Pseudohypoparathyroidism [PHP]
= resistance to PTH due to dysfxal G Protein [due to imprinting defects in GNAS1: OMIM#139320], resulting in lo Ca, hi PO4, hi PTH (appropriate);
- T1a: phenotype of Albright hereditary osteodystrophy [AHO] [OMIM#103580]
- brachydactyly: short 4th,5th metacarpals, subcut calcifications, other skeletal anomalies
- short stature, obesity, round facies
- sometimes mental retardation
- usu. AD
- NB: do not confuse with: [McCune-]Albright syndrome: [OMIM#174800] activating GNAS1 mutation: polyostotic fibrous dysplasia: skeletal abnmlties, endocrine abnmlties: usu precocious puberty in females [occas males], also: hyperthyroidism, gigantism, Cushing's
- T1b: nml phenotype
- T2: nml phenotype, but differing urinary excretion of cAMP in response to exogenous PTH
- Pseudopseudohypoparathyroidism [PPHP]: T1a phenotype but nml biochem
|
|