Given that HDAC inhibitors were shown to reverse some of the phenotypes in the LSDs Niemann Pick type C and Gaucher disease11,13,48, we tested the potential therapeutic effects of HDAC inhibition in fibroblasts derived from patients with sialidosis, a rare neurosomatic LSD caused by mutations in the NEU1 gene49. This evidence concerns the gene HDAC9 and sialidosis.