FASN and obesity due to melanocortin 4 receptor deficiency: When the obesity causal genes were overlapped with the fasted and fed networks, 7 genes (ADA, BBS5, CBL, CCND3, FASN, FTO and SCARB1) overlapped with PER1's downstream genes in the fed network (Fisher's Exact Test p-value = 0.037) (shown in Figure 3C).