REG1B and obesity due to melanocortin 4 receptor deficiency: This analysis showed that some proteins, such as COL1A1, COL6A3, FABP4, LEP, LGALS1, and THBS4, are obesity-specific, and GDF15, LPL, MCFD2, REG1A, REG1B, and TCN2 are T2D-specific (Figure S1).