Genetic Testing
Genetic testing for Lynch’s syndrome can be divided into four categories: tumor tissue testing, comprehensive gene testing, single-site testing1, and next-generation sequencing. These different types of genetic testing may be suggested according to the identified presence of a genetic mutation in the family or after colon tumor tissue has been collected.
- Tumor testing is conducted after collecting colon tumor tissue to detect the presence of a genetic mutation. A negative result will most likely mean the cancer is sporadic, while a positive result will require further testing to isolate the causative mutation.
- Single-site testing is suggested for patients to test for the specific genetic mutation in the family. This applies when a relative has already had genetic testing and a mutation causing Lynch syndrome has been identified.
- Comprehensive testing is usually performed when tumor tissue is not available and a family genetic mutation has not been identified. Comprehensive testing spans MLH1, MSH2, MSH6, PMS2, and EPCAM genes. Since these genes are linked to Lynch Syndrome, testing should be performed on a family member who suffers from or has had a Lynch Syndrome related cancer.
- Next-generation DNA sequencing (NGS) testing provides a possible method of detection for a broader panel of cancer hereditary genes. In the past, single-site testing for Lynch syndrome has shown to be more cost-effective for the patient. However, now with next-generation sequencing, comprehensive testing as well as testing for genes beyond the five linked to Lynch syndrome may be of negligible increased cost. Emerging data from NGS testing results have identified individuals suffering from colorectal cancer who have a genetic mutation not part of the Lynch syndrome genes2. Obtaining additional genetic background information at a similar cost may be of significant value to the patient, family, and healthcare provider.
|
|