A syndrome of methylmalonic aciduria, homocystinuria, megaloblastic anemia and neurologic abnormalities in a vitamin B12-deficient breast-fed infant of a strict vegetarian

N Engl J Med. 1978 Aug 17;299(7):317-23. doi: 10.1056/NEJM197808172990701.


We studied a six-month-old infant with severe megaloblastic anemia, coma and hyperpigmentation of the extremities. He was found to have methylmalonic aciduria (79 mumol per milligram of creatinine) and homocystinuria (0.85 mumol per milligram of creatinine). Additional biochemical abnormalities included cystathioninuria, glycinuria, methylcitric aciduria, 3-hydroxypropionic aciduria and formic aciduria. The concentration of vitamin B12 in the serum was 20 pg per milliliter. This severe nutritional deficiency was a consequence of inadequate intake, for the infant was exclusively breast-fed by a strictly vegetarian mother who manifested methylmalonic aciduria. Our observations emphasize the importance of educating strict vegetarians about the deficiency of vitamin B12 in their diets and the importance of vitamin B12 supplementation.

Publication types

  • Case Reports
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adult
  • Amino Acid Metabolism, Inborn Errors / diagnosis
  • Anemia, Megaloblastic / etiology
  • Breast Feeding*
  • Diagnosis, Differential
  • Diet, Vegetarian*
  • Female
  • Homocystinuria / diagnosis
  • Humans
  • Infant
  • Infant Nutrition Disorders / etiology*
  • Infant Nutrition Disorders / therapy
  • Male
  • Methylmalonic Acid / urine
  • Syndrome
  • Vitamin B 12 / administration & dosage
  • Vitamin B 12 / therapeutic use
  • Vitamin B 12 Deficiency / etiology*
  • Vitamin B 12 Deficiency / therapy


  • Methylmalonic Acid
  • Vitamin B 12