the newly copied DNA. If one of these DNA repair proteins is missing, there is a greater chance for DNA copy errors to not be fixed, leading to the increased risk of certain cancers.

Mutations that cause Lynch syndrome can occur by chance for the first time in a family (de novo), but are often inherited from a parent in an autosomal dominant manner (a mutation in one copy of the gene causes the condition). People with Lynch syndrome will have a 50% chance of passing it on to any of their children.

Lynch syndrome is often diagnosed based on an individual’s cancer and family history. Genetic testing is used to confirm the diagnosis. If you or someone in your family has been diagnosed with Lynch syndrome, talk with a genetic counselor to discuss inheritance risks and testing options. Most doctors and specialists recommend you receive routine cancer screenings to catch any developing cancer in the early stages. Talk with your doctor about the most current options to screen for cancer. Support groups are a good source of information and help connect you with others living with Lynch syndrome.

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