Pseudohypoparathyroidism is a term applied to a heterogeneous group of disorders whose common feature is end-organ resistance to parathyroid hormone (PTH). In addition to PTH resistance, PHP IA is characterized by resistance to other hormones, including thyroid-stimulating hormone and gonadotropins. PHP IA is associated with a constellation of clinical features referred to as Albright hereditary osteodystrophy (AHO), which includes short stature, obesity, round facies, subcutaneous ossifications, brachydactyly, and other skeletal anomalies. Some patients have mental retardation. In contrast, pseudopseudohypoparathyroidism (PPHP) is characterized by the physical findings of AHO but without hormone resistance. PHP1A occurs only after maternal inheritance of the molecular defect, whereas PPHP occurs only after paternal inheritance of the molecular defect. This is an example of imprinting, with differential gene expression depending on the parent of origin of the allele. [From OMIM]