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transcobalamin II deficiency - Clinical Profile, Genes & Research | Kisho | Kisho

Rare Disease

transcobalamin II deficiency

MONDO:0010149

Also known as:TCN2 deficiencyinherited deficiency of transcobalaminTC 2 deficiency

Find Clinical TrialsTrials

Overview

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.

GeneticsAutosomal recessive · TCN2 (chr 22)

Clinical Trials1 registered

Clinical Presentation

Built from Human Phenotype Ontology (HPO) phenotype annotations and GeneReviews clinical descriptions. Features represent findings documented across known cases — not an exhaustive list of possible symptoms.

Features include always present findings: Enlarged liver (hepatomegaly), Erythroid hypoplasia, Failure to thrive, and Irritability and others; and common findings: Low muscle tone (hypotonia), Hyperhomocystinemia, Low red blood cell count (anemia), and Diarrhea and others. 24 total HPO annotations.

Organ System	Phenotype Count	Example Features
Blood and immune system	5	Low red blood cell count (anemia), Reticulocytopenia, Macrocytic anemia

Genetic Landscape

TCN2 function has not been fully characterized.

Transcobalamin II deficiency is caused by mutations in the TCN2 gene on chromosome 22.

Diagnosis

Genetic testing for TCN2 is available. Testing is considered confirmatory for diagnosis.

Prognosis

Phenotype severity distribution: 7 always present features, 6 common features.

Estimated prevalence: <1 in 1,000,000 (VERY_RARE).

Research Landscape

Sourced from ClinicalTrials.gov and PubMed. Publication types are classified using NLM-curated article metadata; research type breakdowns reflect the nature of published work for this disease.

1 clinical trial registered. Interventions under study include other interventions. Research is primarily sponsored by academic and government institutions.

13 publications have been identified in PubMed for transcobalamin II deficiency. Research spans Case Report / Case Series (62%), Basic Science / Preclinical (15%), and Other (8%).

Research Type	Count	% of Total
Patient case studies	8	62%

Data assembled from 8 of 12 sources · Last updated Sep 18, 2026, 12:36 PM UTC

MONDOHPOClinicalTrials.govFDAPubMedHGNCClinVarClinGenGeneReviewsOrphanetOMIMRUSP

Medical References

External Resources

OMIM

Online Mendelian Inheritance in Man

OMIM:275350

Orphanet

European rare disease database

Orphanet:859

GARD

Genetic and Rare Diseases Info Center

GARD:12338

Questions for Your Care Team

→Should my partner and I meet with a genetic counselor to discuss carrier status and family planning?
→Are any of the 1 active clinical trial a good fit for my situation?
→Are there specialists or centers of excellence for this condition in my area?
→Is there a patient registry I should consider joining?

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transcobalamin II deficiency

Overview

Clinical Presentation

Genetic Landscape

Diagnosis

Prognosis

Research Landscape

Medical References

External Resources

OMIM

Orphanet

GARD

Questions for Your Care Team

Questions for Your Care Team

Explore clinical features

Recent Publications

transcobalamin II deficiency

Overview

Clinical Presentation

Genetic Landscape

Diagnosis

Prognosis

Research Landscape

Medical References

External Resources

OMIM

Orphanet

GARD

Related Diseases

Questions for Your Care Team

Questions for Your Care Team

Explore clinical features

Recent Publications