AR and neurodegenerative disease: Spinal and bulbar muscular atrophy (SBMA) is an X‐linked, intractable, adult‐onset neurodegenerative disease caused by the expansion of a CAG repeat within the first exon of the androgen receptor (AR) gene (Kennedy et al, 1968; Sobue et al, 1989; Finsterer & Soraru, 2016), and the toxic function gained from the mutant AR in both spinal motor neurons and skeletal muscle underlies the pivotal SBMA pathomechanism (Katsuno et al, 2012a,b; Giorgetti & Lieberman, 2016; Pennuto & Basso, 2016).