Inherited colorectal polyposis and cancer risk of the APC I1307K polymorphism.
Germ-line and somatic truncating mutations of the APC gene are thought to initiate colorectal tumor formation in familial adenomatous polyposis syndrome and sporadic colorectal carcinogenesis, respectively. Recently, an isoleucine-->lysine polymorphism at codon 1307 (I1307K) of the APC gene has been identified in 6%-7% of the Ashkenazi Jewish population. To assess the risk of this common APC allelic variant in colorectal carcinogenesis, we have analyzed a large cohort of unselected Ashkenazi Jewish subjects with adenomatous polyps and.or colorectal cancer, for the APC I1307K polymorphism. The APC I1307K allele was identified in 48 (10.1%) of 476 patients. Compared with the frequency in two separate population control groups, the APC I1307K allele is associated with an estimated relative risk of 1.5-1.7 for colorectal neoplasia (both P=.01). Furthermore, compared with noncarriers, APC I1307K carriers had increased numbers of adenomas and colorectal cancers per patient (P=.03), as well as a younger age at diagnosis. We conclude that the APC I1307K variant leads to increased adenoma formation and directly contributes to 3%-4% of all Ashkenazi Jewish colorectal cancer. The estimated relative risk for carriers may justify specific clinical screening for the 360,000 Americans expected to harbor this allele, and genetic testing in the setting of long-term-outcome studies may impact significantly on colorectal cancer prevention in this population.
Gryfe
R
R
Centre for Cancer Genetics, Samuel Lunenfeld Research Institute, Mount Sinai Hospital, Toronto, Canada M5G 1X5.
Di Nicola
N
N
Lal
G
G
Gallinger
S
S
Redston
M
M
D011125:Adenomatous Polyposis Coli / Q000235:genetics*; D025601:Adenomatous Polyposis Coli Protein; D000368:Aged; D003110:Colonic Neoplasms / Q000235:genetics*; D003598:Cytoskeletal Proteins / Q000235:genetics*; D005260:Female; D030342:Genetic Diseases, Inborn; D006801:Humans; D008297:Male; D010190:Pancreatic Neoplasms / Q000235:genetics; D011110:Polymorphism, Genetic; D012307:Risk Factors