In addition to these skeletal features, patients with GNAS mutations on the maternally inherited allele develop pseudohypoparathyroidism type 1A (PHP1A), in which patients exhibit obesity and resistance to multiple hormones requiring Gαs-coupled receptors [such as parathyroid hormone (PTH), thyrotropin (TSH), luteinizing hormone (LH), follicle-stimulating hormone (FSH), calcitonin, glucagon, and growth hormone releasing hormone (GHRH)] [9, 13–18]. Here, GNAS is linked to pseudohypoparathyroidism type 1A.