In individuals with obesity or diabetes, circulating levels of GDF-15 are higher than in unaffected individuals [10–12], and are positively correlated with blood concentrations of glucose, HbA1c, insulin resistance, C-reactive protein (CRP) and other cardiovascular risk factors [10, 11, 13]. The gene discussed is GDF15; the disease is obesity due to melanocortin 4 receptor deficiency.