Many people with hemophilia A can lead ordinary, active lives. Learning more about this genetic condition can support effective long-term management strategies.

Hemophilia A is a genetic condition that is present from birth. It can be inherited or de novo (caused by a genetic change that occurs during embryonic development). Like other types of hemophilia, hemophilia A prevents proper blood clotting.

This article explores the frequently asked questions about hemophilia A, including its causes, severity, and impact on quality of life.

Hemophilia A is one of two primary typesTrusted Source of hemophilia — the other is hemophilia B. Hemophilia A is a genetic condition that prevents the body from making enough of clotting factor VIII (factor 8). Clotting factors are proteins in the blood that are involved in coagulation (clot formation).

Clots are part of the body’s healing process. They control blood loss and create a matrix that supports tissue repair.

People with hemophilia A have a genetic change on the F8 gene of their X chromosome that affects the production of clotting factor VIII. Without enough clotting factor VIII, coagulation is interrupted. As a result, clots may not form, may form slowly, or may not be stable if they do form.

Hemophilia A is the most common typeTrusted Source of hemophilia.

Hemophilia A varies in severity, depending on how the F8 gene is altered. Genetic changes can result in a mild, moderate, or severe deficiency of clotting factor VIII. The lower the level of clotting factor VIII, the more serious the bleeding can be.

Mild hemophilia A, which involves clotting factor VIII levels of 6% to 40%,Trusted Source rarely causes spontaneous bleeding (episodes of internal hemorrhaging that result from an unknown cause or from everyday activities). Though it is considered mild, this type of hemophilia A will still result in prolonged or excessive bleeding as a result of minor tissue trauma.

Bleeding episodes are more common in severe hemophilia A. With clotting factor VIII levels of less than 1%Trusted Source, severe hemophilia A may periodically cause spontaneous bleeding.

The life span for someone with hemophilia A varies depending on the severity of the condition and on individual factors such as age, co-occurring conditions, and medical management.

Research suggests that hemophilia has an association with a lower life expectancy overall. In a 2020 study involving more than 1,000 men in the Netherlands, researchers found that the median life expectancy for those with hemophilia was 77 years — 6 years lower than the median for the larger population of men.

In a 2023 studyTrusted Source in the United States, researchers found that between 1999 and 2020, the median life expectancy for males with hemophilia increased from 54.5 to 65.5 years. However, racial disparities were significant, with a 12-year difference in the median age at end of life between non-Hispanic Black males (56 years) and non-Hispanic white males (68 years).

Hemophilia A is a genetic condition that is present from birth. It is not contagious, but it is hereditary, which means it can pass from a parent to a child.

Quality of life (QoL) is a measurement of how well a person feels. In hemophilia A, QoL varies depending on the severity of the condition and individual variables such as overall health, lifestyle habits, and treatment adherence.

A 2019 surveyTrusted Source found that health-related QoL among people with severe hemophilia A was low. The most common challenges that survey participants cited were pain, anxiety, depression, and physical limitations due to joint pain.

QoL in milder forms of hemophilia A may be higher. With treatment and safety measures, many people can maintain ordinary levels of activity and function.

Hemophilia A primarily affects males due to inheritance patterns. The condition appears on the X chromosome.

In females, two X chromosomesTrusted Source are present (XX), one from the father and one from the mother. Males have one X chromosome from their mother and a Y chromosome from their father (XY).

In females, an unaffected X chromosome can compensate for the F8 genetic change on the other X chromosome. However, because males have only one X chromosome, the altered F8 gene will affect the production of clotting factor VIII.

Females can still have factor VIII deficiency if the second X chromosome is not working or if both X chromosomes have the genetic change, but males are more likely to experience severe bleeding.

This means females with an F8 genetic change are less likely to have significant symptoms, while all males with an F8 change for hemophilia A will have clotting factor VIII deficiency.

Hemophilia A is an X-linked recessive traitTrusted Source. It requires two F8 genetic changes in females or a single F8 change in males.

For a trait to be considered dominant, it must always be present, even when a person has only one affected chromosome, regardless of their sex.

Clotting factor VIII deficiency in hemophilia A does not worsen with age. If a person does not receive treatment for the condition, the severity that is present at birth will remain consistent throughout the person’s life.

However, hemophilia A symptoms may become more noticeable as a result of natural age-related changes in the body, illness, chronic injury, or co-occurring medical conditions. Over time, spontaneous bleeds can cause long-term damage to some areas of the body, such as the joints.

Hemophilia A and von Willebrand disease are distinct conditions. Both arise from genetic changes that affect blood clotting, but the genes and clotting agents involved are different.

Von Willebrand disease is linkedTrusted Source to a genetic change in the von Willebrand gene (vWF), which causes a deficiency in von Willebrand factor, a glycoprotein that helps carry clotting factor VIII.

Most people with hemophilia A are born with an inherited genetic change. In about 30% of cases, however, hemophilia A is caused by a genetic change that occurs during embryonic development.

Even though many people can live ordinary, active lives with hemophilia A, the outlook is guardedTrusted Source. Even in mild cases, prolonged or excessive bleeding in certain areas of the body, such as the head, could be life threatening.

Hemophilia A affects the body’s ability to form blood clots. It is a genetic condition caused by a change in the F8 gene on the X chromosome.

With treatment and everyday safety precautions, many people with hemophilia A can lead active, ordinary lives. Quality of life and life expectancy can vary depending on factors such as the condition’s severity and a person’s age, lifestyle, and co-occurring medical conditions.