Jansen disease is?

Ans. is 'a' i.e.. Defect of PTH receptor o Jansen syndrome occurs due to activating mutations in the PTH/PTHrP receptor (PTHIR).o Rare autosomal dominant syndrome.o The disorder leads to short-limbed dwarfism due to abnormal regulation of chondrocyte maturation in the growth plates of the bone that are formed through an endochondral process.o In adult life, there are numerous abnormalities in bone, includingy Multiple cystic resorptive areas resembling those seen in severe hyperparathyroidismy Hypercalcemia and hypophosphatemiay Undetectable or low PTH levels are typically seen.