[MIM 252 150, 252 160, 272 300, 615 501]

Rare. Encephalitis of metabolic origin. Autosomal recessive transmission.

Two genetic causes:

-        mutation of one of the genes involved in the biosynthesis of the molybdenum sulfurase (see MOCOD) causing a deficiency in xanthine dehydrogenase, xanthine aldehyde oxidase, the reducing component of mitochondrial amidoxime and sulfite oxidase

-        mutation of the SUOX gene coding for sulfide oxidase (oxidation of the sulfide group, step of sulfur amino acids catabolism)

Clinical presentation:

-         severe disorders of muscle tone (axial hypotonia and spastic quadriparesis), convulsions resistant to treatment, autonomal dysfunction; later, cerebral atrophy  and secondary microcephaly. Often death in childhood.

-         moderate: dystonia,  marfanoid aspect with dislocation of the lens (childhood), brain malformation

-        frequent dysmorphism: prominent forehead, sunken eyes, small nose, thick lips with a long philtrum, narrow bifrontal diameter.

Rapid diagnosis: urinary test strip to detect high sulphite levels.

If type A MOCOD is detected very early (neonatal period), daily IV administration of cyclic monophosphate pyranopterine (Precursor-Z)  permits an almost normal neurological and behavioral development.

Anesthetic implications: 

according to the neurological sequelae. Epilepsy; since S-sulphocysteine accumulates in case of deficiency in sulphite oxidase and has  excitatory neuronal action similar to glutamate, it is possible that the use of NMDA antagonists such as ketamine could be useful in these patients.

References : 

-        Bayram E, Topcu Y, Karakaya P et al. 
Molybdenum cofactor deficiency: review of 12 cases. 
Eur J Pediatr Neurol 2013; 17:1-6.

-         Schwahn BC, Van Spronsen FJ, Belaidi AA, Christodoulou J, Derks TG et al. 
Efficacy and safety of cyclic pyranopterin mononphosphate substitution in severe molybdenum cofactor deficiency type A: a prospective cohort study. 
The Lancet 2015; 386: 1955-63.

Updated: September 2019