[Von Willebrand disease. Molecular biology and diagnosis]. / Enfermedad de von Willebrand, biología molecular y diagnóstico.

BACKGROUND: Von Willebrand disease is the most common inherited disorder of the coagulation proteins in humans. There are three types: 1, 2A, 2B, 2N, 2M and 3. It is associated with mutations on chromosome 12 in the region p13.2, encoding the von Willebrand factor (VWF), which is synthesized in endothelial cells and megakaryocytes. DISCUSSION: The VWF gene has been characterised using molecular biology techniques, which have acquired an important role in diagnosis von Willebrand disease, as well as in the investigation of alterations in other genes, which may be involved in regulating the synthesis, processing, and secretion of VWF. However, there are still no strategies to integrate the molecular biology diagnostic tests available. Analysis of VWF multimers is a methodology that meets the characteristics for diagnosis, but it is not easy to standardise. Considering that even in tertiary centres in our country, von Willebrand patients do not have a definitive diagnosis, it is necessary to implement these methodologies to study and improve diagnosis. CONCLUSIONS: Von Willebrand disease is highly heterogeneous due to the molecular mechanisms that produce the various clinical and laboratory phenotypes. In Mexico there are few studies related to this disease; therefore it is essential to conduct a comprehensive study including clinical, basic, and special testing laboratory tests, in order to establish a correct diagnosis, develop new therapeutic approaches, and offer the appropriate medical care and genetic counselling.

Doença de von Willebrand e anestesia / Von Willebrand's disease and anesthesia

JUSTIFICATIVA E OBJETIVOS: A doença de von Willebrand ocorre devido à mutação no cromossomo 12 e é caracterizada por deficiência qualitativa ou quantitativa do fator de von Willebrand. A diversidade de mutações leva ao aparecimento das mais variadas manifestações clínicas possibilitando a divisão dos pacientes em vários tipos e subtipos clínicos. A coagulopatia se manifesta basicamente através da disfunção plaquetária associada à diminuição dos níveis séricos do fator VIII coagulante. O objetivo dessa revisão foi mostrar os cuidados relacionados aos pacientes portadores da doença de von Willebrand durante o período perioperatório. CONTEUDO: Foram definidas as características da doença de von Willebrand quanto à fisiopatologia, à classificação, ao diagnóstico laboratorial, ao tratamento atual e aos cuidados com o manuseio do paciente no período perioperatório. CONCLUSÕES: A doença de von Willebrand é o distúrbio hemorrágico hereditário mais comum, porém ela é subdiagnosticada pela complexidade da própria doença. A correta classificação do paciente, o uso apropriado da desmopressina e a transfusão do fator de von Willebrand são medidas fundamentais para a realização do procedimento anestésico bem-sucedido.

BACKGROUND AND OBJECTIVES: von Willebrand's disease is secondary to a mutation on chromosome 12, and is characterized by a qualitative and quantitative deficiency of the von Willebrand's factor. The diversity of the mutations is responsible for several different clinical manifestations, enabling the classification of several types and subtypes. The coagulopathy is manifested basically through a platelet dysfunction associated with a reduction in the serum levels of factor VIII. The objective of this review was to present the perioperative care of patients with von Willebrand's disease. CONTENTS: The physiopathology, classification, laboratorial diagnosis, and current treatment of von Willebrand's disease, as well as the perioperative management of these patients are discussed. CONCLUSIONS: von Willebrand's disease is the most common hereditary coagulopathy, but it is underdiagnosed due to the complexity of the disease itself. The right classification, proper use of desmopressin, and transfusion of von Willebrand's factor are fundamental for a successful anesthesia.

JUSTIFICATIVA Y OBJETIVOS: La enfermedad de von Willebrand ocurre debido a la mutación en el cromosoma 12 y se caracteriza por la deficiencia cualitativa o cuantitativa del factor de von Willebrand. La diversidad de mutaciones conlleva al aparecimiento de las más variadas manifestaciones clínicas posibilitando la división de los pacientes en varios tipos y subtipos clínicos. La coagulopatía se manifiesta básicamente a través de la disfunción plaquetaria asociada con la disminución de los niveles séricos del factor VIII coagulante. El objetivo de esa revisión fue mostrar los cuidados relacionados con las pacientes portadoras de la enfermedad de von Willebrand durante el período perioperatorio. CONTENIDO: Se definieron las características de la enfermedad de von Willebrand en cuanto a las fisiopatologías, la clasificación, al diagnóstico laboratorial, al tratamiento actual y a los cuidados con el manejo del paciente en el período perioperatorio. CONCLUSIONES: La enfermedad de von Willebrand es el disturbio hemorrágico hereditario más común, sin embargo ella está subdiagnosticada por la complejidad de la propia enfermedad. La correcta clasificación del paciente, el uso apropiado de la desmopresina y la transfusión del factor de von Willebrand son medidas fundamentales para la realización del procedimiento anestésico exitoso.

High prevalence of bleeders of unknown cause among patients with inherited mucocutaneous bleeding. A prospective study of 280 patients and 299 controls.

