HDAC11 is the singular HDAC isoenzyme in class IV and was the most recently discovered HDAC in 2002.86 It is the smallest of the HDAC enzymes and is a much more effective fatty-acid deacylase than a histone deacetylase.87 HDAC11 does not exhibit significant effects on cell proliferation but has been noted as a potential target for metabolic disorders.88 Selective inhibitors of HDAC11 have been reported,89 however as of yet, at the time of writing, no PROTACs targeting HDAC11 for degradation have been reported. This evidence concerns the gene HDAC9 and metabolic disease.