In C9ORF72-associated ALS/FTD, the RNA polymerase II-associated factor 1 (PAF1) complex and transcription elongation factor SUPT4H1 (suppressor of Ty 4 homolog 1) promote bidirectional transcription from C9ORF72-associated repeats [13,14]. Here, SUPT4H1 is linked to frontotemporal dementia.