Pseudohypoparathyroidism

Pseudohypoparathyroidism is a rare autosomal dominant genetic condition in which the body's tissues resist the action of parathyroid hormone even though the hormone itself is present at normal or elevated levels, affecting roughly 0.3 to 1.1 people per 100,000 worldwide. The underlying defect lies in dysfunctional G proteins, particularly the Gs alpha subunit, which prevents cells from responding properly to parathyroid hormone signaling. As a result, patients develop low blood calcium alongside elevated phosphate levels and inappropriately high circulating parathyroid hormone, which can cause muscular spasms, cramping and, in severe cases, seizures from calcium deficiency. Type 1a of the condition carries distinctive skeletal features, including shortened fourth and fifth finger bones and a rounded facial appearance, while other subtypes of the disorder can present the same hormonal abnormalities without these physical markers.