MAPT and juvenile Huntington disease: In neurodegenerative diseases, FKBP51 promotes aberrant aggregation of Tau protein via the HSP90 complex, exacerbating the pathological progression of Alzheimer’s disease; in Parkinson’s disease, it influences neuronal survival through interaction with the PINK1/AKT signaling pathway; while in Huntington’s disease, it impairs the clearance of mutant huntingtin (mHTT) protein.