Iron genes, iron load and risk of Alzheimer's disease

Background: Compound heterozygotes of the haemochromatosis gene (HFE) variants, H63D and C282Y, have raised transferrin saturation compared with that in the wild type. In the cohort of the Oxford Project To Investigate Memory and Ageing (OPTIMA), bicarriers of the HFE C282Y and the transferrin C2 gene variants are at five times greater risk of developing Alzheimer's disease; the addition of HFE H63D may raise the risk still further. Objective: To investigate transferrin saturation by HFE and transferrin genotype among people without dementia-that is, controls and those with mild cognitive impairment (MCI) and also among those with Alzheimer's disease. Methods: Serum iron status and genotype were examined of 177 patients with Alzheimer's disease, 69 patients with MCI and 197 controls from the OPTIMA cohort. Results: Although each of these variants alone had relatively little effect on iron status, the combination of either HFE C282Y and HFE H63D or of HFE C282Y and transferrin C2 markedly raised transferrin saturation in those without dementia, but had little effect in those with mature Alzheimer's disease. Conclusions: These combinations may raise the risk for Alzheimer's disease, owing to higher iron loads and therefore oxidative stress in the preclinical phase. If replicated, these findings will have implications for the prevention of Alzheimer's disease.