What is hemophilia?

Hemophilia is a rare and serious X-chromosome linked congenital bleeding disorder that affects the blood's ability to clot, meaning that people with hemophilia bleed for a longer time than normal.

To understand hemophilia, it is helpful to know how the body normally works when it comes to stopping a bleed. When a person bleeds, 13 different proteins—called clotting factors—work together to form a blood clot.

In people living with hemophilia, one of the clotting factors is missing or reduced, which prevents this process from working. They have trouble forming blood clots—so it’s harder to stop bleeds when they happen.

People living with hemophilia are typically born with it. In the majority of these cases, it is passed to a child from the mother's side of the family. Sometimes, a person may develop hemophilia without any family history. In fact, nearly one-third of hemophilia cases are not inherited and have no family history of the disease. Since the genes for coagulation factors are on the X chromosome, hemophilia mainly affects males who inherit an affected maternal X chromosome.

Due to a lack of bleeding at birth or because the family doesn't have a history of hemophilia, some people who have hemophilia are not diagnosed as newborns.

of people with hemophilia have hemophilia A. Also known as factor VIII (8) deficiency, it is caused by a lack of the clotting factor known as factor VIII.

of people with hemophilia have hemophilia B. Also called factor IX (9) deficiency, it’s caused by a lack of—you guessed it—factor IX. 

Mild hemophilia means a factor VIII or IX level ranging from 5% up to 40% of normal blood levels

Moderate hemophilia refers to factor VIII or IX level ranging from 1% up to 5% of normal blood levels

Severe hemophilia means a person has a factor VIII or IX level below 1% of normal blood levels

Hemophilia A affects 1 in 5000 male births in the United States.

Since hemophilia and rare bleeding disorders are associated with several types of coagulation factors, there are different treatments. Current therapies are administered by infusion therapy injected into a vein or administered subcutaneously.

Replacement therapy can be given to combat a bleeding episode that is in progress. Or, it can also be administered at home on a regular schedule to help prevent bleeding episodes. For some people living with hemophilia, they must receive continuous replacement therapy.

Haemophilia research

We combine our experience in protein design with collaborations in the global scientific community to discover and develop effective and safe medicines for people with hemophilia and other rare bleeding disorders.

Our scientists are exploring innovative, long-acting and subcutaneous treatment solutions for hemophilia and rare blood disorders. These solutions are aimed at reducing the current treatment burden and improving clinical outcomes. They will be complemented by research into oral treatments and gene therapy.

We strive for offering better quality of life to people living with hemophilia and other bleeding disorders.

We often work in partnerships to discover novel targets and innovative compounds and technologies that address unmet medical needs. 

Explore our ambitious R&D pipeline.

Along with hemophilia A and B, 15 other bleeding disorders have been identified. What makes them different?

People with factor VII deficiency have low levels of factor VII in their blood. It’s one of the most common rare bleeding disorders, occurring in 1 in 300,000 to 500,000 people. Factor VII deficiency is inherited from both parents and occurs equally in men and women.

Factor VIII deficiency (hemophilia A) means a person has low levels of factor VIII in their blood. It affects mostly males who inherit it from their mothers, but in about 1/3 of people with hemophilia A, there is no family history and the cause is a gene mutation.

People with factor IX deficiency (hemophilia B) have low levels of factor IX in the blood. Hemophilia B is inherited and affects mostly males. It occurs in 1 in 30,000 live male births.

Factor XIII deficiency means a person has low levels of factor XIII in their blood. It occurs in only 1 in every 5 million people. It can occur in both men and women and is usually inherited from both parents, but can also develop later in life.

In von Willebrand disease (vWD), a person either doesn’t have the normal level of an important protein or the protein doesn’t work as it should—so their body can’t form a stable clot. 1 in every 100 people has some form of the disease. It’s inherited from one or both parents and affects men and women equally.

Factor I deficiency means a person has problems with a protein called fibrinogen, which is needed to help the body form a stable clot. Factor I deficiency includes afibrinogenemia, hypofibrinogenemia, dysfibrinogenemia and hypodysfibrinogenemia and occurs in 1 in every 1 million people.

Afibrinogenemia means a person has no factor 1 (fibrinogen) in their blood, so their body can’t form a stable clot. It is inherited from both parents and can occur in both men and women.

A person with hypofibrinogenemia has lower levels of factor 1 (fibrinogen) in their blood, so their body can’t form a stable clot. It affects both men and women and is usually inherited from both parents, but can also develop later in life.

Dysfibrinogenemia means that a person has normal levels of factor 1 (fibrinogen), but it doesn’t work as it should. It occurs equally in men and women and is usually inherited from one parent, but can also develop as a person gets older.

With Factor II deficiency, a person lacks enough Factor II in their blood to form a stable clot. It is one of the rarest inherited bleeding disorders. Studies have shown a higher incidence of Factor II deficiency among Latinos.

People with factor V deficiency have low levels of factor V in the blood so their bodies cannot form a stable clot to stop a bleed. It occurs in 1 in every 1 million people, is inherited from both parents and affects both men and women.

Factor X deficiency means a person has low levels of factor X in their blood. It occurs in 1 in every 500,000 to 1 million people. It is inherited from both parents, but can also develop later in life.

People with factor XI deficiency have low levels of factor XI in their blood. Factor XI deficiency occurs in 1 in every 100,000 people, is inherited from either parent and occurs in both men and women.

In Glanzmann’s thrombasthenia (GT), glycoprotein (a protein that helps platelets stick together to form a plug and stop bleeding) is defective or not present at all. GT is inherited from both parents and can occur in both men and women.

With Bernard-Soulier syndrome, a person’s platelets do not stick to an injured blood vessel wall, due to a defect in glycoprotein (a protein that helps platelets form a plug and stop bleeding). Bernard-Soulier syndrome is inherited from both parents and can occur in both men and women.

Platelets need granules to form a plug and stop bleeding. In platelet storage pool deficiency, the granules don’t work properly and platelets cannot form a plug to stop bleeding. This disorder is usually inherited from one or both parents and occurs in both men and women.

Acquired hemophilia (AH) is different because it’s not inherited. Instead, AH develops later in life in people with no personal or family history of bleeding disorders. AH is extremely rare and occurs when the immune system develops an antibody, or inhibitor, against its own coagulation factor, frequently factor VIII.