ARL6 and obesity due to melanocortin 4 receptor deficiency: Interestingly, Bbs3 gene null mice do not phenocopy many of the features displayed by BBSome-deficient mice.26 In particular, Bbs3 null mice exhibited a modest increase in body weight and fat mass whereas mice lacking elements of the BBSome display overt obesity and associated diseases including type 2 diabetes.11, 21, 27, 28 These results suggest that BBSome regulation of body weight and energy homeostasis is not related to its function in cilia.