DMF and its active metabolite MMF are also agonizts of the G-protein coupled receptor hydroxycarboxylic acid receptor 2 (HCA2, also known as niacin receptor 1 and GPR109A), which belongs to the nicotinic acid receptor family.42 HCA2 is the receptor for niacin, a form of Vitamin B3 and the precursor of the coenzymes nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP).43 Niacin is widely used in treating high blood cholesterol and pellagra. This evidence concerns the gene HCAR2 and Vitamin B3 deficiency.