Methods for identification of genetic modifiers and for treating nucleotide repeat disorder

The present disclosure relates to a method of identifying a genetic modifier of a nucleotide repeat disorder, comprising selecting from the subjects the late-onset subjects with higher nucleotide repeat load or the early-onset subjects with lower nucleotide repeat load and identifying one or more genetic modifiers delaying or promoting onset of a nucleotide repeat disorder. The present disclosure also relates to a method for treating or preventing a polyglutamine (polyQ) expansion disease in a subject in need of such treatment or prevention, comprising administering an effective amount of a PIAS1 variant or a recombinant nucleic acid molecule encoding the PIAS1 variant to the subject. The present disclosure also relates to a method for treating or preventing early symptom onset of the polyglutamine expansion disease, a PIAS1 variant, comprising one or more sequence changes located in the C-terminal region of PIAS1 and a recombinant nucleic acid molecule encoding the PIAS1 variant as disclosed herein.