XBP1 and Miyoshi myopathy: The aim of our study was to evaluate the prognostic value of nine previously described genes that may affect the prognosis in patients with a clinically detected loss of response to bortezomib treatment: ABCB1, CXCR4, MAF, MARCKS, POMP, PSMB5, RPL5, TXN, and XBP1. A better understanding of the genetic disorders involved in MM drug resistance can improve the prognosis and prognostication, and assist the development of new therapeutic options to improve the treatment of this disease.