title: Sequence variants of interleukin 6 (IL-6) are significantly associated with a decreased risk of late-onset Alzheimer's disease.
abstract: BACKGROUND
  Interleukin 6 (IL-6) has been related to beta-amyloid aggregation and the appearance of hyperphosphorylated tau in Alzheimer's disease (AD) brain. However, previous studies relating IL-6 genetic polymorphisms to AD included few and unrepresentative single nucleotide polymorphisms (SNPs) and the results were inconsistent.
  
  
  METHODS
  This is a case-control study. A total of 266 patients with AD, aged≧65, were recruited from three hospitals in Taiwan (2007-2010). Controls (n = 444) were recruited from routine health checkups and volunteers of the hospital during the same period of time. Three common IL-6 haplotype-tagging SNPs were selected to assess the association between IL-6 polymorphisms and the risk of late-onset AD (LOAD).
  
  
  RESULTS
  Variant carriers of IL-6 rs1800796 and rs1524107 were significantly associated with a reduced risk of LOAD [(GG + GC vs. CC): adjusted odds ratio (AOR) = 0.64 and (CC + CT vs. TT): AOR = 0.60, respectively]. Haplotype CAT was associated with a decreased risk of LOAD (0 and 1 copy vs. 2 copies: AOR = 0.65, 95% CI = 0.44-0.95). These associations remained significant in ApoE e4 non-carriers only. Hypertension significantly modified the association between rs2069837 polymorphisms and the risk of LOAD (pinteraction = 0.03).
  
  
  CONCLUSIONS
  IL-6 polymorphisms are associated with reduced risk of LOAD, especially in ApoE e4 non-carriers. This study identified genetic markers for predicting LOAD in ApoE e4 non-carriers.
authors.affiliation: Institute of Epidemiology and Preventive Medicine, College of Public Health, National Taiwan University, Taipei, Taiwan.
authors.forename: Shih-Yuan
authors.initials: SY
authors.lastname: Chen
authors.forename: Ta-Fu
authors.initials: TF
authors.lastname: Chen
authors.forename: Liang-Chuan
authors.initials: LC
authors.lastname: Lai
authors.forename: Jen-Hau
authors.initials: JH
authors.lastname: Chen
authors.forename: Yu
authors.initials: Y
authors.lastname: Sun
authors.forename: Li-Li
authors.initials: LL
authors.lastname: Wen
authors.forename: Ping-Keung
authors.initials: PK
authors.lastname: Yip
authors.forename: Yi-Min
authors.initials: YM
authors.lastname: Chu
authors.forename: Yen-Ching
authors.initials: YC
authors.lastname: Chen
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000150:complications / Q000453:epidemiology / Q000235:genetics*; D053327:Apolipoprotein E4 / Q000235:genetics; D016022:Case-Control Studies; D005260:Female; D005787:Gene Frequency; D020022:Genetic Predisposition to Disease; D005838:Genotype; D006801:Humans; D015850:Interleukin-6 / Q000235:genetics*; D015810:Linkage Disequilibrium; D008297:Male; D008609:Mental Status Schedule; D020641:Polymorphism, Single Nucleotide / Q000235:genetics*; D012189:Retrospective Studies; D012307:Risk Factors; D013624:Taiwan / Q000453:epidemiology
chemical_list: D053327:Apolipoprotein E4; D015850:Interleukin-6