Inherited susceptibility to colorectal cancer.
The principal Mendelian disorders predisposing to colorectal cancer are familial adenomatous polyposis (FAP) and hereditary nonpolyposis colorectal cancer (HNPCC). FAP is due to mutations in the APC gene. HNPCC is due to a mutation in one of at least five mismatch repair genes. Identification of individuals with these conditions is important because colon cancer will occur in approximately 80% and onset is early. For FAP, protein truncation testing will identify the vast majority of mutations. For HNPCC, 80%-95% can be identified by microsatellite instability testing. A current U.S. study reports that 12% of consecutive colorectal cancers have high microsatellite instability and that, of this 12%, 25% have detectable mutations of MLH1, MSH2, or MSH6. Potential benefits of identification include improved compliance with recommended surveillance, early detection of polyps, reduction in cancer mortality, offering of testing to relatives, and reassurance for relatives found to be negative with attendant savings in the time and expense of surveillance.
Rowley
Peter T
PT
Department of Medicine and Division of Genetics, University of Rochester, Rochester, New York 14642, USA. peter_rowley@urmc.rochester.edu
D011125:Adenomatous Polyposis Coli / Q000235:genetics*; D020137:Base Pair Mismatch / Q000235:genetics; D002471:Cell Transformation, Neoplastic / Q000235:genetics / Q000473:pathology; D015179:Colorectal Neoplasms / Q000235:genetics*; D003123:Colorectal Neoplasms, Hereditary Nonpolyposis / Q000235:genetics*; D004252:DNA Mutational Analysis; D005817:Genetic Counseling; D020022:Genetic Predisposition to Disease / Q000235:genetics*; D005820:Genetic Testing; D006801:Humans; D018895:Microsatellite Repeats; D008967:Molecular Biology