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. © 2012 Elsevier B.V. All rights reserved.