C9orf72 and amyotrophic lateral sclerosis: Consistent with prior studies, retained introns in all three datasets (i.e. VCP, C9orf72 and SOD1 mutant ALS astrocytes) exhibited significantly shorter lengths, higher GC content, higher conservation score, higher predicted binding affinities to RNA-binding proteins (RBPs) and lower splice site strength compared with spliced introns (Supplementary Figure S4A) (36,73–74).