Pseudohypoparathyroidism

The pseudohypoparathyroidism (PHP) spectrum of disorders encompasses a variety of features that include hormone resistance, short stature, brachydactyly, heterotopic ossifications, obesity, metabolic disturbances, craniofacial and dental abnormalities, defects in skeletal homeostasis, and cognitive impairments. An understanding of the etiologies and presentations of these abnormalities is critical to understanding the specific disorders themselves, the majority of which result from either genetic or epigenetic defects that affect GNAS, the gene encoding the alpha subunit (Gαs) of the heterotrimeric G protein that couples heptahelical receptors to stimulation of adenylyl cyclase. The goal of this chapter is to provide relevant information regarding PHP and related disorders with respect to the clinical features and underlying etiologies of these disorders, as well as guidelines for the diagnosis and management of these conditions.