BACKGROUND AND OBJECTIVES: Mucocutaneous bleeding (MCB) is the main expression of inherited disorders of primary hemostasis. However, the relative prevalence of these disorders, their clinical differential diagnosis, and the proportion of patients with MCB of unknown cause (BUC) after an initial comprehensive laboratory testing are unknown. DESIGN AND METHODS: We studied prospectively 280 consecutive patients with MCB and 299 matched controls, using strict inclusion and exclusion criteria. A single physician recorded the clinical data in a bleeding score and estimated the severity of bleeding in clinical categories. Laboratory criteria for the diagnosis of von Willebrand's disease (VWD) and platelet function defects were established from reference values derived from controls. RESULTS: Fifty patients (17.9%) had VWD (type 1VWD=45, type 2=5). Platelet function defects and mild clotting factor deficiencies were found in 65 (23.2%) and 11 (3.9%) patients, respectively. Thirteen (11.5%) patients had combined defects. The remaining 167(59.6%) patients had BUC, with prolonged bleeding time in 18.6% as their only abnormality. All these disorders, including BUC, were clinically undistinguishable. Moreover, no relationship was found between the severity of bleeding and VWF/platelet function variables. INTERPRETATION AND CONCLUSIONS: The diagnostic efficacy of a first laboratory testing in patients with hereditary MCB is 40.4%. Most patients have a disease(s) of high prevalence but unknown pathogenesis. Concurrent bleeding disorders in the same patient are frequent. Our results support the proposal that low plasma VWF levels, but also platelet function defects, should be considered risk factors rather than unequivocal causes of hemorrhages.

Doença de von Willebrand na prática ginecológica e obstétrica / Von Villebrand's disease in gynaecologic and obstetric practice

A evolução e o manejo das mulheres que apresentam sangramento uterino anormal têm sido motivo de várias publicações. Distúrbios congênitos e adquiridos da hemostasia devem ser considerados no diagnóstico diferencial de menorragia e sangramento uterino anormal. A doença de von Willebrand, desordem sanguínea hereditária que afeta 1 a 3 porcento da população, pode ser sugerida pela anamnese, história menstrual e história familiar, pois há componente genético bem estabelecido. Os autores apresentam uma atualização sobre a doença de von Willebrand na prática ginecológica e obstétrica e acrescentam considerações quanto a fisiopatologia, classificação e diagnóstico; isto contribuirá para o clínico controlar sinais e sintomas que repercutem negativamente sobre a estrutura orgânica e funcional da mulher

Correlación clínica y de laboratorio en pacientes pediátricos portadores de enfermedad de von Willebrand / Clinical correlation and of laboratory in carrying pediatrics of disease of Von Willebrand

La Enfermedad de von Willebrand (EvW) es una coagulopatía frecuente en la población. La importancia de pesquisar los diferentes subtipos de esta enfermedad tiene relación con las diversas modalidades terapéuticas y la disminución del uso de hemoderivados. El objetivo de este trabajo fue analizar una población de pacientes pediátricos con diagnóstico de EvW, en control en nuestra Unidad y determinar el subtipo de EvW que presentaban, caracterizando a cada grupo en relación a sus antecedentes, severidad de su sintomatología y utilización de hemoderivados. Se encontró mayor frecuencia de pacientes con EvW tipo 1, con sintomatología hemorragípara variable en su frecuencia e intensidad. Se analiza la sobreutilización de hemoderivados en este grupo de pacientes al no conocer con precisión el tipo de EvW.

Empleo del DDAVP en el manejo de la enfermedad de Von Willebrand / Treatment of Von Willebrand´s disease with DDAVP

La enfermedad de Von Willebrand (EVW) es la coagulopatía heredable más frecuente en pediatría, causada por defectos cuantitativos o cualitativos de factor Von Willebrand (FVW). El tipo 1 concentra cerca del 75 por ciento del total de pacientes con esta patología. Para este grupo desde hace 20 años se utiliza la desmopresina (DDAVP) para el tratamiento de sangramientos espontáneos y para prevención de episodios hemorrágicos secundarios a procedimientos invasivos. Los objetivos de este artículo son: una revisión actualizada del uso de este medicamento en dicha coagulopatía y la difusión de esta alternativa terapéutica que permite evitar riesgos transfusionales además de disminuir los costos. Se revisa brevemente la clasificación y fisiopatología de los distintos tipos de von Willebrand para entender la elección de el tratamiento más apropiada. Incluimos un esquema simple y seguro para ser utilizado en aquellos pacientes respondedores a desmopresina.

Allelic frequencies of three VNTRs in intron 40 of the human von Willebrand factor gene in types 1, 2, and 3 von Willebrand disease patients and controls of a Brazilian population.

Intron 40 of the human von Willebrand factor (vWF) gene contains a polymorphic region with three variable-number tandem repeats (VNTRs), type (ATCT)n. In the present report, we evaluated the allelic frequencies of these three VNTRs in a population constituted by 51 Brazilian Caucasian and 25 Types 1, 2, and 3 von Willebrand disease (vWD) patients, and performed segregation analysis in eight families affected by vWD Types 1 and 2. Three pairs of primers were used to amplify independently nucleotides 1640-1794 (VNTR 3), 1890-1991 (VNTR 1), and 2215-2396 (VNTR 2) from intron 40. The observed heterozygosities (0.86, 0.66, and 0.66 for VNTRs 3, 1, and 2, respectively) were in accordance with the expected heterozygosities derived from the allele frequencies (0.81, 0.64, and 0.70, respectively). Although the three VNTRs were highly polymorphic, VNTR 3 showed the highest values of heterozygosity [Haemostasis 25 (1995) 264; Hum. Mol. Genet. 1 (1992) 287.].

Terapia transfusional com plasma e derivados / Transfusion therapy with plasma and derivatives

Nesta revisäo säo analisadas as principais indicaçöes para o uso do plasma e seus derivados. Particularmente, säo focalizadas a utilizaçäo dos fatores de coagulaçäo no tratamento das hemofilias e da doença de von Willebrand, e o uso terapêutico da albumina e das imunoglobulinas