In vitro, leptin induces cardiomyocyte hypertrophy (Xu et al., 2004; Zeidan et al., 2011) involving MAPK and RhoA-GTP (Madani et al., 2006; Zeidan et al., 2006; Zeidan et al., 2008), which contribute to morphological and phenotypic changes in cardiac size, structure, function, and heart failure (Sweeney, 2010). The gene discussed is LEP; the disease is heart failure.