title: Association of Caucasian-identified variants with colorectal cancer risk in Singapore Chinese.
abstract: BACKGROUND
  Genome-wide association studies (GWAS) in Caucasians have identified fourteen index single nucleotide polymorphisms (iSNPs) that influence colorectal cancer (CRC) risk.
  
  
  METHODS
  We investigated the role of eleven iSNPs or surrogate SNPs (sSNPs), in high linkage disequilibrium (LD, r(2)≥ 0.8) and within 100 kb vicinity of iSNPs, in 2,000 age- and gender-matched Singapore Chinese (SCH) cases and controls.
  
  
  RESULTS
  Only iSNP rs6983267 at 8q24.21 and sSNPs rs6695584, rs11986063, rs3087967, rs2059254, and rs7226855 at 1q41, 8q23.3, 11q23.1, 16q22.1 and 18q21.1 respectively showed evidence of association with CRC risk, with odds ratios (OR) ranging from 1.13 to 1.40. sSNP rs827401 at 10p14 was associated with rectal cancer risk (OR = 0.74, 95% CI 0.63-0.88) but not disease prognosis (OR = 0.91, 95% CI 0.69-1.20). Interestingly, sSNP rs3087967 at 11q23.1 was associated with CRC risk in men (OR = 1.34, 95% CI 1.14-1.58) but not women (OR = 1.07, 95% CI: 0.88-1.29), suggesting a gender-specific role. Half of the Caucasian-identified variants, including the recently fine-mapped BMP pathway loci, BMP4, GREM1, BMP2 and LAMA 5, did not show any evidence for association with CRC in SCH (OR ~1; p-value >0.1). Comparing the results of this study with that of the Northern and Hong Kong Chinese, only variants at chromosomes 8q24.21, 10p14, 11q23.1 and 18q21.1 were replicated in at least two out of the three Chinese studies.
  
  
  CONCLUSIONS
  The contrasting results between Caucasians and Chinese could be due to different LD patterns and allelic frequencies or genetic heterogeneity. The results suggest that additional common variants contributing to CRC predisposition remained to be identified.
authors.affiliation: Department of Colorectal Surgery, Singapore General Hospital, Singapore.
authors.forename: Lai Fun
authors.initials: LF
authors.lastname: Thean
authors.forename: Hui Hua
authors.initials: HH
authors.lastname: Li
authors.forename: Yik Ying
authors.initials: YY
authors.lastname: Teo
authors.forename: Woon-Puay
authors.initials: WP
authors.lastname: Koh
authors.forename: Jian-Min
authors.initials: JM
authors.lastname: Yuan
authors.forename: Mei Lin
authors.initials: ML
authors.lastname: Teoh
authors.forename: Poh Koon
authors.initials: PK
authors.lastname: Koh
authors.forename: Choong Leong
authors.initials: CL
authors.lastname: Tang
authors.forename: Peh Yean
authors.initials: PY
authors.lastname: Cheah
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D044466:Asian People / Q000235:genetics*; D016022:Case-Control Studies; D015179:Colorectal Neoplasms / Q000235:genetics* / Q000473:pathology; D005260:Female; D020022:Genetic Predisposition to Disease; D006801:Humans; D015810:Linkage Disequilibrium / Q000235:genetics; D008297:Male; D008875:Middle Aged; D020641:Polymorphism, Single Nucleotide / Q000235:genetics*; D012307:Risk Factors; D012846:Singapore; D044465:White People / Q000235:genetics*