Jansen’s metaphyseal chondrodysplasia (JMC) is an ultra-rare disease of skeletal development and mineral ion balance. JMC is caused by mutations in the parathyroid hormone (PTH) receptor, which is present at particularly high levels in growth plates, bones and kidneys. The mutant PTH receptors of JMC are overactive, resulting in bone deformities, extremely short stature and chronic kidney disease, which often requires treatment by dialysis or kidney transplantation later in life. Other complications include premature closure of the spaces between the bones of the skull, leading to damage of cranial nerves and potential vision and hearing loss. Currently, there is no effective treatment for JMC. The lead collaborators have identified a peptide (termed PTH-IA) that can reduce the high baseline activity of the mutant PTH receptors. The goal of this project is to complete the preclinical studies necessary to enable clinical trials of the PTH-IA for JMC.