ERN1 and Alzheimer disease: Finally, a polymorphism in the Xbp1 promoter is one of the risk factors for Alzheimer’s disease [17] and the pathobiology of protein aggregation conditions such as Alzheimer’s and Huntington’s disease can be regulated via a modulation of the IRE1ɑ-XBP1 branch of the UPR [18, 19, 35].