<unk>  is an epigenetic modification to the DNA packaging protein histone H4. It is a mark that indicates the acetylation at the 91st lysine residue of the histone H4 protein. No known diseases are attributed to this mark but it might be implicated in melanoma.
H4K91ac
H4K8ac
H4K12ac
H4K5ac
H3K9ac
H3K14ac
H3K23ac
H3K56ac