Jansen disease is a skeletal abnormality in which the epiphyses are normal, but the metaphyseal tissues are replaced by masses of cartilage, producing interference with endochondral bone formation, expansion and thinning of the metaphyseal cortices. It is also known as Jansen metaphyseal dystotosis. Murk Jansen Type Metaphyseal chondordysplasia, JMC

 

Jansen disease is rare progressive disorder in which the potions of bones of the arms and legs develop abnormally with unusual cartilage formations and subsequent abnormal bone formation at the end portions of long bones. This occurs due to genetic mutation.

It is an autosomal dominant human disorder featured by short lined dwarfism due to delayed chondorcyte differentiation and is associated with severe hypercalcemia and hypophosphatemia with normal or undetectable serum levels of para thyroid hormone.

Signs and symptoms

• Short arms
• Short legs
• Short stature
• Stiffening of joints
• Swelling of joints
• Micrognathia
• Prominent eyes
• High skull vault
• Bell shaped thorax
• Hypertelorism
• Widening of costochondral junctions
• Prominent cheeks
• High arched palate
• Wide cranial sutures
• Waddling gait
• Squatting stance
• Facial abnormalities
• Skeletal malformation
• Abnormal hardening of sclerotic bones in the back of neck
• Blindness
• Deafness

Diagnosis:

• Radiological studies of bones
• Serum calcium and phosphorous level
• Increased calcium level (hypercalcemia)
• Raised serum alkaline phosphatase activity
• Increased osteocalcin concentrations
• Iliac crest biopsy 

Treatment:

There is no specific treatment for this disorder.