Underlying this impaired ability of the lymphatic vasculature to support functional transport, several studies have now implicated the role of iNOS and perturbed NO signaling as a mechanism related to poor lymphatic contraction observed in obesity, diabetes, and other models of metabolic syndrome (Zawieja et al., 2012; Blum et al., 2014; Scallan et al., 2015; Hespe et al., 2016; Torrisi et al., 2016). The gene discussed is NOS2; the disease is obesity due to melanocortin 4 receptor deficiency.