Our hosting provider will be performing UPS maintenance on Tuesday, Oct 25, 2016 between 8 AM and 5 PM PDT. SciCrunch searching services will be down during this time.

Preparing your results

Our searching services are busy right now. Your search will reload in five seconds.

Forgot Password

If you have forgotten your password you can enter your email here and get a temporary password sent to your email.

The natural history of the inherited methylmalonic acidemias.


Six biochemical and genetic forms of methylmalonic acidemia have been defined previously: two (mut degrees and mut-) resulting from defects in the mutase apoenzyme, and four (cbl A, cbl B, cbl C, and cbl D) resulting from deficient adenosylcobalamin synthesis. We retrospectively surveyed the clinical presentation, response to cobalamin supplementation, and long-term outcome in the four most prevalent mutant classes by collecting detailed information on 45 patients (15 mut degrees, 5 mut-, 14 cbl A, and 11 cbl B). Most patients presented acutely with a common set of clinical and laboratory findings; however, there were significant differences between mutant classes: mut degrees patients presented earlier in infancy than did cbl A and cbl B patients; in response to cobalamin supplements, marked decreases in the concentration of methylmalonic acid in blood or urine were reported in most cbl A patients and in nearly half the cbl B patients, but not in mut degrees or mut- patients; and finally, most cbl A, cbl B, and mut- patients were still living, whereas most mut degrees patients died during the first few months of life. Our data indicate that genotypic classification of the methylmalonic acidemias has prognostic and therapeutic use as well as diagnostic value.

Pubmed ID: 6132336


  • Matsui SM
  • Mahoney MJ
  • Rosenberg LE


The New England journal of medicine

Publication Data

April 14, 1983

Associated Grants

  • Agency: NIADDK NIH HHS, Id: AM-12579

Mesh Terms

  • Amino Acid Metabolism, Inborn Errors
  • Cobamides
  • Humans
  • Infant
  • Infant, Newborn
  • Malonates
  • Methylmalonic Acid
  • Methylmalonyl-CoA Mutase
  • Mutation
  • Prognosis
  • Retrospective Studies
  • Vitamin B 12