Pseudohypoparathyroidism

Pseudohypoparathyroidism is characterized by elevated plasma levels of PTH and symptoms consistent with reduced PTH levels - hence a resistance of peripheral organs to PTH.

Classification

Type 1 is further branched into types 1a, 1b, 1c. Type 1a is equivalent to Albright hereditary osteodystrophy, type 1b has not skeletal abnormalities, and in type 1c the protein shows normal activity in erythrocytes.

Differentials

Type 1 is cause by mutation or impaired imprinting of GNAS1 gene. In contrast to type 2 the renal cAMP excretion in response to PTH administration is blunted. Type 2 is not yet characterized genetically.

The genetic background of type 2 pseudohypoparathyroidism is not yet characterized. Moreover, severe vitamin D deficiency resembles pseudohypoparathyroidism with normal renal cAMP response to PTH, so an acquired disease or a hereditary disease in vitamin D metabolism have to be ruled out prior to searching a gene responsible for pseudohypoparathyroidism type 2.[Error: Macro 'ref' doesn't exist]

Systematic

Metabolic bone disease
	Hereditary Rickets
	Inherited human diseases of heterotopic bone formation
	Osteopetrosis
	Osteoporosis/renal Osteodystrophy
	Pseudohypoparathyroidism
		Albright hereditary osteodystrophy
			GNAS
		Pseudohypoparathyroidism type IB
			GNAS
			STX16