Types of Hemophilia
Hemophilia is mainly classified according to which specific blood clotting factor is deficient or malfunctioning in the body.
1. Hemophilia A (Classical Hemophilia)
Hemophilia A is the most common type, accounting for roughly 80%–85% of all cases. It occurs when the body produces insufficient or defective Clotting Factor VIII (Factor 8). The severity of bleeding depends directly on the level of Factor VIII activity circulating in the bloodstream.
2. Hemophilia B (Christmas Disease)
Hemophilia B occurs when the body has low or absent levels of Clotting Factor IX (Factor 9). It was historically termedChristmas Diseaseafter Stephen Christmas, the first British patient in whom this specific factor deficiency was clinically described in 1952.
3. Hemophilia C (Factor XI Deficiency)
A rarer form caused by a deficiency of Factor XI. Unlike types A and B, Hemophilia C is inherited as an autosomal condition and affects both males and females equally, typically causing mild bleeding following major surgeries or dental extractions.
Classification by Severity
Both Hemophilia A and B are medically categorized into three degrees of severity based on laboratory factor assay measurements:
- Severe Hemophilia (< 1% Factor Activity): Frequent spontaneous bleeding episodes, particularly into large weight-bearing joints (knees, ankles, elbows) and deep muscles, requiring regular prophylactic factor replacement therapy.
- Moderate Hemophilia (1% – 5% Factor Activity): Occasional spontaneous bleeding; prolonged bleeding following minor injuries, falls, sprains, or dental procedures.
- Mild Hemophilia (5% – 40% Factor Activity): Rarely bleeds spontaneously. Prolonged bleeding occurs primarily during major surgery, dental extractions, or severe physical trauma.