HDAC9 and amyotrophic lateral sclerosis: There is evidence of decreased histone acetylation in ALS tissue and experimental models.16, 31, 32, 33, 34, 35 We previously reported that H3/H4 histone acetylation, associated with active chromatin, was reduced in cultured motor neurons expressing a fALS-linked FUS variant and was prevented by treatment with the pan HDAC inhibitor, SAHA.35