thrombocytopenia 3
Findings
No curated finding names thrombocytopenia 3 yet. Everything below is reference data from Mondo, HPO and GenCC, not evidence about what affects it.
Definition
An inherited thrombocytopenia caused by a variation in the FYB1 gene, characterized by small-platelet thrombocytopenia beginning in infancy, with variable mucocutaneous bleeding including petechiae, epistaxis, and heavy menstrual bleeding. Platelet studies in affected individuals reveal reduced pseudopodia formation, impaired integrin activation, increased basal P-selectin and PAC-1 expression, and reduced ability to upregulate activation markers following ADP stimulation. Megakaryocyte abnormalities, including reduced numbers of mature multilobulated megakaryocytes and impaired proplatelet development, reflect a defect in cytoskeletal organization linked to the loss of FYB1's adaptor function in integrin-mediated signaling.
Definition from the Mondo Disease Ontology (MONDO:0010120), read 2026-09-29. CC BY 4.0.
- Inheritance
- Autosomal recessive inheritance
- Onset and course
- Infantile onset · Juvenile onset · Childhood onset
HPO, annotations 2026-09-02
Features
13 features
What the disease is reported to present with, and how often among people who have it — never how often a feature means the disease. HPO, annotations 2026-09-02.
- Abnormal bleedingHPOHP:0001892
- 2 of 2 reported patients
- Decreased mean platelet volumeHPOHP:0005537
- 8 of 8 reported patients
- EpistaxisHPOHP:0000421
- 3 of 3 reported patients · Childhood onset
- 0 of 5 reported patients
- MenorrhagiaHPOHP:0000132
- 2 of 2 reported patients
- PetechiaeHPOHP:0000967
- 3 of 3 reported patients · Childhood onset
- 1 of 5 reported patients
Genes
1 gene
Germline variants in the gene encoding each protein, as classified by GenCC submitters, each in their own words. Limited, disputed and refuted submissions are listed too.
- FYB1HGNC:4036
- Strong · Labcorp Genetics (formerly Invitae) · Autosomal recessive · 2021
- Strong · PanelApp Australia · Autosomal recessive · 2025
- Moderate · ClinGen · Autosomal recessive · 2024
Where it sits
Other names
2 names
Resolves to: thrombocytopenia 3
- Also called
- FYB1-related thrombocytopeniaTHC3