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Understanding Your Positive MLH1 Genetic Test Result

Information for patients with a pathogenic mutation or variant, likely pathogenic

5 Things To Know

1 MLH1 mutation Your testing shows that you have a pathogenic mutation or a variant that is likely pathogenic in the MLH1 gene.
2 Lynch syndrome People with MLH1 mutations have Lynch syndrome, previously known as hereditary non-polyposis colorectal cancer (HNPCC).
3 Cancer risks You have an increased chance to develop colorectal, endometrial/uterine, stomach, ovarian, small bowel, and other types of cancer.
4 What you can do There are risk management options to detect cancer early or lower the risk to develop cancer. It is important to discuss these options with your doctor, and decide on a plan that best manages your cancer risks.
5 Family Family members may also be at risk – they can be tested for the MLH1 mutation that was identified in you.

MLH1 Mutations in the Family

There is a 50/50 random chance to pass on a MLH1 mutation to your sons and daughters. The image to the right shows that both men and women can carry and pass on these mutations.

Asset 1 Has MLH1 mutation No MLH1 mutation

Understanding Your Positive MLH1 Genetic Test Result

Information for patients with a pathogenic mutation or variant, likely pathogenic

Result mutation Your testing shows that you have a pathogenic mutation (a disease-causing change in the gene, like a spelling mistake) or a variant that is likely pathogenic in the MLH1 gene. Both of these results should be considered positive.
Gene MLH1 Everyone has two copies of the MLH1 gene, which we randomly inherit from each of our parents. Mutations in one copy of the MLH1 gene can increase the chance for you to develop certain types of cancer in your lifetime.
Condition Lynch Syndrome People with MLH1 mutations have Lynch syndrome, which was previously known as hereditary non-polyposis colorectal cancer (HNPCC).
Cancer Risks Increased You have an increased chance to develop colorectal, endometrial/uterine, stomach, ovarian, small bowel, brain, skin, hepatobiliary tract, upper urinary tract, brain, sebaceous, prostate, and possibly other types of cancer.
Screening Options for women Options for early detection and prevention for uterine and/or ovarian cancer may include: random endometrial biopsies, transvaginal ultrasounds, CA-125 blood test, and options for preventive surgeries. Talk to your doctor about which options may be right for you.
Screening Options for men & women Options for early detection and prevention for men and women include: colonoscopy, upper endoscopy, and urinalysis (a test of your urine). Talk to your doctor about which options may be right for you.
Risk Management varies Risk management decisions are very personal, and the best option depends on many factors. Screening typically begins earlier than the general population and is often more frequently performed. It is important to discuss these options with your doctor.
Family Members 50/50 chance Your close relatives (like your parents, brothers, sisters, children) have a 50/50 random chance of inheriting the MLH1 mutation that you carry, and other family members (like your aunts, uncles, cousins) may also inherit it. Your relatives can be tested for this same mutation. Depending on the family history, those who DO NOT have it may not have an increased chance (above the general population) to develop cancer.
Next Steps discuss It is recommended that you share this information with family members so they can learn more and discuss this with their healthcare providers.
Reach Out resources

Please discuss this information with your healthcare provider. The cancer genetics field is continuously evolving, so updates related to your MLH1 result, medical recommendations, and/or potential treatments may be available over time. This information is not meant to replace a discussion with a healthcare provider, and should not be considered or interpreted as medical advice.

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