UASt regulates expression of short (12 or fewer) repeats of GGGGCC (G4C2), which is used as a control - expanded repeats of GGGGCC within the first intron of Hsap\C9orf72 are the most prominent mutation in familial Amyotrophic Lateral Sclerosis (ALS) and Frontotemporal Degeneration (FTD). This construct also contains the 114-base pair sequence immediately upstream of the repeat in intron 1 of Hsap\C9orf72 in ALS/FTD patient genomes (termed a "leader" sequence; LDS). G4C2 expansions can produce three sense-strand associated dipeptides (GA, GR, and GP), and a GFP tag (lacking an ATG initiation codon) is included 3' of the repeat in the GR-reading frame.