Rare diseases · Sign or symptom

Decreased memory B cell proportion

HP:0030374

What it means

A reduction in the normal proportion of memory B cells (CD19+/CD27+) in circulation relative to the total number of B cells. Memory B cells develop from naive B cells. Upon antigen rechallenge, memory B cells rapidly expand and differentiate into plasma cells under the cognate control of memory Th cells (Phase IV).

Rare diseases that can present with this2

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

Decreased memory 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.