Pediatrics

Biography

Biography: Narjiss Aji

Abstract

Willebrand's disease (VWD) is a genetic bleeding disorder; a defect in the amount or structure of von Willebrand factor (VWF). VWF: An element of primary hemostasis, its two main roles are the adhesion of platelets to injured vessels, and the transport of factor VIII (FVIII). There are 3 types of variable severities: Type 1 (least severe): Partial quantitative deficit; VWF is made in less quantity, which can lead to factor VIII (FVIII) deficiency. Type 2 (more severe): the VWF is manufactured but does not fulfill its function. Type 3 (the most severe and the rarest): the deficiency in VWF is total and is associated with a constant and profound deficiency in FVII.

The diagnosis of VWD is a clinical and biological diagnosis, most often made in childhood or adolescence, especially in girls in puberty with menorrhagia.The clinical symptomatology is essentially cutaneous and mucosal, the interrogation must seek a history of hemorrhagic accidents as well as a family history of hemorrhagic symptomatology or known pathology of hemostasis. At the end of the interrogation, a haemorrhagic score can be established. This score developed by Tosetto has proven its relevance and has been approved and put online by the ISTH. There are pediatric adaptations.Type 3 VWD is defined by a total quantitative deficit of VWF. This is the most severe form of VWD. It represents less than 5% of the forms of the disease. The genetic abnormalities responsible for this type are nonsense mutations, allele expression defects or complete or partial deletions of the VWF gene. Transmission is recessive and symptomatic patients are homozygous or heterozygous.Routine biological tests are essential, but insufficient to detect VWD. They are carried out during the exploration of a hemorrhagic syndrome, the evaluation of the hemorrhagic risk preoperatively or in the presence of a family history of bleeding. These first-line biological tests include a complete blood count, prothrombin count (PT), thromboplastin time plus activator (PTA) and functional fibrinogen assay. Tests exploring primary hemostasis such as the measurement of platelet occlusion time PFA can be added as first intention. It is a non-specific test, but sensitive to qualitative and quantitative deficits of VWF. The specific biological tests, three in number, are to be carried out on the same sample, plasma VWF activity, called ristocetin cofactor activity, the antigen VWF assay and the coagulant FVIII assay.In VWF type 3 there is a total quantitative deficit. The antigen and the activity of the vWF are collapsed and the level of factor VIII is very low.To make a definitive diagnosis of VWD it is sometimes necessary to repeat the assays at different times.At present it is impossible to cure VWD, apart from accidents and situations at risk of bleeding, in the majority of cases, correction of VWF deficiency is not necessary, especially in the case of minor bleeding that has dried up. spontaneously. However, it is important to follow simple preventive measures.Type 3 patients do not respond to desmopressin, so VWF concentrates alone (Wilfactin*) or VWF concentrates in combination with FVIII (Wilstart*) are used. These treatments are instituted: Either in a curative way in order to treat an unforeseen hemorrhagic accident or, in a preventive way (before a scheduled surgery for example).

Conclusion: Willebrand's disease Type is a pathology of hemostasis, with a significant risk of bleeding, linked to a complete deficiency in vWF, it is the rarest and most severe type of VWD, its diagnosis is based on the clinic with a biological confirmation. The treatment is essentially preventive and is mainly based on the injection of VWF and FVIII concentrates