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What is Lynch Syndrome?
Updated on June 26, 2023
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What is Lynch Syndrome?
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Lynch syndrome, also known as hereditary nonpolyposis colorectal cancer (HNPCC), is a condition passed down from parents to children.1

Lynch syndrome is associated with a genetic predisposition to different types of cancer. It increases your risk of developing colorectal or endometrial cancer. 

It also increases your risk for various other types of cancer. Statistics suggest that Lynch syndrome contributes to 2 to 4 percent of all colorectal cancer cases and approximately 2.5 percent of endometrial cancer cases.

This article aims to provide reliable information about Lynch syndrome and help those affected, their families, and anyone interested in learning more about it.

What Causes Lynch Syndrome?

Lynch syndrome is one of the most common familial cancer syndromes caused by a genetic mutation. An estimate suggests 1 in 300 people may carry the altered gene related to it.1 

Lynch syndrome is caused by a germline mutation in any of the five mismatch repair (MMR) genes. A germline mutation occurs in the reproductive cells.

Errors during the cell process division can cause gene mutations.

Your mother or father can either pass down the gene mutation, and it’ll be present in all the cells in your body. 

Families with Lynch syndrome have a higher risk of developing many types of cancer, including colon cancer.

MMR genes are responsible for correcting DNA errors that occur during the replication process.3

The five MMR genes are:

  • MLHL
  • MSH2
  • MSH6
  • PMS2

However, not all families with Lynch syndrome have identifiable alterations with these MMR genes. Researchers are still identifying other genes linked with this genetic condition.

Lynch syndrome follows an autosomal dominant inheritance pattern. It means you can inherit the condition even if only one of your parents carries the mutated gene.1 

autosomal dominant inheritance pattern

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Lynch Syndrome Risk Factors

People with Lynch syndrome face an increased risk of developing multiple types of cancers during their lifetime.

The lifetime risk of colorectal cancer can be up to 80 percent. On the other hand, the risk of endometrial cancer can reach up to 60 percent.

The most common cancers linked with Lynch Syndrome include:

  • Colorectal
  • Endometrial or uterine
  • Ovarian 
  • Stomach
  • Liver
  • Kidney
  • Brain
  • Certain types of skin cancer

How is Lynch Syndrome Diagnosed?

An early diagnosis of Lynch syndrome is critical for detecting and treating colon and rectal cancers.

Doctors rely on two sets of guidelines to determine if testing is appropriate for you.

Diagnostic Criteria and Screening

The diagnostic criteria for Lynch Syndrome serve as a roadmap for identifying who may be at a higher risk for this hereditary condition.

1. Amsterdam criteria

The Amsterdam criteria are based on family history. Doctors found that families with Lynch syndrome typically have specific characteristics. 

They use these criteria if three relatives in two or more generations have colorectal cancer, of which:

  • One of the affected family members was a first-degree relative (parent, brother or sister, or child) of the other two
  • At least one family member was diagnosed when they were below 50 

If all of these conditions apply to your family, then consider seeking genetic counseling. Although meeting all the Amsterdam criteria doesn’t necessarily mean you have Lynch syndrome, it’s good to be sure about your risks.

2. Revised Bethesda guidelines

The second set of criteria is known as the revised Bethesda guidelines. 

It helps determine if a person with colorectal cancer should undergo testing for genetic changes linked with Lynch Syndrome.

The guideline includes that the person experience at least one of the following:4

  • Diagnosed with colorectal cancer before the age of 50
  • Had a second colorectal cancer or another Lynch Syndrome-related cancer
  • Diagnosed with cancer before the age of 60, and cancer exhibits specific qualities associated with Lynch Syndrome under microscopic check
  • Has a first-degree relative who was diagnosed with colorectal cancer or another Lynch Syndrome-related cancer before the age of 50
  • Has two or more first- or second-degree relatives diagnosed with colorectal cancer or another Lynch Syndrome-related cancer at any age

If a person with colorectal cancer meets the Bethesda criteria, doctors will advise microsatellite instability (MSI) testing.

Microsatellites are DNA regions with repeated sequences that show instability when mismatch repair malfunctions.

Should MSI be detected, they typically recommend further testing for Lynch Syndrome-associated gene mutations.


The screening procedures for Lynch syndrome include the following:

1. Genetic Testing

If you have a family history of Lynch syndrome, your doctor can recommend a genetic test. Testing helps assess your risk of developing cancer linked to the condition.

A genetic test is often done using a blood sample. Once your doctor confirms you have a genetic mutation linked to Lynch syndrome, they’ll schedule you for regular screening.

2. Colonoscopy

A colonoscopy is the top choice for diagnosing Lynch Syndrome. It's the most effective method for detecting polyps or cancer since it enables doctors to examine the entire bowel.5

Preparations might involve a liquid diet, an enema, and laxatives to clear your colon of stool. It ensures optimal visibility of your bowels.

During a colonoscopy, your doctor inserts the colonoscope through the rectum and into the anus and large intestine. The colonoscope helps them inspect for cancer or polyps.

If needed, biopsy forceps can be passed through the scope. It can collect a small tumor tissue sample for further testing. If a polyp is detected, it can be removed using the colonoscope.

You’ll usually be sedated before undergoing the procedure. But you may experience some cramping or discomfort during the process.

