AltSFPQ splicing was significantly increased in both familial ALS datasets [FUS R521G delta percent spliced in (dPSI) 0.146, P = 0.0212; SOD1 A4V dPSI 0.047, P = 4.18 × 10−5], whereas wtSFPQ splice junction usage was significantly reduced (FUS R521G dPSI −0.146, P = 0.0212; SOD1 A4V dPSI −0.378, P = 1.66 × 10−13) (Fig. 6, C and D); irSFPQ was increased in SOD1 A4V neurons (dPSI 0.323, P = 5.99 × 10−12) (fig. Here, SOD1 is linked to amyotrophic lateral sclerosis.