Sulfocysteinuria

At a glance

An inborn error of metabolism leading to fatal neurologic disease, severe development delay, and ectopia lentis in children. Infants often present with acute hemiplegia. Clinically manifested by ataxic gait, generalized dystonia, and choreoathetosis. Confirmed by the presence of sulfite in the urine (“strip-test”).

Synonym

Sulfite Oxidase Deficiency.

Incidence

Fewer than 50 patients reported.

Genetic inheritance

Autosomal recessive.

Pathophysiology

Mutation in the sulfite oxidase gene located on 12q12.2 resulting in defect in sulfite oxidase, the enzyme converting sulfite to sulfate leading to accumulation of sulfite and decreased secretion of inorganic sulfate. The excess sulfite is partially converted to thiosulfate and to S-sulfocysteine, and also combined with the aldehyde groups. This may lead to poor crosslinking of collagen and elastin.

Diagnosis

Clinical and biochemical features. Blood sulfite level is low. Urine collection shows increased sulfite and decreased sulfate excretion. Cultured fibroblast enzyme study shows decreased sulfite oxidase activity.

Clinical aspects

Patient usually presents in early infancy with infantile acute hemiplegia, hypotonia, hypertonia, generalized dystonia, therapy resistant seizures, progressive choreoathetoid movement, ataxia, myoclonus, and progressive cerebral palsy. The finding of dislocated lens on ophthalmological examination is highly suspicious. Course of disease usually follows a rapid deterioration and is often fatal in early childhood, although a milder course has also been described. No long-term treatment available, distinguish from other treatable diseases, such as ☞Molybdenum cofactor deficiency, Type A (MoCD Syndrome).

Precautions before anesthesia

Assess neurological function from medical history and physical examination. The respiratory status should be assessed because there is a potential risk of aspiration and pneumonia. General history, examination, chest radiograph, and arterial blood gas analysis should be obtained.

Anesthetic considerations

No reported case. Patient may not be cooperative because of the mental retardation. Potential risk of aspiration pneumonia in severe cases.

Pharmacological implications

There are no known implications.

References