In striking contrast, the presence of the hexanucleotide repeat expansion in C9ORF72-ALS patients triggers the nuclear export of C9ORF72 repeat transcripts retaining intron-1 (Fig. 8h) consistent with our previous data showing that the sequestration of SRSF1 on synthetic hexanucleotide repeat expansions promotes nuclear mRNA export through the interaction with NXF1 (Fig. 6). Here, C9orf72 is linked to amyotrophic lateral sclerosis.