Thrombosis: a major contributor to global disease burden.

BACKGROUND: Thrombosis is the common pathology underlying ischemic heart disease, ischemic stroke, and venous thromboembolism (VTE). The Global Burden of Disease Study 2010 (GBD 2010) documented that ischemic heart disease and stroke collectively caused 1 in 4 deaths worldwide. GBD 2010 did not report data for VTE as a cause of death and disability. OBJECTIVE: To review the literature on the global burden of disease caused by VTE. APPROACH AND RESULTS: We performed a systematic review of the literature on the global disease burden because of VTE in low-, middle-, and high-income countries. Studies from Western Europe, North America, Australia, and Southern Latin America (Argentina) yielded consistent results with annual incidences ranging from 0.75 to 2.69 per 1000 individuals in the population. The incidence increased to between 2 and 7 per 1000 among those aged ≥70 years. Although the incidence is lower in individuals of Chinese and Korean ethnicity, their disease burden is not low because of population aging. VTE associated with hospitalization was the leading cause of disability-adjusted life-years lost in low- and middle-income countries, and second in high-income countries, responsible for more disability-adjusted life-years lost than nosocomial pneumonia, catheter-related blood stream infections, and adverse drug events. CONCLUSIONS: VTE causes a major burden of disease across low-, middle-, and high-income countries. More detailed data on the global burden of VTE should be obtained to inform policy and resource allocation in health systems and to evaluate whether improved use of preventive measures will reduce the burden.

C1272F: a novel type 2A von Willebrand's disease mutation in A1 domain; its clinical significance.

Most mutations identified in 2A VWD patients are localized in the A2 domain, although missense substitutions have also been recognized in the A1 domain. We describe a novel heterozygous missense mutation in the A1 domain of VWF gene responsible for type 2A phenotype. Analysis of the complete exon 28 was carried out in a patient and his mother with life-long histories of moderate to severe bleeding and laboratory data of type 2A VWD. The analysis of exon 28 of VWF gene showed a 3815 G → T transversion resulting in C1272F mutation. It is probably associated with a group I mechanism according to patients' clinical symptoms, and, in the case of the propositus, the lack of clinical response to treatment with desmopressin. The mutation was not found in 100 normal alleles. This substitution affected the normal S-S bound between C1272 and C1458, which is involved in A1 loop structure, altering the normal multimerization and function of VWF. The VWFpp/VWF:Ag ratio in the propositus and his mother was >3, suggesting a shortened survival of VWF. We believe it is important to report the complete clinical phenotype corresponding to the new mutation to increase the knowledge in the clinical field.

Clinical features and laboratory patterns in a cohort of consecutive Argentinian patients with von Willebrand's disease.

BACKGROUND AND OBJECTIVES: von Willebrand's disease (vWD) is a bleeding disorder with variable clinical expression. Our aim was to classify patients with vWD and to determine the phenotype in their relatives. DESIGN AND METHODS: The types and subtypes, blood group frequency and its relevance, bleeding sites, response to the desmopressin (DDAVP) test, transfusion requirements and clinical features in type 1 and 2A families were determined in 1,885 patients. RESULTS: Our findings were: type 1: 91%, type 2A: 3.1%, severe vWD: 1.3%; type 2N: 1.6%; type low intraplatelet: 2.7%; combined 1+ 2N: 0.3%. Blood group O prevalence was 70.5%. Bleeding and transfusion requirements were not correlated to blood groups. The most frequent symptoms were: ecchymoses-hematomas and epistaxis and, in females over 13 years, also menorrhagia. Normal levels of factor VIII:C were found in 38.4% of the patients. DDAVP was infused in 567 patients with a good response in 80.6%. About 9% of our patients needed transfusion therapy. The diagnosis of von Willebrand's disease is more likely in subjects belonging to families with type 2A disease than in members of families with type 1 vWD in spite of these being symptomatic. INTERPRETATION AND CONCLUSIONS: These observations provide a good strategy to identify, classify and treat vWD patients without performing molecular assays.

An ELISA system to detect anti-factor VIII antibodies without interference by lupus anticoagulants. Preliminary data in hemophilia A patients.

