However, the interacting SNPs can also be located within different genes as in the case of Pro589Ser (rs1049296) in the transferrin (TF) gene and Cys282Tyr (rs1800562) in the haemochromatosis (HFE) gene which interact so as to increase the risk of Alzheimer disease (Robson et al. 2004; Kauwe et al. 2010). Here, TF is linked to early-onset autosomal dominant Alzheimer disease.