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Vitamin B12-unresponsive methylmalonic acidemia type mut-

Synonym(s) Partial deficiency of methylmalonyl-CoA mutase
Vitamin B12-unresponsive methylmalonic aciduria type mut-
Prevalence Unknown
Inheritance Autosomal recessive
Age of onset Infancy
  • E71.1
MeSH -
MedDRA -


Disease definition

Vitamin B12-unresponsive methylmalonic acidemia type mut- is an inborn error of metabolism characterized by recurrent ketoacidotic comas or transient vomiting, dehydration, hypotonia and intellectual deficit, which does not respond to administration of vitamin B12.


Prevalence of this form of the disorder is not known. More than 450 cases have been reported to date.

Clinical description

The disease typically presents very early in life (


The disease is caused by partial deficiency in the activity of the mitochondrial vitamin B12-dependent enzyme methylmalonyl-CoA mutase which is a result of mutations in the MUT gene (6p21).

Genetic counseling

It is transmitted as an autosomal recessive trait.

Expert reviewer(s)

  • Dr David WATKINS

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