SELENON and multiminicore myopathy: Around 50% of MmD cases, mostly classical (Jungbluth et al., 2018), are caused by mutation in SELENON (Box 3) (Ferreiro et al., 2002a), which encodes selenoprotein N. This glycoprotein regulates Ca2+ signaling and is involved in antioxidant pathways (Box 3) (Ferreiro et al., 2002a; Pitts and Hoffmann, 2018), and has a roles in embryogenesis (Castets et al., 2009) and myogenesis (Castets et al., 2011).