GNAS and pseudohypoparathyroidism type 1A: For example, maternally‐inherited inactivating coding‐region mutations of G‐protein subunit αs (Gαs), which is encoded by the GNAS gene, cause pseudohypoparathyroidism type 1a (PHP1a), which is characterized by PTH resistance together with Albright's hereditary osteodystrophy (AHO) 39; whereas, paternally‐inherited inactivating coding‐region GNAS mutations cause pseudopseudohypoparathyroidism (PPHP), which is characterized by AHO without PTH resistance (Table 1) 39.