Heterogeneous genetic alterations, including:–Frequent germline ARMC5 mutationsa (~55%) in adult-onset PBMAH–Postzygotic somatic mosaicism of GNASa in childhood-onset PBMAH associated with MAS–Other molecular defects involving cAMP/PKA signaling pathway (GNAS, GPCRs, MC2R, PDE11A, PDE8B, PRKACA, PRKAR1A); and MEN1, APC, FH. The gene discussed is PRKAR1A; the disease is McCune-Albright syndrome.