GNAS and obesity due to melanocortin 4 receptor deficiency: CNS-specific Gsα deficiency (mBrGsKO) does lead to obesity, but this is associated with reduced energy expenditure rather than hyperphagia, and is also associated with impaired glucose metabolism, impaired cold tolerance, and reduced blood pressure (18), none of which were observed in PVNGq/11KO or MC4RF51L mice (Table 2).