SC Phocomelia Syndrome

At a glance

A very rare, autosomal recessive, severe, polymalformative disease characterized by cranial and maxillofacial deformities, limb anomalies, and intellectual disability.

Synonyms

Hypomelia-Hypotrichosis-Facial Hemangioma Syndrome; SC-Pseudothalidomide Syndrome; SC Syndrome; Roberts Syndrome; Appelt-Gerken-Lenz Syndrome; Tetraphocomelia-Cleft Palate Syndrome.

History

Initially described by plastic surgeon John Bingham Roberts in Philadelphia in 1919. It has been proposed that the three medical conditions: SC Phocomelia Syndrome, ☞TAR Syndrome, and ☞Roberts Syndrome are not separate.

Incidence

Unknown, fewer than 200 individuals affected.

Genetic inheritance

Autosomal recessive inheritance.

Pathophysiology

Mutations in cohesion 1 homologue 2 (ESCO2) gene on chromosome 8p21.1. Chromosome studies reported premature centromere separation, splaying the Y-chromosome heterochromatin and repulsing the short arms of the acrocentric chromosomes.

Diagnosis

Association of nearly symmetrical reductive malformations of the limbs (resembling phocomelia), flexion contractures of various joints, multiple minor anomalies, intrauterine and extrauterine growth retardation, and mental retardation.

Clinical aspects

This severe polymalformative syndrome involves skeletal signs that can affect the whole body. Micrognathia and microbrachycephalic skull with wormian bones in the occipital region may occur. Hand abnormalities can include absence of the thumb, shortening of the first metacarpal bone, hypoplasia of the first digit, fusion of the fourth and fifth metacarpals, clinodactyly of the second and fifth digits, and hypoplasia of the middle phalanges, with symmetric reduction deformity (upper limbs being more severely affected than the lower ones) and flexion contractures of the joints. Midfacial defects include cleft lip with or without cleft palate and prominent premaxilla, hypertelorism, midfacial capillary hemangioma, thin nares, shallow orbits, and prominent eyes. Other clinical features concern hypotrichosis with scanty silvery blond hair, growth and occasional mental retardation, seizures, aortic stenosis, and cloudy cornea. Often lethal in neonatal period.

Precautions before anesthesia

Evaluate cardiac function (clinical, chest radiograph, echocardiography), neurological function (maintenance of seizure therapy), and airway (clinical, radiography).

Anesthetic considerations

Arterial and venous access because blood pressure can be difficult to manage as a consequence of the limb deformities. Direct laryngoscopy and tracheal intubation can be difficult because of micrognathia and skull deformation. In these conditions, it is highly recommended to maintain spontaneous respiration until trachea is intubated and lung ventilation is confirmed.

Pharmacological implications

Use endocarditis prophylaxis as indicated. Antiepileptic treatment should be continued on day of surgery; consider interaction between epileptic and anesthetic drugs.

Other conditions to be considered

• ☞Holt-Oram Syndrome: Characterized by thumb anomaly and atrial septal defect, although abnormality of the upper extremities can be ...