The group of Zorzano showed that decreased expression of Mfn2 and altered expression of OPA1 participated in obesity and type 2 diabetes development in both patients and rodent models (Bach et al., 2003; Zorzano et al., 2009a,b, 2010; Hernández-Alvarez et al., 2010; Quirós et al., 2012). The gene discussed is MFN2; the disease is obesity due to melanocortin 4 receptor deficiency.