title: Allelic imbalance at rs6983267 suggests selection of the risk allele in somatic colorectal tumor evolution.
abstract: A common single nucleotide polymorphism (SNP), rs6983267, at 8q24.21 has recently been shown to associate with colorectal cancer (CRC). Three independent SNP association studies showed that rs6983267 contributes to CRC with odds ratios (OR) of 1.17 to 1.22. Here, we genotyped a population-based series of 1,042 patients with CRC and 1,012 healthy controls for rs6983267 and determined the contribution of SNP to CRC in Finland, using germ line DNA, as well as the respective cancer DNA in heterozygous patients. The comprehensive clinical data available from the 1,042 patients and their first-degree relatives enabled us to thoroughly examine the possible association of this variant with different clinical features. As expected, a significant association between the G allele of rs6983267 and CRC [OR, 1.22; 95% confidence interval (CI), 1.08-1.38; P = 0.0018] was found, confirming the previous observations. A trend towards association of the G allele with microsatellite-stable cancer (OR, 1.37; 95% CI, 1.02-1.85; P = 0.04) and family history of cancers other than CRC was seen (OR, 1.20; 95% CI, 1-1.43; P = 0.05). Four hundred and sixty-six GT heterozygotes identified in this study were analyzed for allelic imbalance at rs6983267 in the respective cancer DNA. One hundred and one tumors showed allelic imbalance (22%). The risk allele G was favored in 67 versus 34 tumors (P = 0.0007). This finding implicates that the underlying germ line genetic defect in 8q24.21 is a target in the somatic evolution of CRC.
authors.affiliation: Department of Medical Genetics, Genome-Scale Biology Research Program, Biomedicum Helsinki, University of Helsinki, P.O. Box 63, FIN-00014 Helsinki, Finland.
authors.forename: Sari
authors.initials: S
authors.lastname: Tuupanen
authors.forename: Iina
authors.initials: I
authors.lastname: Niittymäki
authors.forename: Kari
authors.initials: K
authors.lastname: Nousiainen
authors.forename: Sakari
authors.initials: S
authors.lastname: Vanharanta
authors.forename: Jukka-Pekka
authors.initials: JP
authors.lastname: Mecklin
authors.forename: Kyösti
authors.initials: K
authors.lastname: Nuorva
authors.forename: Heikki
authors.initials: H
authors.lastname: Järvinen
authors.forename: Sampsa
authors.initials: S
authors.lastname: Hautaniemi
authors.forename: Auli
authors.initials: A
authors.lastname: Karhu
authors.forename: Lauri A
authors.initials: LA
authors.lastname: Aaltonen
mesh_terms: D000368:Aged; D000483:Alleles; D022981:Allelic Imbalance; D002898:Chromosomes, Human, Pair 8 / Q000235:genetics*; D015179:Colorectal Neoplasms / Q000235:genetics*; D004273:DNA, Neoplasm; D019143:Evolution, Molecular; D005260:Female; D005387:Finland; D006579:Heterozygote; D006801:Humans; D008297:Male; D008875:Middle Aged; D020641:Polymorphism, Single Nucleotide; D012306:Risk; D012641:Selection, Genetic; D017422:Sequence Analysis, DNA; D044465:White People / Q000235:genetics
chemical_list: D004273:DNA, Neoplasm