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Extremely rare, congenital, severe neurologic anomalies including seizures, spastic tetraparesis, brain atrophy, mental retardation, abnormal muscle tone and myoclonic spasms, dislocated lenses, and xanthine urinary stones.

MOCOD; Sulfite oxidase deficiency.

Extremely rare; approximately 50 patients described.

Autosomal recessive; heterozygotes show no symptoms.

This cofactor is essential for function of the enzymes sulfite oxidase, xanthine dehydrogenase, and aldehyde oxidase. Symptoms are the result of combined deficiencies of these enzymes. However, isolated deficiency in sulfite oxidase produces the same symptoms. Accumulation of toxic metabolites produces severe encephalopathy, demyelinization of white matter, gliosis, and diffuse spongiosis of the brain.

Deficiency of sulfite oxidase in fibroblasts or of molybdenum cofactor in liver biopsy. High concentrations of sulfite, thiosulfate, taurine, xanthine, and hypoxanthine, but very low levels of uric acid in the urine. Antenatal diagnosis is possible.

Clinical manifestations are apparent within a few weeks of birth and were formerly called “infantile encephalopathy”: mainly severe convulsions unresponsive to therapy and caused by sulfite production from oral protein intake. Poor feeding and vomiting, seizures, spastic quadriparesis, and severe developmental delay. Dilated ventricles, unresponsiveness to light. Bilateral dislocation of the ocular lens is a common finding. There is no effective treatment, and death usually occurs before age 2 years.

Assess neurologic status until the day of surgery; optimize seizure therapeutic management.

Anesthetic management in this condition has not been described. The severity of neurologic defects determines anesthetic management. Patients may be at risk for pulmonary aspiration and recurrent infections. Poor feeding and vomiting may lead to electrolyte abnormalities, which should be corrected preoperatively.

Succinylcholine should be avoided in presence of spastic tetraparesis. Seizure medications must be optimized intraoperatively and postoperatively.

Rezvani I: Defects in metabolism of amino acids, in Behrman RE, Kliegman RM, Arvin AM (eds): Nelson Textbook of Pediatrics. 16th ed. Philadelphia, WB Saunders, 1995, p 344.

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