C9orf72 and amyotrophic lateral sclerosis: Motoneurons derived from induced pluripotent stem cells (iPS cells) from ALS patients, harboring SOD1, C9orf72, and fused-in-sarcoma (FUS) mutations, have been reported to display reduced delayed-rectifier K+ current (Kv7 or M-current) amplitudes relative to control-derived motor neurons [91].