When is molecular genetic testing for colorectal cancer indicated?
The genetic mutations causing many of the syndromes which confer a high inherited risk of colorectal cancer have now been identified. These include familial adenomatous polyposis, hereditary non-polyposis colorectal cancer, Peutz-Jeghers syndrome, Cowden's syndrome and juvenile polyposis. In all these diseases, the precise mutation is nearly always unique to a particular family; there are few mutation hot spots. This means that mutation detection is technically demanding. Nonetheless, genetic testing can now be used clinically to confirm the diagnosis in affected individuals, and to predict whether an "at risk" family member has inherited the disease and should therefore have endoscopic screening. Because current technology does not detect all mutations, a negative result in a definitely affected individual is diagnostically unhelpful and does not allow predictive testing of other family members. When a mutation can be detected, it is diagnostically very useful, and allows better management of all family members.
Leggett
Barbara
B
Clinical Research Centre of the Royal Brisbane Hospital Research Foundation, Bancrift Centre, Herston 4029, Brisbane, Australia. barbara_leggett@health.qld.gov.au
D011125:Adenomatous Polyposis Coli / Q000235:genetics; D015179:Colorectal Neoplasms / Q000235:genetics*; D005817:Genetic Counseling; D006223:Hamartoma Syndrome, Multiple / Q000235:genetics; D006801:Humans; D007417:Intestinal Polyps / Q000235:genetics; D008967:Molecular Biology / Q000379:methods*