Saad Ahmed MBBS, MD, MRCPI, FRCPath
Consultant Haematologist, Children’s Health Ireland at Crumlin
Haemophilia is an inherited reduction in clotting factor VIII (Haemophilia A) or clotting factor IX (Haemophilia B) that can result in bleeding and joint damage.
Haemophilia A and B are inherited bleeding disorders carried in the X chromosome, with haemophilia A affecting 1 in 5,000 boys and Haemophilia B affecting 1 in 30,000 boys worldwide. Ireland has a higher incidence of Haemophilia B, affecting 1 in 12,500 boys. Women can carry the haemophilia gene, and some have low clotting factor levels and bleeding.
Features and diagnosis of haemophilia
The diagnosis of haemophilia is usually made during childhood or early adult life, either after a family screening or during an investigation for unusual bleeding. Approximately 30% of new cases have no previous family history of haemophilia.
Bleeding in haemophilia depends on the level of clotting factor. Patients with clotting factor levels of more than 5% have mild haemophilia and bleed after significant trauma or surgery. In moderate haemophilia patients, clotting factor level range between 1% and 5% and bleed after minor trauma.
In severe haemophilia, the clotting factor level is less than 1%; and patients can bleed spontaneously, particularly in their joints and muscles.
Approximately 30% of new cases have no
previous family history of haemophilia.
Management of haemophilia: past, current and future
Until the 1960s, patients diagnosed with haemophilia had a median life expectancy of approximately 30 years, and the only treatments available were whole blood or fresh plasma.
The use of plasma concentrates of coagulation factors started in the 1970s and resulted in a significant reduction in bleeding and early deaths. The risk of HIV and/or hepatitis C infection due to contamination of clotting factor concentrates was very high in the 1980s and 1990s. This gave momentum to the development of laboratory-made recombinant factors which now largely replaced clotting factors extracted from blood.
Research going into haemophilia care
In the last 10 years, researchers developed recombinant clotting factors that last in the body 2–5x more than conventional clotting factors. A breakthrough in the treatment of haemophilia A is a protein manufactured in the laboratory and binds to the clotting proteins IX and X. It’s injected under the skin and partially replaces the function of clotting factor VIII and prevents spontaneous bleeding.
Currently, many gene therapy studies are using a modified virus to carry a normal or enhanced FVIII or FIX gene to the liver, allowing it to start making normal or semi-normal levels of the missing clotting factor. The future of haemophilia care is rapidly evolving and looks promising.
