Changes in circulating levels of hyaluronic acid (HA), transforming growth factor (TGF)-β, chitinase 3-like (Chi3L1, also known as YKL40), lysyl oxidase-like 2 (LOXL2), and soluble ST2 (sST2) have been observed in obesity, insulin resistance, MetS and liver disease in HIV-uninfected persons, and may be useful biomarkers to detect and monitor these co-morbidities [17–22]. The gene discussed is CHI3L1; the disease is obesity due to melanocortin 4 receptor deficiency.