GNAS and obesity due to melanocortin 4 receptor deficiency: Patients with maternally derived germline GNAS mutations have been shown to develop pseudohypoparathyroidism 1A (PHP1A) with associated obesity and hormonal resistance, while those with paternally derived germline GNAS mutations have been shown to develop pseudopseudohypoparathyroidism (PPHP) without associated obesity or hormonal resistance [19].