About Lynch Syndrome
How is Lynch syndrome diagnosed?
Family History
Screening for Lynch syndrome includes a medical and family history review and construction of a
multi-generation family tree. A genetic counselor usually conducts this screening process and
assesses the family’s risk. Further tests will be considered if the medical and family history
review suggests the possibility of Lynch syndrome.
Testing
Special tests can be performed on a colon tumor or other tumor. These screening tests are called
microsatellite instability (MSI) assay and immunohistochemical (IHC) analysis. The tests look
for characteristics in tumors that may be caused by Lynch syndrome. They can identify which
gene may be responsible for Lynch syndrome in the family. Genetic testing is recommended if
the pathology results suggest the possibility of Lynch syndrome.
Genetic testing looks for mutations in the Lynch syndrome genes. Testing is usually performed
on a blood sample. If a mutation is found, then the Lynch syndrome diagnosis is confirmed. In
addition, genetic testing may then be offered to other members of the family who wish to learn
whether or not they have Lynch syndrome.
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