Short answer · Medically reviewed summary · Last updated: 2026-05-08
Lynch Syndrome is a hereditary cancer predisposition syndrome caused by a germline mutation in one of the DNA mismatch repair (MMR) genes. These mutations prevent the body from effectively repairing errors that occur when DNA replicates, significantly increasing the lifetime risk of developing colorectal and various other cancers. What are the genetic causes of Lynch Syndrome? The primary cause of Lynch Syndrome is a pathogenic variant (mutation) in one of the mismatch repair genes: MLH1, MSH2, MSH6, or PMS2.
1 people with Lynch Syndrome have shared their first-person experience on this question at DiseaseMaps.
Which are the causes of Lynch Syndrome?
Causes of Lynch Syndrome explained: genetic and environmental factors, reviewed against medical sources, plus patient perspectives.
Lynch Syndrome is a hereditary cancer predisposition syndrome caused by a germline mutation in one of the DNA mismatch repair (MMR) genes. These mutations prevent the body from effectively repairing errors that occur when DNA replicates, significantly increasing the lifetime risk of developing colorectal and various other cancers.
What are the genetic causes of Lynch Syndrome?
The primary cause of Lynch Syndrome is a pathogenic variant (mutation) in one of the mismatch repair genes: MLH1, MSH2, MSH6, or PMS2. Additionally, mutations in the EPCAM gene can lead to Lynch Syndrome by silencing the MSH2 gene. Think of these genes as the body’s "spell-check" system; when they are faulty, DNA copying errors accumulate, which can eventually lead to the uncontrolled cell growth characteristic of cancer.
Is Lynch Syndrome hereditary?
Yes, Lynch Syndrome follows an autosomal dominant inheritance pattern. This means that if one parent carries the mutation, there is a 50% chance that each child will inherit the genetic predisposition. Because Lynch Syndrome is genetic, it is present from birth in every cell of the body, though it does not guarantee that an individual will develop cancer.
What differentiates causes from risk factors?
The cause of Lynch Syndrome is strictly the genetic mutation inherited from a parent. In contrast, risk factors are secondary influences that may increase the probability or speed at which cancer develops in those already carrying the mutation. These include:
- Lifestyle factors such as smoking, high alcohol consumption, and physical inactivity.
- Dietary patterns, particularly high intake of processed meats and low fiber consumption.
- Age, as the penetrance (likelihood of developing cancer) increases significantly after age 40.
What is the current status of research into Lynch Syndrome?
While the genetic etiology of Lynch Syndrome is well-understood, ongoing research focuses on precision prevention. Scientists are investigating aspirin chemoprevention and immunotherapy treatments that target the high mutation burden found in tumors associated with Lynch Syndrome. Currently, 79 members of the DiseaseMaps community are actively sharing their experiences to help researchers better understand the clinical variability of this condition.
Next steps
- Consult a genetic counselor to discuss family history and potential genetic testing.
- Schedule regular, high-frequency cancer screenings as recommended by a gastroenterologist or oncologist.
- Join the DiseaseMaps.org community to connect with others navigating a Lynch Syndrome diagnosis.
Medical disclaimer: This information is for educational purposes only and should not replace professional medical advice, diagnosis, or treatment.
References
- NIH Genetic and Rare Diseases Information Center (GARD): Lynch Syndrome
- Orphanet: Hereditary non-polyposis colorectal cancer (Lynch Syndrome)
- OMIM (Online Mendelian Inheritance in Man): Mismatch Repair Gene Variants
- Lynch Syndrome International (Patient Advocacy Foundation)
Posted Sep 18, 2017 by Cathy 2500
