Also known as Albright hereditary osteodystrophy.

Unresponsiveness of kidney to PTH → hypocalcemia despite ↑ PTH levels- Due to defective G_S protein α-subunit causing end-organ resistance to PTH- Autosomal dominant- Defect must be inherited from mother due to imprinting

↓ Ca²⁺ despite ↑ PTH levels

Presentation:- Shortened 4th/5th digits- Short stature- Obesity- Developmental delay