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Reviewed May 2013
What is Lynch syndrome?
Lynch syndrome, often called hereditary nonpolyposis colorectal cancer (HNPCC), is an inherited disorder that increases the risk of many types of cancer, particularly cancers of the colon (large intestine) and rectum, which are collectively referred to as colorectal cancer. People with Lynch syndrome also have an increased risk of cancers of the stomach, small intestine, liver, gallbladder ducts, upper urinary tract, brain, and skin. Additionally, women with this disorder have a high risk of cancer of the ovaries and lining of the uterus (the endometrium). People with Lynch syndrome may occasionally have noncancerous (benign) growths (polyps) in the colon, called colon polyps. In individuals with this disorder, colon polyps occur earlier but not in greater numbers than they do in the general population.
How common is Lynch syndrome?
In the United States, about 140,000 new cases of colorectal cancer are diagnosed each year. Approximately 3 to 5 percent of these cancers are caused by Lynch syndrome.
What genes are related to Lynch syndrome?
Variations in the MLH1, MSH2, MSH6, PMS2, or EPCAM gene increase the risk of developing Lynch syndrome.
The MLH1, MSH2, MSH6, and PMS2 genes are involved in the repair of mistakes that occur when DNA is copied in preparation for cell division (a process called DNA replication). Mutations in any of these genes prevent the proper repair of DNA replication mistakes. As the abnormal cells continue to divide, the accumulated mistakes can lead to uncontrolled cell growth and possibly cancer.
Mutations in the EPCAM gene also lead to impaired DNA repair, although the gene is not itself involved in this process. The EPCAM gene lies next to the MSH2 gene on chromosome 2; certain EPCAM gene mutations cause the MSH2 gene to be turned off (inactivated), interrupting DNA repair and leading to accumulated DNA mistakes.
Although mutations in these genes predispose individuals to cancer, not all people who carry these mutations develop cancerous tumors.
How do people inherit Lynch syndrome?
Lynch syndrome cancer risk is inherited in an autosomal dominant pattern, which means one inherited copy of the altered gene in each cell is sufficient to increase cancer risk. It is important to note that people inherit an increased risk of cancer, not the disease itself. Not all people who inherit mutations in these genes will develop cancer.
Where can I find information about diagnosis or management of Lynch syndrome?
These resources address the diagnosis or management of Lynch syndrome and may include treatment providers.
General information about the diagnosis and management of genetic conditions is available in the Handbook. Read more about genetic testing, particularly the difference between clinical tests and research tests.
To locate a healthcare provider, see How can I find a genetics professional in my area? in the Handbook.
Where can I find additional information about Lynch syndrome?
You may find the following resources about Lynch syndrome helpful. These materials are written for the general public.
You may also be interested in these resources, which are designed for healthcare professionals and researchers.
What other names do people use for Lynch syndrome?
What if I still have specific questions about Lynch syndrome?
Where can I find general information about genetic conditions?
The Handbook provides basic information about genetics in clear language.
These links provide additional genetics resources that may be useful.
What glossary definitions help with understanding Lynch syndrome?
autosomal ; autosomal dominant ; benign ; cancer ; cell ; cell division ; chromosome ; colon ; colorectal ; DNA ; DNA repair ; DNA replication ; endometrium ; familial ; gallbladder ; gene ; intestine ; neoplasms ; population ; rectum ; stomach ; syndrome
You may find definitions for these and many other terms in the Genetics Home Reference Glossary.
See also Understanding Medical Terminology.
References (16 links)
The resources on this site should not be used as a substitute for professional medical care or advice. Users seeking information about a personal genetic disease, syndrome, or condition should consult with a qualified healthcare professional. See How can I find a genetics professional in my area? in the Handbook.