AR and Familial prostate cancer: The existence of the polyQ expansion in the AR protein also means that SBMA is the sole ligand-dependent polyQ disorder; it shares its causative protein with other diseases including androgen-insensitivity syndrome (AIS) and prostate cancer (Gottlieb et al., 2004, 2012; Beitel et al., 2013; Cortes and La Spada, 2018).