Haemophilia: inherited bleeding disorders, causes, symptoms, and treatments

Types and genetic causes

Three commonly recognized forms are:

• Haemophilia A – deficiency of factor VIII; the most frequent type.
• Haemophilia B – deficiency of factor IX; less common but clinically similar in many respects.
• Haemophilia C – deficiency of factor XI; usually milder and inherited differently (often autosomal recessive).

Haemophilia A and B are usually inherited in an X‑linked recessive pattern: the responsible genetic changes are on the X chromosome. Because males have one X chromosome, they are more frequently and more severely affected; females are typically carriers but can sometimes have symptoms (males are predominantly affected). Genetic changes or mutations may also occur for the first time in an individual without family history; about a third of cases arise from such new mutations. The condition is passed through genes and is a classic example of sex-linked inheritance. The Y chromosome does not carry the same clotting factor genes, which helps explain the sex-specific pattern.

Clinical features and diagnosis

Severity ranges from mild (bleeding mainly after surgery or major trauma) through moderate (bleeding with minor injuries) to severe (frequent spontaneous bleeding into joints, muscles, or internal organs). People with haemophilia do not bleed faster than others; they bleed for a longer time. Common signs include prolonged bleeding from cuts or dental work, repeated nosebleeds, deep bruises, and painful joint bleeds that can lead to long-term joint damage. Diagnosis is made by blood tests that measure clotting factor activity and identify which factor is deficient.

Treatment and management

Treatment aims to replace the missing factor or boost clotting and to prevent and manage bleeding episodes. Standard therapies include:

• Replacement therapy with clotting factor concentrates, given on demand or as regular prophylaxis.
• Desmopressin (DDAVP) for some people with mild haemophilia A to raise factor VIII temporarily.
• Antifibrinolytic medicines for mucosal bleeding and dental procedures.
• Supportive care: physiotherapy for joint health, careful planning for surgery and childbirth, and avoidance of certain medications such as NSAIDs that increase bleeding risk.

Historically, whole blood and plasma transfusions were used; later, cryoprecipitate and plasma-derived factor concentrates became standard. These blood-derived products carried risks of blood-borne infections in the past, prompting development of recombinant (synthetic) factor products and improved screening. In recent years, experimental gene therapies and long-acting factor formulations have shown promise in clinical trials, offering the potential to reduce bleeding and treatment burden.

History, social aspects and prevention

Recognition of haemophilia dates back centuries and gained public attention through royal and familial case histories. Advances in understanding clotting biochemistry and genetics during the 20th century led to the identification of clotting factors and the modern classification of the disease. Access to safe factor replacement and comprehensive care varies worldwide; specialist haemophilia treatment centers provide integrated services including genetic counselling, which can guide family planning and prenatal diagnosis. A person with the condition was traditionally called a haemophiliac, though contemporary guidance favors "person with haemophilia" to emphasize person-first language.

Important distinctions and facts

• Haemophilia A and B differ by the specific missing protein (factor VIII vs factor IX) but often require similar clinical approaches.
• Severity is defined by residual factor activity, not by the size of injuries.
• Newborn screening is not universal; family history and early bleeding are common reasons for investigation.

For reliable clinical guidance and patient resources, consult specialized haemophilia treatment centers and organizations that support people and families affected by this condition. Further reading and professional information can be found via clinical guidelines and patient advocacy sites (clotting information, bruise care, etymology, sex differences, genetic counselling, mutation details, X chromosome genetics, chromosome basics, genetics overview, general haemophilia resources).