The effects of MCP-1 in recruiting monocytes, T lymphocytes and natural killer cells are dependent of the C-C motif chemokine receptor (CCR2), since the use of a specific antagonist for this receptor attenuates obesity-induced macrophage accumulation (Charo and Taubman, 2004; Weisberg et al., 2006; Gonzalez-Quesada and Frangogiannis, 2009). The gene discussed is CCR2; the disease is obesity due to melanocortin 4 receptor deficiency.