Growth curve of MC3R mutants and wild type littermates on a mixed 129; B6 background. Some of the data for this growth curve was published in the initial analysis [9]. Male and female Mc3r−/− mice (n = 9−18), heterozygotes (Mc3r+/−, n = 22−31), and wild type (Mc3r+/+, n = 9−18) mice were weaned onto mouse breeder chow (Purina 5015, 25% kJ/fat) and body weights recorder every 7–10 days.