In most cases, the diagnosis of Jansen type metaphyseal chondrodysplasia may be suspected during infancy or early childhood. The diagnosis may be confirmed by a thorough clinical evaluation, identification of characteristic physical findings, and a variety of specialized tests, particularly advanced imaging techniques.
During childhood, affected individuals may begin to exhibit progressive stiffening and swelling of many joints and/or an unusual "waddling gait" and squatting stance. In addition, affected individuals have abnormally high levels of calcium in the blood (hypercalcemia). The range and severity of symptoms may vary from case to case. Most cases of Jansen type metaphyseal chondrodysplasia occur randomly as the result of a spontaneous genetic change (i.e., new genetic mutation).
Suggestions for establishing a diagnosis:
1) Laboratory measurements: Serum/plasma: Ca, P, PTH, 1,25(OH)2 vitamin D, 25-vitamin D, alkaline phosphatase, and Chem 10 (which includes Na, K, Cl, CO2, BUN, creatinine). Urine: calcium and creatinine.
2) X-ray results (hands, knees, skull), renal ultrasound
3) Family history
4) EDTA blood (purple top) for DNA extraction and molecular analysis
If more information, contact Dr. Harald Jueppner, Boston Mass. General Hospital.