Definition:

Sulfite oxidase deficiency is a rare inherited disease with severe neurological symptoms such as intractable neonatal or infantile seizures, hypotonia or hypertonia, feeding difficulties, profound developmental delay, and dislocated lens. Isolated sulfite oxidase deficiency results from defects in the enzyme sulfite oxidase, which is responsible for the oxidation of sulfite to sulfate. Several mutations have been identified from patients suffering from isolated sulfite oxidase deficiency. The more common molybdenum cofactor deficiency [DS:H00192] leads to combined defects in xanthine dehydrogenase and sulfite oxidase, as sulfite oxidase is 1 of 3 enzymes in humans that requires molybdenum as a cofactor, the other 2 being xanthine oxidase and aldehyde oxidase. The seizures in isolated sulfite oxidase deficiency may even begin prenatally, and are much more severe compared with those in molybdenum cofactor deficiency.