Jansen's metaphyseal chondrodysplasia (JMC) is a very rare autosomal dominant skeletal dysplasia characterized by short-limbed short stature (due to severe metaphyseal changes that are often discovered in childhood by imaging), waddling gait, bowed legs, contracture deformities of the joints, short hands with clubbed fingers, clinodactyly, prominent upper face and small mandible, as well as chronic parathyroid hormone-independent hypercalcemia, hypercalciuria, and mild hypophosphatemia.
Here we share radiographic images to help with diagnosis of Jansen’s disease:
Jansen’s patients show extreme disorganization of the metaphyses of the long bones and of the metacarpal and metatarsal bones is in sharp contrast to the almost normal appearance of the epiphyseal centers, which on x-ray appear widely separated from the long bones. The chin is receding. The fingers, especially the distal phalanges, are very short. The spine, pelvis, and lower legs are distorted.
Jansen’s patients present at birth with prominent eyes, choanal stenosis, wide cranial sutures, highly arched palate, micrognathia, rib fractures, and irregularities of the metaphyses of the long bones resembling rickets. At the age of 2-3, patients show stunted growth, waddling gait, enlarged joints, prominent supraorbital ridges, and frontonasal hyperplasia.
A full list of Signs and Symptoms are as follows:
Autosomal dominant inheritance
Bowing of the long bones
Clinodactyly of the 5th finger
Clubbing of fingers
Elevated alkaline phosphatase
Knee flexion contracture
Misalignment of teeth
Prominent supraorbital arches in adult
Severe short stature
Short long bone
Thick skull base