BAG3 and myofibrillar myopathy: Myofibrillar myopathy (MFM) is also caused by aggregation-prone mutations in proteins associated with the Z-disc [4, 10, 53, 71], including αB-crystallin, SQSTM1, and BAG3, which interact with HSPB8 to mediate chaperone-assisted-selective autophagy (CASA), a process required for the maintenance of myofibrils.