RanGAP1 plays a key role in maintaining the nucleo/cytoplasmic gradient of Ran-GTP/GDP that drives active nuclear transport, and mislocalization of this protein occurs in numerous cell and animal models of ALS and HD, as well as in C9orf72 and HD patient brain tissue74,76–79. This evidence concerns the gene C9orf72 and amyotrophic lateral sclerosis.