BBS2 and obesity due to melanocortin 4 receptor deficiency: In mice, loss of Bbs2, Bbs4 and Bbs6 causes hyperphagia, obesity and hyperleptinemia (Rahmouni et al., 2008), and hypothalamic neurons of Bbs4−/− mice lack ciliary localization of appetite-regulating G-protein coupled receptors (Berbari et al., 2008).