Rare diseases · Sign or symptom
Decreased total B cell count
Low B cell count
HP:0010976
What it means
The absolute number of B cells in the blood, per microlitre is below the lower limit of normal of the reference range for the appropriate sex and age-group.
Plasma B cells differentiate from B cells and secrete large amounts of antibodies.
Rare diseases that can present with this17
Very common80–99%
6- Agammaglobulinemia-microcephaly-craniosynostosis-severe dermatitis syndrome
- Atypical/leaky severe combined immunodeficiency due to partial RAG defect
- Cernunnos-XLF deficiency
- Combined immunodeficiency due to DOCK8 deficiency
- Deficiency in anterior pituitary function-variable immunodeficiency syndrome
- T-B-NK+ severe combined immunodeficiency due to DCLRE1C deficiency
Common30–79%
8- Activated PI3K-delta syndrome
- Activated PI3K-delta syndrome 1
- Activated PI3K-delta syndrome 2
- ALG12-CDG
- Combined immunodeficiency with facio-oculo-skeletal anomalies
- Congenital progressive bone marrow failure-B-cell immunodeficiency-skeletal dysplasia syndrome
- STAT1-related autoimmune enteropathy and endocrinopathy-susceptibility to chronic infections syndrome
- T-B-NK- severe combined immunodeficiency due to adenosine deaminase deficiency
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
Also called: B cell deficiency · B cell lymphopenia · B lymphocytopenia · CD19 lymphocytes low · Decreased B cell count · Reduction in B cell number
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Start free with EleplanThis 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.