Rare diseases · Sign or symptom

Decreased transitional B cell proportion

HP:0030380

What it means

Abnormal decrease of the transitional B cell subpopulation, commonly characterized as CD27-CD24hiCD38hi or CD27-IgMhiCD38hi, measured as percentage of total B cells in the blood, compared to a reference range for a given sex and age-group.

Rare diseases that can present with this1

Sometimes5–29%

1

The range is how often this sign appears among people diagnosed with each disease — it is not a probability of having any of them. Many of these signs also occur in common, non-rare conditions. A sign on this page is a conversation to have with a clinician, not a conclusion.

Part of the broader category

Abnormal transitional B cell proportion

Also called: Decreased proportion of CD19+CD38+IgM+ cells · Decreased proportion of transitional B cells

Decreased transitional B cell proportion

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This page uses the Human Phenotype Ontology (2026-06-23) — Human Phenotype Ontology Consortium, hpo.jax.org. Disease associations from Orphanet (INSERM), CC BY 4.0. Content is educational and is not medical advice.