What is hemophilia?

Hemophilia is an inherited disorder in which one of the proteins (clotting factors) in the plasma is reduced or absent. These proteins, named by Roman numerals, work together in a complex system to help the body form a clot. When one of these factors is not present in normal levels, blood clotting is delayed, which results in prolonged bleeding. There are about 20,000 people with hemophilia in the United States.

All races and ethnic groups are affected. Although hemophilia is genetic, about one-third of babies with hemophilia have no known family history. This could be due to a new mutation, or change, in the gene that causes hemophilia.

Types hemophilia

There are two types of hemophilia:

  1. Factor VIII deficiency, or hemophilia A, is the most common type of hemophilia.
  2. Factor IX deficiency, or hemophilia B, is about four times less common.  

Hemophilia is classified by its level of severity. It may be mild, moderate, or severe, depending on the level of the blood clotting factors in the blood. People with no factor VIII or IX are considered severe, those with 1 to 5 percent of factor levels are considered moderate, and those with more than 5 percent levels are considered mild. About half of people with factor VIII deficiency have severe hemophilia.



The gene that causes hemophilia is carried on the X chromosome, so it is called a sex-linked disorder. Females have two X chromosomes, while males have one X and one Y chromosome. The Y chromosome does not contain the clotting factor gene. If a female inherits the hemophilia chromosome, the normal other X chromosome usually will enable her to make normal levels of factor. A female who has one affected X chromosome is called a hemophilia carrier. Carriers of hemophilia usually have normal factor levels, but in some cases, female carriers may have low levels of factor VIII or IX and may have bleeding symptoms that require treatment.

With every pregnancy a female carrier has a 50 percent chance of passing on the affected hemophilia X chromosome, which results in either having a son with hemophilia or a daughter who is a carrier. ALL daughters of men with hemophilia will be carriers since to be a female they must inherit the affected hemophilia X chromosome from their father. Sons of men with hemophilia will not be impacted because they inherit the unaffected Y chromosome from their father.

Signs and symptoms

Bleeding in hemophilia

Bleeding in hemophilia can occur anywhere. It can be external, such as mouth bleeding or bleeding from lacerations, or it can be internal, such as bleeding into a joint or muscle. People with hemophilia do not bleed faster than normal, but bleed for a longer time

Bleeding is often related to stages of development and to physical activity. For babies and toddlers, the most common sites of bleeding are the mouth and head trauma. Older children and adults most often have bleeding into joints and muscles, particularly ankles, knees and elbows.

Hemophilia may be suspected in a baby or young child if they have:

  • Prolonged bleeding after circumcision
  • Prolonged oozing from heel sticks or blood draws
  • Unusual raised bruises or large numbers of bruises
  • Mouth bleeding

Serious bleeding

Bleeding into the head accounts for most of the deaths from bleeding in all age groups. There may be no symptoms at all, so it is critical that the Hemophilia Treatment Center be called for any head trauma in a person with hemophilia. Treatment should be given first, before any diagnostic studies.

Headache, sleepiness, nausea, vomiting, sensitivity to light, and loss of consciousness could indicate bleeding into the head and should be treated immediately.

Frequent sites of bleeding

Joint bleeding  

Joint bleeding (hemarthrosis) is the most common site of bleeding and requires treatment early to prevent long-term damage to the joint.

Signs of joint bleeding include pain, swelling, heat and decreased motion of the joint. Bruising may not be present.

Bleeding into the muscles

Bleeding into the muscles can cause swelling, pain, warmth, and decreased motion in the muscle. Bruising may be visible, but often is not seen. Early treatment is important to prevent complications.

Testing and diagnosis

When you or your primary care provider suspect a bleeding disorder, it is important to be evaluated in a specialized center like the Hemophilia Treatment Center at Children’s Hospital of Philadelphia (CHOP). In addition to a complete medical history and physical examination, your child's physician may perform numerous blood tests, including screening coagulation tests, a blood count, and specific tests to measure levels of clotting factors. Your child's physician may also request details about your child's family history.


Treatment for hemophilia includes either directly replacing or mimicking the action of the missing or deficient clotting factor to prevent or treat bleeding. Specific hemophilia treatment is determined by the type and severity of hemophilia, age of child, and individual factors. Treatment decisions are made by the treatment team together with the patient and family.

Comprehensive care

Treatment of hemophilia should be provided by a comprehensive team of expert providers in a federally funded Hemophilia Treatment Center (HTC). Comprehensive care is a system of care that uses a team to provide optimal care for individuals with hemophilia and their families. The teams consist of professionals from several disciplines, including specialized hematologists, social workers, nurses, physical therapists and others, with the patient and family in the center of the team. These centers are supported and monitored by the Maternal Child Health Bureau of the US Health Services Administration and the Centers for Disease Control and Prevention. Patients receiving care at one of these HTCs have significantly better outcomes than those cared for outside of this system.


Hemophilia is a lifelong disease that requires the patient, family and treatment team to work together to maintain optimal health and quality of life. Significant and exciting advances are being made to improve treatment and minimize the impact that hemophilia has on the patient and family. New discoveries are taking place every day to help affected individuals lead active, healthy lives with good quality of life and a normal lifespan.