ATXN3 and Machado-Joseph disease: Soluble mutant ataxin-3 levels were measured by time-resolved Forster resonanceenergy transfer (TR-FRET) immunoassay in human cell lines and brain samples oftransgenic SCA3/MJD mice model (Nguyen etal., 2013), but properties of soluble ataxin-3 as a diseasebiomarker were not addressed up to date.