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Genetic testing for HNPCC may have significant meaning not only for the individual initially tested, but also for his/her family members. Gene mutations in MLH1, MSH2, or MSH6 that cause HNPCC are passed on in families in an autosomal dominant pattern . This means that an individual with a gene mutation has a 50% (or 1 in 2) chance of passing that mutation on to each of his or her offspring. Most of the time, an individual inherited their mutation from a parent. Knowing if the mutation came from the mother or father is helpful, because other, more distant family members on that side of the family (aunts, uncles, cousins, etc.) may also carry the mutation.
It is important to share genetic test results with family members. For example, a positive result indicates that other family members may also carry the mutation. Relatives have the option of being tested for the identified mutation so they can make informed decisions about screening and management that can help them prevent cancer or identify cancer at an earlier, more treatable stage. Undergoing genetic testing is a personal decision and individual family members may differ in their viewpoints and reactions to genetic testing.
» Mutation Prevalence Tables for HNPCC Genes
A genetic test for hereditary nonpolyposis
colorectal cancer (HNPCC) |
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