C9orf72 and amyotrophic lateral sclerosis: In this case 20 genes have been linked to f-ALS, with chromosome 9 open reading frame 72 (C9orf72) (40%), superoxide dismutase 1 (SOD1) (20%), focused ultrasound (FUS) (1–5%), and transactive response DNA binding protein (TARDBP) (1–5%) being the primary genes responsible for the majority of f-ALS cases [13].