GNAS and progressive osseous heteroplasia: As a key regulator in skeletal development, GαS inhibits hedgehog (Hh) signaling and loss of GNAS results in aberrant Hh signaling activation.211 As previously discussed, inactivating mutations within the GNAS gene results in either Albright's hereditary osteodystrophy (AHO) or POH (progressive osseous heteroplasia).