In Alzheimer's disease, the downregulation of peroxisome proliferator‐activated receptor γ (PPARγ) and the accumulation of Aβ42 peptides in the brain correlate with a decrease in Hsp90β levels in BV2 cells in mouse models, while Hsp90α expression remains unaltered, indicating distinct roles for the two isoforms [131]. The gene discussed is HSP90AA1; the disease is early-onset autosomal dominant Alzheimer disease.