Living with Transcobalamin II deficiency
A genetic condition in which the body cannot move vitamin B12 where it's needed, affecting growth, blood, and the nervous system.
Understanding Transcobalamin II deficiency
Cells without B12 cannot grow and divide well. Signs usually appear in the first weeks or months of life. They can include slow weight gain, vomiting, diarrhea, and mouth sores. The nervous system can be affected, and people often have megaloblastic anemia, in which red blood cells are too few and too large.
Signs & symptoms
Symptoms vary from person to person. GARD lists these among the most common:
- Low blood cell counts (pancytopenia)
- Low platelet count (thrombocytopenia)
- Low neutrophil count
- Abnormal bone marrow cells (megaloblastic)
- Acute kidney injury
- Slow weight gain and growth
Not everyone has every symptom. GARD's list comes from the Human Phenotype Ontology.
Diagnosis
- 1Talk with your doctor
Share the symptoms you've noticed, when they started and your family health history. Notes and photos can help.
- 2See a specialist
Specialists who may be involved include allergy and immune system specialists, blood and bone marrow specialists and genetic specialists.
- 3Consider genetic testing
Changes in TCN2 are linked to this condition. Genetic testing and counseling can help confirm a diagnosis and explain what it means for your family.
- 4Connect with expert centers
Immune Deficiency Foundation may keep lists of experts for this condition.
Care & treatment
- Care team
- Allergy and immune system specialists (allergists / immunologists); Blood and bone marrow specialists (hematologists); Genetic specialists (geneticists)
- Expert care
- Expert lists: Immune Deficiency Foundation
- Treatment
- GARD doesn't list specific treatments for this condition. Your care team will tailor care to your symptoms.
- Research
- Clinical trials and observational studies may be options. See the research section below.
General information, not medical advice. Your care team makes the decisions.
Everyday life
Living with a rare condition is easier with support.
- Connect with Immune Deficiency Foundation
- Keep notes on symptoms, changes and questions for appointments
- Ask about patient registries that help research
- Look into financial aid and travel resources for care visits
Quick facts
This condition is caused by changes in the TCN2 gene. It is autosomal recessive, so a child inherits a changed copy of the gene from each parent.
Also known as: inherited deficiency of transcobalamin; tc ii deficiency; tcn2 - transcobalamin ii deficiency; tcn2 deficiency; tcn2d; transcobalamin deficiency
Patient organizations
- Immune Deficiency FoundationPrimary immunodeficiency · United States
Broader rare-disease groups
- Global GenesRare Diseases · United States
- National Organization for Rare DisordersRare Diseases · United States
- Genetic AllianceRare Diseases · United States
- RARE FoundationRare Diseases · United States
You are more than your diagnosis
Perspectives from people navigating life with Transcobalamin II deficiency.
Explore research for Transcobalamin II deficiency
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