An alternative hypothesis is that different CE-containing transcripts may be vulnerable in the different phenotypic presentations of the C9ORF72 mutation, with KALRN CEs being more specific to an FTD presentation of disease, although the KALRN CE was recently identified in an analysis of ALS patient postmortem spinal cord [63], thus further investigation is required to explore this hypothesis. Here, KALRN is linked to frontotemporal dementia.