CKS1B and Miyoshi myopathy: More recently, “double hit” MM, defined as bi-allelic TP53 inactivation or amplification (> 4 copies) of CKS1B (1q21) on a background of ISS stage 3, has been identified, constituting ~ 6% of newly diagnosed MM and carries a markedly poor prognosis with median PFS and OS being 15 months and 21 months, respectively [76].