What is the Difference Between Clotting Factor 8 and 9

The key difference between clotting factor 8 and 9 is that clotting factor 8 is a cofactor associated with clotting factor 9 to ensure the activation of clotting factor 10 in the coagulation process, while clotting factor 9 is a serine protease enzyme that cleaves and activates clotting factor 10 in the coagulation process.

Hemophilia is an inherited bleeding disorder. In this disorder, blood does not clot properly. It can lead to spontaneous blood loss following injuries or surgery. Blood usually contains many proteins called clotting factors that help to stop bleeding. People who suffer from haemophilia have low levels of either clotting factor 8 or clotting factor 9.

CONTENTS

1. Overview and Key Difference
2. What is Clotting Factor 8  
3. What is Clotting Factor 9
4. Similarities – Clotting Factor 8 and 9
5. Clotting Factor 8 vs 9 in Tabular Form
6. Summary – Clotting Factor 8 vs 9

What is Clotting Factor 8?

Clotting factor 8 is an essential blood clotting factor in the coagulation process. It is also known as an anti-hemophilic factor (AHF). The F8 gene encodes this clotting factor in humans. Any defect in this particular gene causes normally a coagulation disorder known as haemophilia A. Hemophilia A is a recessive X-linked coagulation disorder. Clotting factor 8 is generally produced by the sinusoidal cells of the liver and endothelial cells outside the liver. This clotting factor circulates in the blood in an inactive form, bound to another molecule called VWF (von Willebrand factor). When it is activated during an injury, it dissociates with the VWF factor. Later, the activated clotting factor 8 interacts with another clotting factor known as factor 9. This interaction ultimately results in blood clot formation after a chain of additional chemical reactions.

Moreover, clotting factor 8 is a cofactor for clotting factor 9a. In the presence of Ca²⁺ and phospholipids, it forms a complex. This complex converts clotting factor 10 to the activated form called clotting factor 10 a. Factor 10 a cleaves prothrombin in two places in order to make thrombin. Finally, thrombin converts soluble fibrinogen into insoluble strands of fibrin, which act as a blood clot. Furthermore, the high levels of clotting factor 8 also cause diseases such as deep vein thrombosis and pulmonary embolism.

What is Clotting Factor 9?

Clotting factor 9 is a serine protease enzyme that cleaves and activates clotting factor 10 in the coagulation process. Clotting factor 9 belongs to a peptidase family called S1. Deficiency of this protein causes haemophilia B, which is also known as Christmas disease. Clotting factor 9 was discovered in 1952 when a young boy named Stephen Christmas was found to be lacking this clotting factor.

The clotting factor 9 is encoded by the F9 gene in the X chromosome. Recombinant factor IX injection is used to treat Christmas disease. Furthermore, some rare mutations can cause the hyper-clotting activity of clotting factor 9. This can result in clotting diseases such as deep vein thrombosis. In addition to that, clotting factor 9 is also on the World Health Organization’s List of Essential Medicines.

What are the Similarities Between Clotting Factor 8 and 9?

• Clotting factors 8 and 9 are involved in the coagulation cascade reaction.
• Both clotting factors 8 and 9 are proteins.
• They are produced by the liver.
• Clotting factors 8 and 9 associate with each other to convert clotting factor 10 to its active form.
• The low levels of both clotting factors cause a clotting disorder called hemophilia.
• The high levels of both clotting factors also cause a clotting disorder called deep vein thrombosis.
• The genes for both clotting factors are located in X chromosomes.
• The mutations of both these genes cause X-linked recessive diseases.
• Both clotting factors are on the World Health Organization’s List of Essential Medicines.

What is the Difference Between Clotting Factor 8 and 9?

Clotting factor 8 is a cofactor that associates with clotting factor 9 to ensure the activation of clotting factor 10 in the coagulation process, while clotting factor 9 is a serine protease enzyme that cleaves and activates clotting factor 10 in the coagulation process. Thus, this is the key difference between clotting factor 8 and 9. Furthermore, a low level of clotting 8 causes hemophilia A disease, while a low level of clotting factor 9 causes hemophilia B (Christmas) disease.

The below infographic presents the differences between clotting factor 8 and 9 in tabular form for side by side comparison.

Summary – Clotting Factor 8 vs 9

Coagulation cascade reaction helps stop bleeding. This process is carried out by specific proteins known as clotting factors. Clotting factors 8 and 9 are both involved in the coagulation cascade reaction. Clotting factor 8 is a cofactor that associates with clotting factor 9 to ensure the activation of clotting factor 10 in the coagulation process. Clotting factor 9 is a serine protease enzyme that cleaves and activates clotting factor 10 in the coagulation process. So, this summarizes the difference between clotting factor 8 and 9.

Reference:

1. SI, Chavin. “Factor VIII: Structure and Function in Blood Clotting.” American Journal of Hematology, U.S. National Library of Medicine.
2. “Blood Clotting Factor 9.” An Overview | ScienceDirect Topics.

Image Courtesy:

1. “Fviii 2R7E” By Mattkosloski – Own work (CC BY 3.0) via Commons Wikimedia
2. “Coagulation in vivo” By Dr Graham Beards – Own work (Based on Figure 7.5 on page 167 of “Blood Science: principles and pathology” by Andrew Blann and Nessar Ahmed, Publishers Wiley Blackwell (2014) ISBN:978-1-118-35146-8) (CC BY-SA 3.0) via Commons Wikimedia