Synergistic effect of heme oxygenase-1 and tau genetic variants on Alzheimer's disease risk.

Oxidative stress plays a role in tau hyperphosphorylation and the development of neurofibrillary tangles (NFT). In Alzheimer's disease (AD) brain, accumulation of hyperphosphorylated tau in NFT is associated with the induction of heme oxygenase-1 (HO-1), a potent antioxidant that downregulates the production of tau. In a case-control study of 300 AD patients and 360 healthy controls, we examined whether the combined gene effects between HO-1 (-413, rs2071746) and tau (5' of exon 1, rs242557) polymorphisms might be responsible for susceptibility to AD. Subjects carrying both the HO-1 (-413) TT and the tau (5' of exon 1) AA genotypes had a more than 6.5-time higher risk of developing AD than subjects without these risk genotypes (OR = 6.65, 95% CI 1.12-39.29; p = 0.037). These data support a role for tau-related genes in the risk of AD. Copyright 2008 S. Karger AG, Basel.