Maged1 is a transcriptional co-activator that has been implicated in the regulation of myogenic differentiation [30], sexual behavior [31], obesity [31] and the transcriptional function of Dlx5[32], a positive regulator of osteoblast differentiation and bone mass [33], [34]. The gene discussed is MAGED1; the disease is obesity due to melanocortin 4 receptor deficiency.