transcobalamin II deficiency
Findings
No curated finding names transcobalamin II deficiency yet. Everything below is reference data from Mondo, HPO and GenCC, not evidence about what affects it.
Definition
Transcobalamin deficiency (TC) is a disorder of cobalamin transport that usually presents during the first few months of life and is characterized by megaloblastic anemia, failure to thrive, vomiting, weakness and pancytopenia.
Definition from the Mondo Disease Ontology (MONDO:0010149), read 2026-09-29. CC BY 4.0.
- Inheritance
- Autosomal recessive inheritance
- Onset and course
- Infantile onset · Neonatal onset
HPO, annotations 2026-09-02
Features
22 features
What the disease is reported to present with, and how often among people who have it — never how often a feature means the disease. HPO, annotations 2026-09-02.
- Erythroid hypoplasiaHPOHP:0012133
- 1 of 1 reported patient
- Failure to thriveHPOHP:0001508
- 4 of 4 reported patients
- HepatomegalyHPOHP:0002240
- 1 of 1 reported patient
- IrritabilityHPOHP:0000737
- 1 of 1 reported patient
- Macrocytic anemiaHPOHP:0001972
- 1 of 1 reported patient
- Megaloblastic bone marrowHPOHP:0001980
- 1 of 1 reported patient
- Very frequent (80% to 99% of cases)
- Methylmalonic aciduriaHPO
Show the remaining 10
- Decreased circulating immunoglobulin concentrationHPOHP:0004313
- Frequent (30% to 79% of cases)
- Decreased total lymphocyte countHPOHP:0001888
- Frequent (30% to 79% of cases)
- Decreased total neutrophil countHPOHP:0001875
- Frequent (30% to 79% of cases)
- PancytopeniaHPOHP:0001876
- Frequent (30% to 79% of cases)
- ThrombocytopeniaHPOHP:0001873
- Frequent (30% to 79% of cases)
- HypotoniaHPOHP:0001252
- 2 of 4 reported patients
Genes
1 gene
Germline variants in the gene encoding each protein, as classified by GenCC submitters, each in their own words. Limited, disputed and refuted submissions are listed too.
- TCN2HGNC:11653
- Definitive · Ambry Genetics · Autosomal recessive · 2022
- Definitive · ClinGen · Autosomal recessive · 2025
- Definitive · G2P · Autosomal recessive · 2016
- Strong · Labcorp Genetics (formerly Invitae) · Autosomal recessive · 2023
- Strong · PanelApp Australia · Autosomal recessive · 2025
- Supportive · Orphanet · Autosomal recessive · 2021
Where it sits
Other names
2 names
Resolves to: transcobalamin II deficiency
- Also called
- inherited deficiency of transcobalaminTCN2 deficiency