Hemophilia overview
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Simrat Sarai, M.D. [2]
Overview
Hemophilia usually is inherited. "Inherited” means that the disorder is passed from parents to children through genes. People born with hemophilia have little or no clotting factor. Clotting factor is a protein needed for normal blood clotting. There are several types of clotting factors. These proteins work with platelets to help the blood clot. Platelets are small blood cell fragments that form in the bone marrow—a sponge-like tissue in the bones. Platelets play a major role in blood clotting. When blood vessels are injured, clotting factors help platelets stick together to plug cuts and breaks on the vessels and stop bleeding. The two main types of hemophilia are hemophilia A and hemophilia B. If you have hemophilia A, you're missing or have low levels of clotting factor VIII (8). About 8 out of 10 people who have hemophilia have type A. If you have hemophilia B, you're missing or have low levels of clotting factor IX (9). Rarely, hemophilia can be acquired. "Acquired” means you aren't born with the disorder, but you develop it during your lifetime. This can happen if your body forms antibodies (proteins) that attack the clotting factors in your bloodstream. The antibodies can prevent the clotting factors from working.[1]
Historical Perspective
Hemophilia was first described by Dr. John Conrad Otto, a Philadelphia physician in 1803 who wrote an account about "a hemorrhagic disposition existing in certain families." He recognised that the disorder was hereditary and that it affected mostly males and rarely females.
Classification
Hemophilia may be classified into three subtypes based on lack of functional clotting factors:hemophilia A , hemophilia B, Hemophilia C.
Pathophysiology
Development of hemophilia is the result of multiple genetic mutations. The genes involved in the pathogenesis of hemophilia include the F8 gene in hemophilia A and F9 gene in hemophilia B.
Causes
Hemophilia is caused by a mutation in a gene involved in the synthesis of clotting factor proteins.
Differentiating Hemophilia from other diseases
Hemophilia must be differentiated from other diseases that lead to spontaneous bleeding and bleeding following injuries or surgery such as von Willebrand disease, liver failure-early or end staged, thrombocytopenia, vitamin K deficiency, disseminated intravascular coagulation, uremia, congenital afibrinogenemia, factor V deficiency, factor X deficiency as seen in amyloid purpura, glanzmann's thrombasthenia, bernard-soulier syndrome, factor XII deficiency and C1INH deficiency.
Epidemiology and Demographics
The prevalence of hemophilia is estimated to be 20,000 cases annually. The incidence of hemophilia is estimated to be 1 in every 10,000 births ( or 1 in 5,000 male births) for hemophilia A and 1 in 50,000 births for hemophilia B.
Risk Factors
Common risk factors in the development of hemophilia are family history of bleeding and male gender.
Screening
Genetic counseling is recommended for hemophilia carrier families.
Natural History, Complications and Prognosis
Common complications of hemophilia include deep internal bleeding, joint damage from haemarthrosis, transfusion transmitted infection from blood transfusions, intracranial haemorrhage and hemophilic arthropathy. Depending on the severity and adequate treatment, the prognosis may vary.
History and Symptoms
Symptoms of hemophilia include excessive bleeding and easy bruising.
Physical Examination
Physical examination of patients with hemophilia is usually remarkable with signs of bleeding in the mouth from a cut or a bite or from cutting or losing a tooth, nosebleeds, heavy bleeding from a minor cut, bleeding from a cut that resumes after stopping for a short time, blood in the urine, blood in the stool, and large bruises.
Laboratory Findings
Laboratory findings consistent with the diagnosis of hemophilia include unaffected prothrombin time, prolonged partial thromboplastin time, unaffected bleeding time and unaffected platelet count.
CT Findings
On CT, hemophilia is characterized by haemorrhage into joints or soft-tissue.
Medical Therapy
The mainstay of therapy for hemophilia is blood clotting factor replacement therapy.