Does pseudohypoparathyroidism Type 1B typically present with Albright hereditary osteodystrophy (AHO) phenotype?

• A. No
• B. Yes
• C. Only in some cases
• D. Not related to AHO

Answer: (A)

The main idea here is how Albright hereditary osteodystrophy (AHO) relates to different forms of pseudohypoparathyroidism. AHO features—such as short stature, brachydactyly, obesity, and subcutaneous calcifications—reflect dysfunction of the GNAS pathway in multiple tissues and are typical of pseudohypoparathyroidism type 1A, which involves coding mutations in GNAS that cause both hormone resistance and AHO.

Pseudohypoparathyroidism type 1B, on the other hand, is driven mainly by imprinting defects at the GNAS locus that lead to resistance to parathyroid hormone (PTH) without widespread tissue resistance. This means the characteristic AHO skeletal phenotype is not typically present in PHP1B. In rare cases with broader methylation defects, there might be milder or atypical features, but the classic presentation of PHP1B does not include AHO.