GNAS and obesity due to melanocortin 4 receptor deficiency: Though, Fatq2b has several genes involved in energy metabolism, protein transport and GTP cell signaling; analyses of gene expression in five genes suggests Rab22a as candidates, and the obesity phenotype of the Gnas knockout suggests these two genes as strong candidates for Fatq2b, though further analyses are required to confirm and ascertain the biological mechanisms of these genes in order to understand how Fatq2b exerts its effects on body fat.