What is hemophilia?

Hemophilia is a rare and serious X-chromosome linked congenital bleeding disorder that affects the blood's ability to clot.

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 most 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.

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.

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.

Hemophilia with inhibitors differs from regular hemophilia. Not everyone who lives with hemophilia will develop an inhibitor, but they are not uncommon. 

Inhibitors are antibodies in the blood that react to infused factor. These antibodies stop (or inhibit) the factor from working and slow the clotting process. Inhibitors don’t exist at birth—they first appear only after replacement factor has been used. Inhibitors usually develop within the first 50-75 exposure days or during childhood but in rare cases can appear after years of treatment.

By combining our experience in protein design with collaboration in the global scientific community, our scientists are exploring innovative, long acting and subcutaneous treatment solutions for hemophilia and rare blood disorders. These solutions aim to improve clinical outcomes. They will be complemented by research into oral treatments and gene therapy.

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.

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 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.

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.