For instance, Young et al. reported that most BBS3 patients of northern European descent displayed no or mild obesity phenotype,38 whereas most BBS3 patients of Arab-Bedouin and Iranian families were found to exhibit marked obesity.39, 40 We previously reported that the phenotype developed by global Bbs3 null mice do not entirely mimic those observed in other BBS knockout mice.26 In particular, Bbs3 null mice displayed minimal increase in body weight, adiposity, and plasma leptin. This evidence concerns the gene ARL6 and obesity due to melanocortin 4 receptor deficiency.