Metaphyseal Chondrodysplasia, Schmid Type

At a glance

It is a very rare inherited disorder characterized by short stature with abnormally short arms and legs (short-limbed dwarfism). Other physical characteristics may include outward “flaring” of the lower rib cage, genu varum, pain in the legs, and/or hip deformities (coxa vara). Such abnormalities of the legs and hips typically result in an unusual “waddling” gait.

Synonyms

Metaphyseal Dysplasia, Schmid Type; Schmid Metaphyseal Dysplasia; Japanese Type Metaphyseal Dysplasia; Metaphyseal Dysplasia Japanese Type.

History

It was first described in 1949 by F. Schmid, a German researcher.

Nature

Congenital anomaly of collagen located in the metaphyses.

Incidence

The exact incidence remains unknown. It affects males and females in equal numbers.

Genetic inheritance

Autosomal dominant with variable expression; de novo mutations not rare.

Pathophysiology

Mutation in COL10A1 gene for collagen type X, alpha 1, the expression of which is restricted to the hypertrophic zone of the growth plate. This explains the metaphyseal location of the disease and the mechanical weakness of the growth plates in these patients.

Diagnosis

Clinical picture, but rickets and causes of hypophosphatasemia should be excluded.

Clinical aspects

Moderate short stature, bowed legs, coxa vara, waddling gait are associated with this disorder. Irregular metaphyses, but the radiological picture can temporarily disappear after prolonged bed rest. Enlarged femoral capital epiphyses. No vertebral anomalies. Adult height: approximately 130 to 160 cm (51.2-63 inches).

Anesthetic considerations

Because of the numerous skeletal anomalies, positioning of the patient must require special attention.

References