Hemophilia A and B: Causes, Diagnosis, and Management

Hemophilia is one of the most common inherited bleeding disorders. It happens when a person’s blood doesn’t clot properly because of missing or defective clotting factors. The two main types are hemophilia A, caused by a lack of factor VIII, and hemophilia B, caused by a lack of factor IX. A third, rarer type called hemophilia C results from low levels of factor XI. Hemophilia is usually inherited, meaning it’s passed from parents to children through genes. Since the genes for factors VIII and IX are located on the X chromosome, hemophilia mostly affects males, while females are typically carriers. However, females can also be affected in rare cases, such as with Turner syndrome or X-chromosome inactivation.Historically, hemophilia was known as the “royal disease,” as it appeared in the descendants of Queen Victoria. The condition was first clearly described by Dr. John Conrad Otto in the late 18th century and later studied genetically by Dr. Nasse.