ACSS2, which is highly expressed in patients with obesity-induced myeloma, converts acetic acid to acetyl-CoA, and lysine acetyl-transferase-binding protein (CBP) transfers the acetyl group from acetyl coenzyme A, which is mediated by the ACSS2 generation of acetic acid, to IRF4, resulting in the acetylation of IRF4 at K399. Here, ACSS2 is linked to obesity due to melanocortin 4 receptor deficiency.