We have previously shown that C1q/tumor necrosis factor (TNF)-related protein 6 (CTRP6; also known as C1qtnf6)—a secreted protein of the C1q family (23, 24)—is one of the autocrine and paracrine factors that regulates macrophage function in obesity (25). This evidence concerns the gene C1QTNF6 and obesity due to melanocortin 4 receptor deficiency.