We previously generated iPSC lines from control and C9-ALS fibroblasts [37], which express C9orf72 transcripts about three times more than skin fibroblasts (S4 Table), and are therefore more suitable for RNA-seq analysis (see Materials and Methods section for the methodology of analysis of relative RNA levels of introns). This evidence concerns the gene C9orf72 and amyotrophic lateral sclerosis.