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Updated: Mar 9, 2026
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Measurement of Factor V Activity in Human Plasma Using a Microplate Coagulation Assay
Published on: September 9, 2012
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Factor X Friuli Coagulation Disorder: Almost 50 Years Later
Antonio Girolami1, Elisabetta Cosi1, Claudia Santarossa1
11 Department of Medicine, University of Padua Medical School, Padua, Italy.
Summary
Factor X (FX) Friuli is a rare bleeding disorder identified in 1969. This genetic defect, caused by a specific mutation, presented diagnostic challenges but revolutionized FX deficiency diagnosis.
Area of Science:
- Hematology
- Genetics
- Clinical Diagnostics
Background:
- Factor X (FX) Friuli, discovered in 1969-1970, is a rare inherited bleeding disorder.
- Initial studies involved international collaboration, leading to varied diagnoses including FVII, FX, and combined deficiencies.
Observation:
- Patients exhibited a unique clotting profile: prolonged partial thromboplastin time and prothrombin time, but normal Russell viper venom clotting time.
- The use of anti-FX antisera was crucial for accurate diagnosis.
- Over four decades, 12 homozygotes and 102 heterozygotes were monitored.
Findings:
- Six homozygotes died; causes included HIV infection and hepatitis B liver cirrhosis.
- Bleeding severity was moderate, correlating with FX levels (4-5% considered normal).
- Molecular analysis identified the causative mutation as Pro343Ser in exon 8.
- Chimeric FX Friuli mice models aided research into FX levels and mortality.
Implications:
- The study of FX Friuli significantly advanced the diagnostic approach for FX deficiencies.
- It highlighted the necessity of assaying FX across all diagnostic systems.
- FX Friuli remains unique to the Friuli Meduna River Valley, with no other global cases reported.
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