3. Endometrial biopsy

Women at risk for Lynch syndrome need an endometrial biopsy. It is vital if they're experiencing abnormal bleeding symptoms.

The procedure involves your doctor removing a small tissue sample from your endometrium (the lining of your uterus).

They’ll send the sample to a lab to examine the cells for cancer or other abnormalities. Your healthcare provider may perform an annual endometrial biopsy from age 30 to 35.

4. Microsatellite Instability (MSI) Testing and Immunohistochemistry (IHC) Testing

MSI and IHC tests are screening tools. They assess how likely your cancer resulted from a Lynch syndrome gene mutation.

A positive test result suggests the cancer might be linked to a gene mutation. You can proceed with genetic blood testing to confirm.5

Management and Prevention

Reducing your risk of developing cancer with Lynch syndrome involves regular screening, preventive surgeries, and lifestyle changes.

Regular screening

Regular checkups and screenings are essential for early detection intervention. They can significantly impact the prevention and management of your condition.

  • Colorectal cancer colonoscopies are recommended every 1 to 2 years. They can begin at a younger age than the general population.6
  • Women with Lynch Syndrome should also have the following tests to screen for endometrial and ovarian cancers:
    • Regular pelvic exams
    • Transvaginal ultrasounds
    • Endometrial biopsies
  • Doctors may recommend additional screenings for other Lynch Syndrome-associated cancers, such as:
    • Gastric
    • Urinary tract
    • Pancreatic cancer

Preventive surgeries

In some cases, doctors may recommend preventive surgery to reduce the risk of certain cancers.

For example, doctors may suggest removing the uterus, fallopian tubes, and ovaries for women at high risk of endometrial and ovarian cancer.

Similarly, they may advise considering a colectomy for someone at risk of colorectal cancer. It is a procedure for the removal of part or all of the colon.

Lifestyle changes

Adopting a healthy lifestyle can help lower your overall cancer risk. You can start taking care of your health today by:

  • Maintaining a balanced diet rich in fruits, vegetables, and whole grains
  • Engaging in regular physical activity
  • Maintaining a healthy weight
  • Limiting your alcohol consumption
  • Avoiding smoking

Living with Lynch Syndrome

Living with Lynch syndrome requires an attentive and proactive approach to maintaining your health. Here are some essential tips to help you manage your condition effectively:

  • Consult a certified genetic counselor to understand your genetic mutation. It can help you determine the appropriate screening measures.
  • Discuss therapy with your doctor. Choose a gastroenterologist experienced in Lynch Syndrome for your colonoscopies.
  • Regular screenings are essential for early detection and prevention.
  • Schedule your screenings around the same time each year to make them easier to remember. Opt for healthcare providers that accommodate back-to-back appointments for convenience.
  • Pay close attention to your body and consult your healthcare provider if you notice any abnormal changes.

Coping Strategies

These coping strategies can help people with Lynch syndrome to minimize the impact of their condition on their lives.

Balanced diet

Consuming a well-rounded diet is essential for overall health, especially if you’re living with Lynch syndrome.

Here are some tips on what to eat and avoid to help reduce your risk of developing cancer:

  • Consume more leafy greens
  • Limit red meat intake
  • Avoid processed foods

However, it’s important to consult a certified genetic counselor. They can work with you on a personalized approach based on your genetic makeup and lifestyle.

Physical activity

Several studies have linked physical activity to numerous health benefits. The benefits include a reduced risk of certain cancers.

Aim for at least 150 minutes of moderate or 75 minutes of vigorous exercise in a week.8

Managing stress

Effective stress management is essential for people with Lynch Syndrome. Chronic stress can weaken the immune system and increase the risk of illnesses, including cancer.

Develop healthy coping strategies, such as:

  • Meditation
  • Yoga
  • Deep breathing exercises
  • Engaging in hobbies that bring relaxation and joy

Support and Resources

Several groups offer support to people with Lynch Syndrome and their families. They can provide access to support groups, educational conferences, and valuable health information.

  1. Dana-Farber Cancer Institute: The Lynch Syndrome Center at Dana-Farber offers specialized care for people with Lynch Syndrome. It provides resources, expertise, and the latest treatment options. Visit their website at
  1. FORCE (Facing our Risk of Cancer Empowered): FORCE is a nonprofit organization. It supports people and families affected by hereditary cancers, including Lynch Syndrome. They offer educative resources, peer support, and advocacy initiatives. Find more information at
  1. AliveAndKickn: AliveAndKickn is dedicated to improving the lives of people affected by Lynch Syndrome through research, education, and screening. Visit their website at
  1. Lynch Syndrome International: This organization provides support, information, and assistance to people with Lynch Syndrome and their families. They offer a variety of resources, including support groups and educational materials. Visit their website at
  1. National Comprehensive Cancer Network (NCCN): The NCCN offers guidelines and resources for managing and treating Lynch Syndrome. Visit their website at
  1. The Colon Cancer Foundation: This foundation provides resources, education, and support for those affected by colorectal cancer and associated syndromes, including Lynch Syndrome. Visit their website at

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Updated on June 26, 2023
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Updated on June 26, 2023
Cristine Santander
Cristine Santander
Content Contributor
Cristine Santander is a content writer for KnowYourDNA. She has a B.S. in Psychology and enjoys writing about health and wellness.
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