While the consequences on H3K27me3 levels have not been reported, transcriptomic analyses conducted on post-mortem brains from C9-ALS/FTD patients have unraveled the de-repression of PRC2-target genes, suggesting that C9-mediated neurodegeneration likely involves epigenetic dysregulations, in addition to the production of toxic RNA and DPRs and loss of function [99,100,101] (Table 2). Here, C9 is linked to frontotemporal dementia.