They comprise extremely rare forms of congenital pseudohypoparathyroidism caused by tissue resistance to PTH, collectively named “inactivating PTH/PTHrP signaling disorder” (iPPSD), all of which manifest skeletal alterations, ranging from hyperostosis, osteosclerosis, osteodystrophy, and heterotopic ossifications of soft tissues [42]. This evidence concerns the gene PTH and pseudohypoparathyroidism type 1A.