Constitutional (also known as germline) variants are present in all the body’s cells, including the germ cells, and can therefore be passed on to offspring; somatic variants arise during an individual’s lifetime in tissues other than the germ cells and so are not passed on.
The identification of a germline variant in a mismatch repair (MMR) gene in a patient with colorectal cancer has implications for the clinical management of the current cancer and the patient’s future cancer risk. It should also trigger cascade screening in the wider family.
(Cascade testing is the process of informing family members of a genetic condition discovered within the family, followed by family members getting tested for the condition.)
Lynch Syndrome Ireland 