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
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
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.