These studies also demonstrated that CHI3L1 is increased in the circulation of patients who are older than 60 years of age and patients with a variety of comorbid diseases, including obesity, cardiovascular disease, kidney disease, diabetes, chronic lung disease, and cancer (Dela Cruz et al., 2012; Garnero et al., 2005; Hakala et al., 1993; Johansen et al., 2000; Johansen et al., 1993; Kucur et al., 2007; Lee, 2009; Lee et al., 2011; Lee and Elias, 2010; Matsuura et al., 2011; Nordenbaek et al., 1999; Ostergaard et al., 2002). The gene discussed is CHI3L1; the disease is obesity due to melanocortin 4 receptor deficiency.