C9orf72 and amyotrophic lateral sclerosis: Comparing the number of gene fusions per post-mortem sample in each ALS genetic group with controls, revealed significantly greater numbers of gene fusions in sporadic ALS (p = 8.2 × 10−6), C9orf72 (p = 0.03) and SOD1 mutant subgroups (p = 0.0009; Fig. 6h).