Members of the serum amyloid A (SAA) family are acute phase reactants and chemokines that are elevated in acute inflammatory conditions such as infection (1, 2), as well as chronic inflammatory conditions including autoimmune disorders (3–8), obesity (9–13), type 2 diabetes (T2D) (14, 15), and cardiovascular disease (CVD) (16–19) (reviewed extensively in 20, 21). Here, SAA2 is linked to obesity due to melanocortin 4 receptor deficiency.