Who Should Have Genetic Testing for the Lynch Syndrome?

open here please ►Who Should Have Genetic Testing for the Lynch Syndrome?: "* Editorial

Who Should Have Genetic Testing for the Lynch Syndrome?

1. Randall W. Burt, MD

+ Author Affiliations

1. From University of Utah and Huntsman Cancer Institute, Salt Lake City, UT 84112.

Determining who should have genetic testing for the Lynch syndrome remains problematic. The inherited polyposis syndromes usually exhibit characteristic phenotypes to guide initial genetic testing in a family. But distinctive features of the Lynch syndrome are seldom apparent in individual patients (1). Thus, the syndrome is usually suspected on the basis of a strong family history of colon cancer and other types of cancer.

The Amsterdam criteria were developed to identify persons and families who are likely to have the syndrome. The criteria include the following: 3 relatives in a family must have colorectal cancer, and 2 of them must be first-degree relatives of the third; at least 2 generations must be affected; and 1 of the cases must be diagnosed at an age younger than 50 years (2). These criteria have been successfully used to identify families with the Lynch syndrome but have also proven to be insensitive. At least 50% of families with the condition do not meet the criteria. About one half of families meeting the criteria will have a disease-causing mutation in one of the mismatch repair genes ( MLH1, MSH2, MSH6, or PMS2). Finding a mutation confirms the diagnosis and allows mutation-specific testing to be done in other family members. The Amsterdam II criteria are the same as the Amsterdam criteria, except that any of the other types of Lynch syndrome–associated cancer including uterine, gastric, ovarian, pancreatic, biliary, renal, and urinary tract cancer can be substituted for colon cancer (3). As one would expect, the Amsterdam II criteria are more sensitive, but …

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