GNAS and pseudohypoparathyroidism: The term Pseudohypoparathyroidism (PHP) identifies a heterogeneous group of hereditary disorders caused by (epi) genetic [1] alterations affecting the GNAS locus, on chromosome 20q13 [2, 3] Within this locus, the homonymous gene encodes for Gsα protein, which is involved in the intracellular signal transduction of multiple peptide hormone signals and whose altered function explains the complex clinical manifestations affecting PHP patients [4].