C3 and obesity due to melanocortin 4 receptor deficiency: Out of these, 12 proteins showed statistically significant differences in abundance between control cats and cats with obesity, namely Ig-like domain-containing protein, Alpha-2-HS-glycoprotein, Complement C8 gamma chain, An-tithrombin-III, Serpin family A member 1, Complement factor H, C3-beta-c, Albumin, C4b-binding protein alpha chain, Alpha-1-B glycoprotein, Solute carrier family 12 member 4, and Fibronectin.