MSTN and obesity due to melanocortin 4 receptor deficiency: Surprisingly, Adipo-PRDM16 KO; Mstn-/- and Mstn-/- were equally (Tukey post-hoc p = 0.15) and dramatically protected from obesity compared to Adipo-PRDM16 KO and WT control mice (Tukey post-hoc p < 0.001) (Figure 2C).