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At a glance

Very rare rhizomelic dwarfism disorder characterized by short humeri, hypoplastic everted humeral condyle, proximal radioulnar diastasis, anterolateral radial head dislocation, depressed nasal bridge, broad base of nose, and long philtrum.

Synonyms

Autosomal recessive Omodysplasia Syndrome; generalized Omodysplasia Syndrome; Omodysplasia Syndrome.

History

First described in three cases by P. Maroteaux in 1989. Etymologically omodysplasia is defined as shoulder (omo—Greek for shoulder) dysplasia.

Incidence

Fewer than 50 cases described. Many patients are of Hungarian Gypsy origin.

Genetic inheritance

Autosomal dominant form due to mutation of FZD2 gene on 17q21.31. Autosomal recessive form due to mutation of glypican 6 (GPC6) gene on chromosome 13q.31.

Pathophysiology

Pathologic characteristics of this medical condition are the presence of omodysplastic diaphyseal plates showing an expanded zone of proliferating cartilage and an increased number of closely packed small chondrocytes. A functional deficiency of diaphyseal cells is partially replaced by a large number of small chondrocytes in the proliferating zone of the diaphyseal plate. However, the replacement is considered inefficient and leads to weakness of the bone structure. Possible male predominance.

Diagnosis

Clinical appearance and bone radiographs show short humeri, radioulnar diastasis at the elbows, short radii and ulnae, short femora with club-shaped upper end. In some cases, a long bone may be missing.

Clinical aspects

  • Autosomal Dominant Form: Short humeri, dislocated radial head, short first metacarpals, brachycephaly, facial dysmorphism with round face, frontal bossing, short nose, long philtrum, small mandible, large, low-set ears, and short neck. Variable degrees of genitourinary anomalies.

  • Autosomal Recessive Form: Micromelia, severe short stature and developmental delays. Congenital heart disease (patent ductus arteriosus, atrial septal defect, coarctation of aorta, mitral valve prolapse) may be associated. Midline hemangiomas are often present in infants.

Precautions before anesthesia

Check for congenital heart disease (echocardiography), atlantoaxial joint instability, and presence of sleep apnea syndrome (night oximetry) as for any form of dwarfism. Stenosis of the spinal canal can produce paraparesis, and scoliosis with pectus carinatum can cause restrictive lung disease.

Anesthetic considerations

Direct laryngoscopy and tracheal intubation can be difficult because of the presence of macroglossia, micrognathia, and short neck; a laryngeal mask airway and equipment for difficult intubation should be ready for use. In case of sleep apnea syndrome close observation required after general anesthesia. In case of C1-C2 subluxation, the neck should be stabilized during intubation and positioning of the patient. Special attention to the cervical spine during positioning. Confirm the absence of spinal cord compression before induction of anesthesia or consider somatosensory evoked potentials intraoperatively.

Pharmacological implications

No specific implications.

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