Seven Patients With Transcobalamin Deficiency Diagnosed Between 2010 and 2014: A Single-Center Experience

J Pediatr Hematol Oncol. 2017 Jan;39(1):38-41. doi: 10.1097/MPH.0000000000000685.


Transcobalamin deficiency (OMIM 275350) is a rare autosomal recessive disease presenting with nonspecific clinical features in early infancy. We report the clinical and laboratory manifestations of 7 children diagnosed with transcobalamin deficiency. All patients were admitted between 2 and 4 months of age with anemia, thrombocytopenia, and hyperhomocysteinemia. The most common complaints at admission were pallor, weakness, and poor feeding. Genetic analysis was performed in 5 patients and it revealed the same homozygous mutation. We initially treated all patients with intramuscular injections of a maximum of 1 mg cyanocobalamin (CN-Cbl) daily and with a final dose of 1 mg per week. Hemoglobin and platelet counts significantly decreased upon decrease or cessation of CN-Cbl therapy. The patients were reevaluated between 2 and 4 years of age and all had delay in speech and walking. In conclusion, 1 mg of intramuscular CN-Cbl every week suffices for hematological improvement but not for normal neurological development in patients who all had relapse due to decrease or cessation of treatment.

MeSH terms

  • Anemia / etiology
  • Anemia / therapy
  • Codon, Nonsense
  • Combined Modality Therapy
  • Developmental Disabilities / etiology
  • Diagnosis, Differential
  • Erythrocyte Transfusion
  • Female
  • Frameshift Mutation
  • Homozygote
  • Humans
  • Hyperhomocysteinemia / etiology
  • Infant
  • Male
  • Platelet Transfusion
  • Retrospective Studies
  • Sequence Deletion*
  • Thrombocytopenia / etiology
  • Thrombocytopenia / therapy
  • Transcobalamins / deficiency*
  • Transcobalamins / genetics
  • Turkey
  • Vitamin B 12 / therapeutic use
  • Vitamin B 12 Deficiency / diagnosis


  • Codon, Nonsense
  • Transcobalamins
  • Vitamin B 12