Pseudohypoparathyroidism Type 1A

Pseudohypoparathyroidism Type 1A (PHP1A) is a rare genetic disorder that affects the body's ability to respond to the hormone parathyroid hormone (PTH), which regulates calcium and phosphate levels. This condition primarily impacts the endocrine system, leading to low calcium and high phosphate levels in the blood despite normal or elevated PTH levels. People with PHP1A often have distinctive physical features such as short stature, round face, and shortened fingers. The disorder can also cause symptoms related to low calcium, including muscle cramps, seizures, and tingling sensations. PHP1A results from mutations in the GNAS gene, which affects hormone signaling pathways. Overall, it disrupts normal bone and mineral metabolism, causing significant health challenges.

Pseudohypoparathyroidism Type 1A (PHP1A) is a genetic disorder characterized by end-organ resistance to parathyroid hormone (PTH) due to mutations in the GNAS gene encoding the alpha subunit of the stimulatory G protein (Gsα). This leads to impaired activation of adenylate cyclase and reduced cyclic AMP production in target tissues, primarily the renal proximal tubules, causing hypocalcemia and hyperphosphatemia despite elevated circulating PTH levels. PHP1A is also associated with Albright hereditary osteodystrophy (AHO) phenotype, which includes short stature, brachydactyly, subcutaneous ossifications, and round facies. The disorder may involve resistance to other hormones that signal via Gsα, such as thyroid-stimulating hormone (TSH), leading to hypothyroidism. The condition is inherited in an autosomal dominant pattern with maternal imprinting effects influencing phenotype expression. PHP1A is clinically significant due to its complex endocrine abnormalities and characteristic physical features.