Comparing the number of gene fusions per iPSMN in each ALS genetic group with their respective dataset controls, revealed significantly greater numbers of gene fusions in C9orf72 (p = 0.002) and SOD1 mutant groups (p = 0.0003) as well as nonsignificant increases in sporadic (p = 0.26), TARDBP (p = 0.17) and FUS mutants (p = 0.54; Fig. 6f). Here, SOD1 is linked to amyotrophic lateral sclerosis.