C9orf72 and frontotemporal dementia: Healthy individuals possess ≤ 11 GGGGCC repeats in C9orf72 (Rutherford et al., 2012; Harms et al., 2013; van der Zee et al., 2013), whereas hundreds to thousands of repeats are present in ALS/FTD patients (Beck et al., 2013; Harms et al., 2013; van Blitterswijk et al., 2013; Suh et al., 2015).