Vitamin B12-Unresponsive Methylmalonic Acidemia Type Mut0

Vitamin B12-unresponsive methylmalonic acidemia type mut0 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.

Epidemiology

Prevalence of this disorder is not known.

Clinical description

The disease typically presents very early in life (<1 to 4 weeks), although rare later onset cases have been observed, with features including lethargy, failure to thrive, recurrent vomiting, dehydration, respiratory distress, muscle hypotonia, developmental delay, intellectual deficit, hepatomegaly and coma. Patients may show signs of anemia. They may also have potentially life-threatening ketoacidosis and/or hyperammonemia, renal and neurological complications, metabolic stroke and cardiomyopathy.

Etiology

The disease is caused by complete deficiency in the activity of the mitochondrial 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.