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Case report
Transcobalamin deficiency: vitamin B12 deficiency with normal serum B12 levels
  1. Sanjeev Khera1,
  2. Suman Kumar Pramanik2 and
  3. Saroj Kumar Patnaik1
  1. 1 Pediatrics, Army Hospital Research and Referral, New Delhi, India
  2. 2 Hematology, Army Hospital Research and Referral, New Delhi, India
  1. Correspondence to Dr Sanjeev Khera; kherakherakhera{at}


Transcobalamin (TC) deficiency is a rare autosomal recessive inborn error of cobalamin transport which clinically manifests in early infancy. We describe a child with TC deficiency who presented with classical clinical and lab stigmata of inborn error of vitamin B12 metabolism except normal serum B12 levels. He was started on empirical parenteral cobalamin supplements at 2 months of age; however, the definitive diagnosis could only be established at 6 years of age when a genetic evaluation revealed homozygous nonsense variation in exon 8 of the TCN2 gene (chr22:g.31019043C>T).

  • haematology (incl blood transfusion)
  • vitamins and supplements
  • genetics

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  • Contributors SK did the literature search, established definitive diagnosis, manuscript writing, management and follow-up of the patient. SuKP and SaKP were instrumental in final proof reading of manuscript and management and follow-up of the child.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Patient consent for publication Parental/guardian consent obtained.

  • Provenance and peer review Not commissioned; externally peer reviewed.