title: The association between the methionine/valine (M/V) polymorphism (rs1799990) in the PRNP gene and the risk of Alzheimer disease: an update by meta-analysis.
abstract: BACKGROUND
  The M/V polymorphism in the PRNP gene has been extensively examined for the association to the risk of Alzheimer disease (AD); however, results from different studies have been inconsistent. The aim of this study is to evaluate the association between the M/V polymorphism in the PRNP gene and the risk of AD.
  
  
  METHODS
  A meta-analysis was carried out to analyze the association between the M/V polymorphism in the PRNP gene and the risk of AD.
  
  
  RESULTS
  A total of 4228 cases and 4324 controls in 16 case-control studies were included in the meta-analysis. The results indicated that the variant V allele carriers (VV+MV) had a 13% decreased risk of AD, when compared with the homozygote MM (VV+MV vs. MM: OR=0.87, 95% CI=0.79-0.96, P=0.004). In the subgroup analysis by ethnicity, significant decreased risks of AD were found in the Caucasian V allele carriers (OR=0.85, 95% CI=0.77-0.94, P=0.002), but not in Asian V allele carriers (OR=1.11, 95% CI=0.78-1.57, P=0.57). In the subgroup analysis by age of onset, significant decreased risks of AD were associated with V allele carriers in late-onset Alzheimer disease (OR=0.76, 95% CI=0.62-0.93, P=0.007) but not in early-onset Alzheimer disease (OR=0.86, 95% CI=0.70-1.06, P=0.17).
  
  
  CONCLUSIONS
  Our results suggest that the M/V polymorphism in the PRNP gene contributes to the susceptibility of Alzheimer disease.
authors: West China Medical School/West China Hospital, Sichuan University, Chengdu, Sichuan, 610041, China.
authors: Jie
authors: J
authors: He
authors: Xiaoyan
authors: X
authors: Li
authors: Jiqiao
authors: J
authors: Yang
authors: Jichong
authors: J
authors: Huang
authors: Xiaowei
authors: X
authors: Fu
authors: Yonggang
authors: Y
authors: Zhang
authors: Hong
authors: H
authors: Fan
mesh_terms: D000544:Alzheimer Disease / Q000175:diagnosis / Q000235:genetics*; D016022:Case-Control Studies; D056726:Genetic Association Studies / Q000379:methods; D020022:Genetic Predisposition to Disease / Q000235:genetics*; D006801:Humans; D008715:Methionine / Q000235:genetics*; D011110:Polymorphism, Genetic / Q000235:genetics*; D000072002:Prion Proteins; D011328:Prions / Q000235:genetics*; D014633:Valine / Q000235:genetics*
chemical_list: C512656:PRNP protein, human; D000072002:Prion Proteins; D011328:Prions; D008715:Methionine; D014633:Valine