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Trait

Reduced factor VIII activity

Reduced activity of coagulation factor VIII. Factor VIII (fVIII) is a cofactor in the intrinsic clotting cascade that is activated to fVIIIa in the presence of minute quantities of thrombin. fVIIIa acts as a receptor, for factors IXa and X.

HPO HP:0003125

Summary

Body system
Abnormality of blood and blood-forming tissues

6 genes linked to Reduced factor VIII activity

Changes in these genes cause rare conditions in which Reduced factor VIII activity is seen. Most people with this trait have none of those conditions, and a gene on this list says nothing about anyone's own genome.

GeneHow often it is seenConditions
GGCXgamma-glutamyl carboxylaseAlwaysIn 1 condition
SOS1SOS Ras/Rac guanine nucleotide exchange factor 1AlwaysIn 1 condition
VWFvon Willebrand factorAlwaysIn 2 conditions
F8coagulation factor VIIIVery often (80–99%)In 4 conditions
LMAN1lectin, mannose binding 1Very often (80–99%)In 2 conditions
MCFD2multiple coagulation factor deficiency 2, ER cargo receptor complex subunitVery often (80–99%)In 2 conditions

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.

Broader traits

Abnormal factor VIII activity

Where this comes from

  • The Human Phenotype Ontology, release 2026-09-01: the trait, its names, its definition and the genes linked to it. Find out more at hpo.jax.org.
  • Data release 2026.10.17-8666dff2.

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