The systems integration of tissue-specific molecular data also revealed many tissue- and disease-specific processes, such as liver-centric lipid metabolism and transport pathways for obesity and CVD; liver- and adipose-specific oxidative phosphorylation, fatty acid oxidation, PPAR signaling, fat cell differentiation for obesity, insulin resistance, and T2D; liver-specific glucagon signaling and islet-specific cell cycle regulation for T2D; and circadian rhythm and RNA splicing processes in brain for obesity and T2D. The gene discussed is PPARA; the disease is obesity due to melanocortin 4 receptor deficiency.