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Facts for people and families with a faulty MSH6 gene (Lynch syndrome)

This fact sheet contains general information. Each person should be referred to a genetic service for further information and advice about what a faulty MSH6 gene means for them.

Key Points

  • People with a faulty MSH6 gene have Lynch syndrome (also known as HNPCC).
  • Both men and women with a faulty MSH6 gene have an increased chance of developing bowel (colorectal) cancer.
  • Women with a faulty MSH6 gene have an increased chance of developing uterine (endometrial) and ovarian cancer.
  • Men and women can be referred to a genetic service where experts can provide information, advice and support about their chance of developing cancer and the option of genetic testing.
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MSH6 is a ‘DNA repair’ gene that helps to protect against bowel, uterine and ovarian cancer.

Everyone has two MSH6 genes (one from their mother, and one from their father). If one of the genes is not working, this is known as having a faulty MSH6 gene, or having a MSH6 mutation.

  • Men with a faulty MSH6 gene have about a 20% chance of developing bowel cancer over their lifetime.
  • Women with a faulty MSH6 gene have about a 10% chance of developing bowel cancer over their lifetime.
  • Women with a faulty MSH6 gene have about a 25% chance of developing uterine cancer and a slightly increased chance of developing ovarian cancer over their lifetime.
  • Not everyone who has a faulty MSH6 gene will develop cancer.

Cancer in men and women:

  • To find bowel cancer early, people with a faulty MSH6 gene should have bowel cancer screening every year from age 30 years. This involves having a colonoscopy. Bowel cancer screening might start before the age of 30 years if there is a family history of young onset bowel cancer.  
  • To reduce the chance of getting bowel cancer, doctors may recommend taking daily aspirin.

Cancer in women:

  • There are no reliable methods of screening for uterine or ovarian cancer.
  • To reduce the chance of getting uterine and ovarian cancer, women with a faulty MSH6 gene should have their uterus and ovaries removed (risk reducing hysterectomy with bilateral salpingo-oophorectomy) after they have finished having children, or at around 40 years of age.  

Adult family members of someone with a faulty MSH6 gene can have genetic testing to check who has the faulty gene and who does not. Their doctor can refer them to a genetic service to find out more about their chance of developing cancer and what genetic testing involves.

If a person does have the faulty MSH6 gene: 

  • they can pass it on to their children
  • each child has a 50% (1 in 2) chance of being born with it. Pregnancy planning options are available to people who want to prevent the faulty gene from being passed on.

If a person does not have the faulty MSH6 gene:

  • they have the same chance of developing cancer as the general population (unless there are other factors that increase this risk)
  • they cannot pass it on to their children.
People who decide not to have genetic testing should still get advice about managing their chance of developing cancer.

This cancer genetics fact sheet is a guide only and cannot cover every possible situation. The information provided is not intended to replace discussion with a health professional, and should not be interpreted as medical advice. Use of this document is subject to eviQ's disclaimer available at  www.eviQ.org.au  

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The currency of this information is guaranteed only up until the date of printing, for any updates please check:

https://www.eviq.org.au/p/3453

17 Oct 2018