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

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.