About 8,000 French people suffer from hemophilia: we take stock of this hemorrhagic disease, its symptoms and its treatments.
Three patients vaccinated against Covid-19 using the Pfizer / BioNtech vaccine have, to date, developed hemophilia. A “potential signal“to watch, according to the National Medicines Safety Agency (ANSM) which explains that at this stage,”the role of the vaccine in the occurrence of acquired hemophilia cannot be excluded“.
In detail, in its 15th pharmacovigilance report (covering the period from April 30 to May 13, 2021), the ANSM reports “among the effects already under specific surveillance, the analysis of a new case of acquired hemophilia (appearance of autoantibodies directed against coagulation factor VIII) over this period, bringing the total to 3 cases since the start of vaccination“. A potential adverse effect considered.”very rare“since it only concerns 3 patients out of more than 20 million injected doses.
Hemophilia: what is it exactly?
First thing to know: hemophilia is a rare genetic disease that affects around 8,000 French people (all severities combined). “It is a hemorrhagic disease which is linked to a coagulation defect“specifies Prof. Claude Négrier, specialist in constitutional and acquired hemorrhagic and thrombotic pathologies.
Coagulation is this natural phenomenon that takes place in the body in the event of a vascular breach – that is to say: when a blood vessel ruptures and there is a loss of blood . The formation of a blood clot (responsible for “blocking” the bleeding) results from a series of chemical reactions which involve many molecules, including proteins.
“Hemophilia exists in two forms“notes Prof. Négrier:
- L’hemophilia A is the most frequent since it represents about 85% of cases. “It occurs when there is a mutation in the gene that makes it possible to manufacture factor VIII, a protein made by the liver that is normally involved in the clotting process.“explains the specialist.
- L’hemophilia B is rarer (around 15% of cases): “this time, it is the gene that makes it possible to manufacture factor IX which is mutatedIt is also a specific protein, normally synthesized by the liver.
To know. There are obviously degrees in hemophilia: “hemophilia is said to be minor when the level of factor VIII or IX in the blood is between 5% and 40%; we speak of moderate hemophilia when it is between 1% and 5%, and severe hemophilia when this blood level is less than 1%“says Prof. Négrier. Unfortunately, severe hemophilia is the most frequent case.
What are the symptoms of hemophilia?
“Hemophilia is characterized by bleeding for longer, but not heavier“notes Prof. Négrier. In the event of a cut (with a kitchen knife, for example), the bleeding will last longer in a person who suffers from hemophilia.”People with hemophilia are not advised to engage in contact and combat sports – such as judo, boxing or hockey, for example, because there is this risk of prolonged bleeding.“emphasizes the doctor.
But hemophilia can also manifest itself through more surprising symptoms. So, “When learning to walk, young children with hemophilia can suffer from bleeding in the joints when they hit furniture, when they fall … explains the specialist. The blood collects inside the “articular bags”, like internal “bruises” (with the naked eye, there is no bleeding) and the joints can then appear swollen and painful, with difficulty to move.“The most commonly affected joints are the knees, ankles and elbows.
To know. “Today, thanks to advances in medicine, the life expectancy of a person with severe hemophilia is only about 10 years short of the average.“affirms Prof. Négrier.
Hemophilia: how is the diagnosis made and what are the treatments?
Diagnostic. If there is a known familial hemophilia, the diagnosis of the disease will be made from the birth of the child by measuring the two coagulation factors concerned (factor VIII and factor IX). “There may be a prenatal diagnosis“adds Prof. Négrier.
Otherwise, the diagnosis of the disease is first evoked in the face of hemorrhagic signs (abnormally long bleeding, painful and swollen joints in young children, etc.)
Treatments. The “basic” treatment of hemophilia (type A or type B) is based on the regular administration of the missing coagulation factor (factor VIII or factor IX) intravenously: on average, the administration is done 2 to 3 times a week, and it only lasts a few minutes. “It should be noted that the treatment can be done independently at home“specifies the specialist.
The “on demand” treatment is used in an emergency – for example: when you cut yourself with a piece of glass or when you have just fallen in the street. “This involves injecting factor VIII or IX in a very concentrated way with a syringe“explains Prof. Négrier.
Hemophilia: on the research side … Monoclonal antibodies are a new class of drugs that may soon become widespread for patients with hemophilia A. “These drugs increase the clotting process without replacing the missing protein: it is estimated that they can replace about 10% of the biological activity of factor VIII, developed by Prof. Claude Négrier. The administration is easier since it consists of a subcutaneous injection, once a week and then once every 15 days.“
Thanks to Prof. Claude Négrier, coordinator of the Rare Diseases of Constitutional Bleeding Diseases Health Sector (MHEMO) and Head of the Biological Hematology and Clinical Hemostasis Department at the Hospices Civils de Lyon (HCL).
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