A gain of toxic function of the mutated RNA was first reported in a study concerning DM1 and subsequently reported for other pathologies, such as HDL2, SCA8, 10, 31, FXTAS, and more recently, FTD, amyotrophic lateral sclerosis (ALS), mixed ALS/FTD cases, and SCA36 [reviewed in La Spada and Taylor (2010), DeJesus-Hernandez et al. (2011), Renton et al. (2011), Wojciechowska and Krzyzosiak (2011), Garcia-Murias et al. (2012), Ikeda et al. (2012), Simon-Sanchez et al. (2012)]. The gene discussed is JPH3; the disease is frontotemporal dementia.