To help define potential RAN-translation factors, we developed a gain-of-function fly model for C9orf72-associated ALS/FTD that expressed an expanded GGGGCC hexanucleotide repeat (termed G4C2) downstream of the sequence normally found upstream of the repeat in patients (114 bp of intronic DNA found 5′-prime of the repeat in intron 1 of C9orf72 in ALS/FTD); the transgene expressed also contained a GFP tag downstream of the repeat in the GR reading frame (see Fig. 1). Here, C9orf72 is linked to frontotemporal dementia.