Extremely rare progressive disorder in which portions
of the bones of the arms and legs develop abnormally with unusual cartilage
formations and subsequent abnormal bulbous metaphyses (metaphyseal
chondrodysplasia). Affected individuals exhibit unusually short arms and
legs and short stature (short-limbed dwarfism), findings that typically
become apparent during early childhood. Infants with Jansen-type metaphyseal
chondrodysplasia may have characteristic facial abnormalities and additional
skeletal malformations. Hypercalcemia is present.
Jansen Metaphyseal Dysplasia; Murk Jansen Metaphyseal
Chondrodysplasia; Chondrodysplasia Jansen type
Fewer than 25 cases have been reported in the
Autosomal dominant. Majority of cases are
Caused by mutation in parathyroid hormone receptor
1 gene (PTHR1), which has been mapped to 3p22-p21.1.
Clinically evocated by the postnatal onset of severe
short stature with joint dysfunction. Radiologic signs vary with age,
showing diffuse radiolucency at birth, irregular calcification in childhood,
and bulbous deformations of long bone extremities.
Severe short stature (adult height: 125 cm [49.2
inches]) and enlarged joints with flexion contractures (knees, hips). Small
thorax, kyphoscoliosis. Irregular and disorganized metaphyses but normal
epiphyses. Small face with prominent supraorbital ridges; micrognathia;
sometimes choanal atresia, high-arched palate, mandibular cyst. Wide cranial
sutures with hyperostosis of calvaria and cranial bone sclerosis. Variable
deafness. Waddling gait. Biochemistry: Hypercalcemia, hypercalciuria, hypophosphatemia.
Increased urinary cAMP; elevated 1,25(OH2D3
, alkaline phosphatase;
low/absent parathyroid hormone.
Assess renal function and serum
calcium and phosphate levels. Hypercalcemia may be asymptomatic or may be
associated with polyuria, dehydration, thrombosis, muscle weakness, and
hyporeflexia. ECG is recommended. In the presence of symptomatic or
clinically significant hypercalcemia, active steps should be taken to lower
the serum levels (i.e., with saline rehydration/diuresis). Phosphate
supplementation may be required. Evaluate carefully the airway for potential difficult tracheal intubation (clinical,
radiograph). Evaluate severity of the disease (clinical, full history,
Anesthesia in this condition has not
been described. The features of the disease suggest that face-mask
ventilation, direct laryngoscopy, and tracheal intubation may be difficult.
If it is the case, spontaneous respiration should be maintained until
confirmation that face-mask ventilation can support gas-exchange or until
the trachea has been secured and lung ventilation confirmed.
Renal dysfunction may be present. Patient positioning may be difficult
because of contractures. Patients may be prone to fractures. Hypercalcemia
may lead to arrhythmias and hypertension. Hyperventilation may be useful in
life-threatening hypercalcemia. Neuromuscular monitoring is recommended to
facilitate titration of muscle relaxants.
Metabolism/excretion of some drugs
may be altered in the presence of renal dysfunction. Digitalis toxicity is
exacerbated by hypercalcemia. The response to neuromuscular blockers may be
potentialized by hypercalcemia. Consider renal function before using
Aguilera IM, Vaughan RS: Calcium and the anaesthetist. Anaesthesia
Schipani E, Langman C, Hunzelman J, et al: A novel parathyroid hormone
(PTH)/PTH-related peptide receptor mutation in Jansen's metaphyseal