THE APC GENE I1307K VARIANT IS RARE IN NORWEGIAN PATIENTS WITH FAMILIAL AND SPORADIC COLORECTAL OR BREAST-CANCER

Recently, a T-to-A transversion creating an 8-base mononucleotide trac t in the APC gene, resulting in substitution of lysine for isoleucine at codon 1307 (11307K), was found in a subset of Ashkenazi Jews. This sequence variant was most frequent in colorectal cancer patients with a positive family history of colorectal cancer. To determine whether t he 11307K variant plays a role in colorectal or breast cancer predispo sition in the Norwegian population, we have analyzed blood samples fro m 210 colorectal cancer patients and 183 breast cancer patients by PCR and direct sequencing. Thirty-seven of the colorectal cancer patients had a positive family history of cancer. Among the breast cancer pati ents, 24 had a family history of colorectal cancer and 75 a family his tory of breast and/or ovarian cancer. Only one colorectal cancer patie nt who belonged to a Jewish family was found to carry the A variant. O ur data show that the 11307K variant is rare in the Norwegian populati on and should not be viewed as a candidate for susceptibility testing for colorectal cancer.