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

BackgroundThe 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.MethodsA meta-analysis was carried out to analyze the association between the M/V polymorphism in the PRNP gene and the risk of AD.ResultsA 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).ConclusionsOur results suggest that the M/V polymorphism in the PRNP gene contributes to the susceptibility of Alzheimer disease.