Similarly, Brs3, bombesin-like receptor 3, at 57 Mb on chromosome X, is a possible candidate for our proximal X obesity QTL since mice with mutations at this locus exhibit obesity, an impaired glucose metabolism, and a reduced metabolic rate (Ladenheim et al., 2008). The gene discussed is BRS3; the disease is obesity due to melanocortin 4 receptor deficiency.