McCune–Albright syndrome: description of three clinical cases, features of diagnostics and treatment

Abstract

McCune Albright syndrome (MAS) is a rare disorder caused by a sporadic postzygotic mutation in the GNAS gene, which encodes the alpha subunit of the Gs signaling protein.Permanent activation of the Gs protein leads to uncontrolled production of intracellular cAMP, and autonomic hyperfunction of target organs. Estimated prevalence of the disease – 1\100000 to 1\1000000. For the first time, MAS syndrome was described in 1936 as a triad of symptoms – fibrous dysplasia of bones (FD), spots on the skin of the color of «coffee with milk» and premature sexual development. However, it is now known, that the phenotype of the disease is much more complex. This is primarily due to the mosaic type of mutation in the GNAS gene, which determines a wide range of clinical manifestations, and presents certain difficulties in the diagnosis of this syndrome. Various endocrinopathies can be manifestations of MAS like an acromegaly, a hyperthyroidism, Cushing’s syndrome, hypophospatemic osteomalacia as well as damage to other organs and systems, namely the pathology of the gastrointestinal tract, hepato-biliary cardiovascular systems. This article presents three late diagnosed clinical cases of MAS in patients with coffee-milk spots and FD, multinodular goiter; in two cases in combination with acromegaly. We have demonstrated the possibilities of drug therapy for acromegaly in MAS, as well as the experience of using bisphosphonate for the treatment of FD.The knowledge of clinical manifestations of the MAS, early diagnostics and possibilities of drug therapy in the management of these patients have the important prognostic value for improving the quality of patient’s life.