Pseudohypoparathyroidism type 2

The following summary is from Orphanet, a European reference portal for information on rare diseases and orphan drugs.

Orpha Number: 94090

Definition

Pseudohypoparathyroidism type 2 (PHP2) is a type of pseudohypoparathyroidism (PHP; see this term) characterized by resistance to parathyroid hormone (PTH), which manifests with hypocalcemia, hyperphosphatemia and elevated PTH levels, absence of Albright's hereditary osteodystrophy (AHO; see this term), and normal expression of the Gs protein with a normal urinary cAMP response.

Epidemiology

The prevalence is unknown.

Clinical description

The clinical manifestations of PHP-2 have been poorly characterized but are similar to those seen in pseudohypoparathyroidism type1b (PHP-1b; see this term). Patients present with symptoms related to low levels of calcium including: seizures, tetany (including muscle twitches and hand and foot spasms), numbness cataracts, and dental problems. Unlike PHP-1b, those with PHP-2 demonstrate a normal urinary cAMP response.

Etiology

To date, no specific genetic alteration responsible for this disorder has been detected. It has been hypothesized that in most cases it may be an acquired defect secondary to vitamin D deficiency such as in misdiagnosed secondary renal hyperparathyroidism.

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