MOCOD

Acronym for MOBlybdenum COfactor Deficiency.

(MoCD)

Rare: prevalence estimated at 1/200,000 births. Autosomal recessive transmission. Deficiency in xanthine dehydrogenase, xanthine aldehyde oxidase, components reducing mitochondrial amidoxime and in sulfite oxidase due to a mutation of one of the genes involved in the biosynthesis of molybdenum sulfurase.

Several types:

- type A: mutation of the MOCS1 gene on 6p21.2: lack of synthesis of cyclic monophosphate pyranopterine

- type B: mutation of the MOCS2 gene on 5q11: accumulation, by non-use, of pyranopterine monophosphate

- type C: mutation of the HLPG gene on 16q24 :

Clinical signs:

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

- moderate form: dystonia, marfanoid aspect with dislocation of the lens, brain malformation

Rapid diagnosis: urine test strip to detect high levels of sulphites

In case of very precocious diagnosis (neonatal period) of type A MOCOD, daily IV administration of pyranopterine cyclic monophosphate (Precursor-Z) leads almost normal growth and neurological development.

Anesthetic implications:

on the basis of neurological sequelae. Epilepsy; since S-sulphocysteine, a metabolite that accumulates in case of sulphite oxidase deficiency,could have an excitatory effect at the neuronal level 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. T
The Lancet 2015; 386: 1955-63.

Update: December 2018