Covalent modifications of histones are a crucial component of epigenetic events that regulate chromatin structures and gene function. Evidence exists that distinct lysine residues in histones are modified by covalent attachment of the vitamin biotin, catalyzed by biotinidase and holocarboxylase synthetase. Biotinylation of histones appears to be conserved across species. The following biotinyla...

Multiple carboxylase deficiency (MCD) is a rare inherited metabolic disease of biotin dependency due to deficiency of holocarboxylase synthetase (HCS) or biotinidase deficiency. A 30-month-old female patient who presented with the initial features of diabetic ketoacidosis (severe metabolic acidosis, ketosis, and hyperglycemia), lactic acidemia, moderate hyperammonemia, and generalized organic a...