Jansen type metaphyseal chondrodysplasia, also known as Jansen disease, is a rare condition in which the bones of the arms and legs develop abnormally due to abnormal cartilage and bone formation at the large end of the bones (metaphyseal chondrodysplasia). This causes short arms and legs, and short stature (a form of dwarfism). Other symptoms are variable in affected individuals but may include: deformed bones in the hands and feet, facial and skeletal malformations, stiffening/swelling of joints, hardened bones in the back of the head, high levels of calcium in the blood (hypercalcemia), and blindness and/or deafness (due to bone deformities in the skull). Jansens disease is autosomal dominant, meaning that it is passed from parent to child, and if one parent has it there is a 50% chance that each of their children will have it as well. This condition is typically diagnosed in infancy or childhood through a physical examination. Treatment varies and depends on the severity of the case.