What causes hemophilia

Causes: how does hemophilia develop?

Author: PD Dr. med. G. Tallen, created on: 01/10/2014, last changed: 04/01/2020

Hemophilia is a hereditary disease. It is not contagious. Hereditary diseases such as haemophilia are caused by altered genetic makeup (gene e). Such changes can arise spontaneously for reasons that are still unknown (new mutation). More often, however, in haemophilia, the diseased gene is passed on from the mother to the male offspring. Haemophilia fathers always pass the gene on to their daughters. However, women are usually clinically healthy or have only mild haemophilia. Why this is so is described in the Genetics section.

Almost all of our physical characteristics are passed on from parents to their offspring through gene pairs. For example, the properties of certain blood proteins (coagulation factors), which are essential for normal endogenous hemostasis (blood clotting).
Numerous such coagulation factors are involved in a kind of chain reaction in the process of normal hemostasis. The factors are marked with Roman numerals. So-called hemophilia A is a form of the disease in which one or more mutations are present in the genetic make-up for factor VIII. In hemophilia B, the gene for factor IX is affected (see "Forms of diseaseAs a result, the coagulation activity of factor VIII or factor IX is reduced or completely absent. As a result, if left untreated, those affected tend to bleed more spontaneously, for example after injuries or during surgery, than healthy people.