Errors in genetic testing are unfortunately commonplace. One of the most common genetic testing errors involves recognizing that genetic testing is appropriate but ordering the wrong test. For instance, people who have a personal and/or family history suggestive of Lynch syndrome may mistakenly only have the BRCA1 and BRCA2 genes tested.
In one such case, two sisters diagnosed with early-onset ovarian cancer tested BRCA negative. Doctors told them, “Lightning struck twice.” It wasn’t lightning though. It was Lynch syndrome. A detailed family history revealed the sisters had multiple family members with cancers of the uterus, gastrointestinal tract, and urinary tract. The takeaway here is the importance of genetic counseling. Ideally, a certified genetic counselor should assess your case before you have genetic testing to ensure the correct tests are ordered and after your testing, so that your results are interpreted and applied accurately.
Lynch syndrome is a hereditary cancer syndrome that can be caused by mutations in one of five different genes. These include MLH1, MSH2, MSH6, PMS2, and EPCAM. People with Lynch syndrome are at increased risk to develop colorectal, uterine, and ovarian cancers, as well as cancers of the gastrointestinal and urinary tracts. They are more likely to receive a cancer diagnosis at a younger age, often before age 50. Their risk to develop more than one of these cancers is higher. Skin findings, such as sebaceous adenomas and carcinomas, can also occur.
Lynch syndrome affects both men and women. If someone has this condition, there is a 50% chance to pass it to each child. Luckily, genetic counseling and testing are available. When we know that a person has Lynch syndrome, providers can offer early and more aggressive surveillance, surgeries, and medications that can detect cancer sooner and/or reduce the risk of ever developing cancer.
If any of the following signs are in your personal and/or family history, you may wish to explore your options for genetic counseling and testing for the genes involved in Lynch syndrome:
- Early-onset colon or uterine cancer before age 50
- Clusters of colon, uterine, ovarian, biliary, or urinary tract cancers on the same side of the family
- One family member who has developed multiple primary (new) colon, uterine, ovarian, or urinary tract cancers
- Sebaceous carcinomas/adenomas, especially in the context of a personal or family history of any of the above cancers
- Any Lynch syndrome-related tumor (e.g., colorectal or uterine) with abnormal MSI (microsatellite instability) or IHC (immunohistochemical) testing
This article was originally published on March 6, 2019.