C9orf72 and myotonic dystrophy type 2: Despite the unusual pathomechanism of disease, C9orf72 holds similarities with other expansion diseases (Rodriguez and Todd, 2019), such as Myotonic Dystrophy type 1 (DM1), Myotonic Dystrophy type 2 (DM2; Figure 2), and Friedreich ataxia (FA; Nguyen et al., 2019; Table 2).