Haemophilia is a rare and serious bleeding disorder. It affects the blood's ability to clot. Therefore, people with haemophilia bleed for a longer time than is normal. It is estimated that about 1 in 10,000 people are affected by haemophilia and. 450,000 people are living with haemophilia worldwide.
A person with haemophilia does not have enough coagulation factor in the body. It is typically passed down from parent to child, although about a third of cases are caused by a gene mutation.
There are two different types of haemophilia, A and B.
The most common type is haemophilia A (1 in 5000 male births), where a person does not have enough coagulation factor VIII (FVIII).
Haemophilia B is less common (1 in 25,000-30,000 male births). A person with this type of haemophilia does not have enough coagulation factor IX (FIX). Haemophilia B accounts for only 15–20% of total haemophilia cases.
The genes for both coagulation factors are found on the X chromosome. This is why it mainly affects males, who inherit an affected maternal X chromosome.
It is estimated that 30% of people living with haemophilia A and 1-5% of people living with haemophilia B develop inhibitors. Inhibitors is an immune response to infused factor replacement therapy, making treatment more challenging.