C3AR1 and obesity due to melanocortin 4 receptor deficiency: In mice, by CIT analysis and validation studies using genetically engineered animals, Zfp90 (zinc finger protein 90), C3ar1 (complement component 3a receptor 1) and Tgfbr2 (transforming growth factor, beta receptor II) have been identified as new QTGs involved in susceptibility to obesity [33].