Skip to main content

Hemophilia: Let’s start with the basics.

Hemophilia: Let’s start with the basics.

What is hemophilia? How do people get it? And why? If you’ve got questions, we’ve got answers.

What is hemophilia? How do people get it? And why? If you’ve got questions, we’ve got answers.

Profile view of Abdul, who lives with hemophilia A, sitting at the top of a slide, smiling and turned toward camera
Profile view of Abdul, who lives with hemophilia A, sitting at the top of a slide, smiling and turned toward camera

What is hemophilia?

To understand hemophilia, it’s 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.

Profile view of Abdul, who lives with hemophilia A, sitting at the top of a slide, smiling and turned toward camera
Profile view of Abdul, who lives with hemophilia A, sitting at the top of a slide, smiling and turned toward camera

How do people get hemophilia?

Most people living with hemophilia are 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.

Changing Hemophilia icon of a circle with an x representing a myth

All people who have hemophilia are diagnosed at birth.

Changing Hemophilia icon of a circle with a checkmark representing a fact

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.

Changing Hemophilia icon of a circle with an x representing a myth

All people who have hemophilia are diagnosed at birth.

Changing Hemophilia icon of a circle with a checkmark representing a fact

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.

Changing Hemophilia illustration representing 80 percent of people with hemophilia A and 20 percent with hemophilia B

2 Types of Hemophilia

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, moderate, or severe hemophilia—what do they mean?

Mild, moderate, or severe hemophilia—what do they mean?

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 FACT

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

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

HEMOPHILIA FACT

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

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

The spectrum of bleeding disorders.

Along with hemophilia A and B, 15 other bleeding disorders have been identified. What makes them different? Here’s an overview of each one:

What about inhibitors?

Find out why some people living with hemophilia develop inhibitors and what that means.

Women and hemophilia.

It’s a myth that only males are affected by hemophilia. Learn more about how women can be, too.

What about inhibitors?

Find out why some people living with hemophilia develop inhibitors and what that means.


Women and hemophilia.

It’s a myth that only males are affected by hemophilia. Learn more about how women can be, too.