Traits

Traits linked to TCN2

transcobalamin 2

The Human Phenotype Ontology links 27 traits to TCN2, by body system: features seen in people with one of the gene's rare conditions.

Abnormality of blood and blood-forming tissues

Trait	How often it is seen
Erythroid hypoplasia	Always
Macrocytic anemia	Always
Megaloblastic bone marrow	Always
Decreased blood lymphocyte number	Often (30–79%)
Low blood cell count	Often (30–79%)
Low blood neutrophil count	Often (30–79%)
Low number of red blood cells or hemoglobin	Often (30–79%)
Low platelet count	Often (30–79%)
Reticulocytopenia	Not recorded

Abnormal cellular phenotype

Trait	How often it is seen
Abnormality of chromosome stability	Very often (80–99%)
Decreased circulating antibody level	Often (30–79%)
Decreased circulating IgA concentration	Often (30–79%)
Decreased circulating IgG concentration	Often (30–79%)
Decreased circulating IgM concentration	Often (30–79%)

Abnormality of the nervous system

Trait	How often it is seen
Irritability	Always
Ataxia	Not recorded
Intellectual disability	Not recorded
Lethargy	Not recorded

Abnormality of the digestive system

Trait	How often it is seen
Enlarged liver	Always
Diarrhea	Often (30–79%)
Vomiting	Often (30–79%)

Abnormality of the musculoskeletal system

Trait	How often it is seen
Low muscle tone	Often (30–79%)
Muscle weakness	Not recorded

Laboratory abnormality

Trait	How often it is seen
Methylmalonic aciduria	Always
Elevated blood homocystine	Often (30–79%)

Abnormality of the genitourinary system

Trait	How often it is seen
Acute kidney injury	Very often (80–99%)

Growth abnormality

Trait	How often it is seen
Faltering weight	Always

How often is among people with one of the gene's conditions, the most often across them, as the Human Phenotype Ontology records it. These pages describe traits and the research behind them; they are not a diagnosis, and a doctor or genetic counsellor is the person to ask about symptoms.

Where this comes from

The Human Phenotype Ontology, release 2026-09-01: the traits linked to TCN2 and how often each is seen. Find out more at hpo.jax.org.

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