BACKGROUND AND OBJECTIVES: Difficulties in identifying the coexistence of neutralizing anti-factor VIII antibodies (anti-fVIII) and lupus anticoagulant (LA) are mainly due to the interference of LA on anti-fVIII assays. Our aim was to reveal the presence of anti-fVIII using a system that is not affected by LA. DESIGN AND METHODS: We developed an enzyme-linked immunosorbent assay (ELISA) method that uses phospholipid-free recombinant factor VIII as the antigen. A monoclonal anti-fVIII was tested as a positive control, excluding non-specific binding by using two unrelated monoclonal antibodies. The ELISA was performed on hemophilic plasmas with anti-fVIII and negative LA (n=12) or without inhibitors (n=12). Two hemophilic plasmas with LA and presumably anti-fVIII were also assayed. Positive LA (n=12) and normal (n=10) plasmas were tested as negative controls. RESULTS: All (12/12) plasmas with anti-fVIII and 5/12 hemophilic plasmas without inhibitors were positive; LA and normal plasma controls were negative. INTERPRETATION AND CONCLUSIONS: Results presented here show that LA does not interfere with the anti-fVIII ELISA: However, the assay detects both neutralizing and non-neutralizing anti-fVIII antibodies, therefore a neutralizing effect must be confirmed through functional tests.

Anti-factor VIII inhibitors and lupus anticoagulants in haemophilia A patients.

In a study of 170 haemophilia A patients, 43 were found to have an inhibitory effect; seven had anti-factor VIII inhibitors (a-fVIII)(A), 18 had lupus anticoagulants (LAs) with a strong (B: 12) or weak (C: 6) time-dependent effect and 18 had no time-dependent LAs (D). The a-fVIII showed a neutralizing effect only against factor VIII and negative diluted Russell viper venom time (dRVVT). The LAs were diagnosed by dRVVT; the Staclot LA agreed with the dRVVT. During the study, three patients changed from an a-fVIII to an LA pattern; they also modified their clinical response. Our prevalence of a-fVIII was low (4%) and we found 21% of LA, with a high (50%) prevalence of time-dependent inhibition. This pattern raises the possibility of the coexistence of LA and a-fVIII, stressing the need to develop specific tests to identify a-fVIII and LA.

Behavior of diluted activated partial thromboplastin time in pregnant women with a lupus anticoagulant.

The present study was developed to verify whether a reduction in phospholipid concentration could increase the activated partial thromboplastin time (APTT) sensitivity to detect lupus anticoagulant (LA) during pregnancy. The authors studied 38 pregnant women (10 normal subjects and 28 patients with associated clinical complications) and 40 nonpregnant control subjects. Tests to detect LA, including APTT, platelet neutralization procedure (standard APTT), the kaolin clotting time, the diluted Russell viper venom test neutralized by lysed platelets, and factor assays, were performed. Positive results were found in 5 of 28 pregnant women with associated clinical complications. The APTT, using three different phospholipid concentrations (standard and more diluted cephalin), was performed on plasma samples and on its 1:1 mixture with normal plasma. The behavior of standard and diluted APTT was similar in negative LA pregnant women and nonpregnant control subjects. The mean values showed nonsignificant differences. Four of five pregnant women with positive LA findings had a prolonged APTT, which was not corrected by the addition of normal plasma using standard conditions. When diluted phospholipids were used, only one of them had a prolonged APTT that was corrected by the addition of normal plasma. Therefore, the highest sensitivity (80%) and specificity (100%) of the APTT to detect LA in pregnant women were obtained using the standard conditions.

Detección de portadores de hemofilia A: complementación de los estudios convencionales con el análisis de ADN / Detection of haemophilia A patients: complementation of the conventional study with DNA analysis

Con el propósito de evaluar la utilidad de complementar los estudos convencionales mediante el análisis del ADN con sondas extragénicas, para la detección de portadoras, estudiamos 60 individuos pertenecientes a 15 familias argentinas con uno (9) o más (6) miembros afectados de hemofilia. A severa. Realizamos el análisis de segregación de los enfermos polimórficos (RFLP), luego del tratamiento del ADN con TaqI/ST14, en 21 varones (15 hemofílicos) y 39 mujeres - 6 portadoras obligadas (PO) y 33 potenciales (PP) -, además de la determinación de la actividad del factor VIII (FVIII) y del antígeno del factor von Willebrand (vWFAg). La probabilidad de ser portadora de cada consultante, fue asignada según los métodos convencionales (antecedentes familiares y niveles de FVIII y vWFAg) y combinada con los resultados del análisis de los RFLP, expresados en términos de probabilidad. ST14 fue informativa en el 67% de las PO y en el 79% de las PP. El análisis de los RFLP permitió definir el estado portador (4,5% de riesgo de recombinación) en el 53% de las familias. En los casos con antecedentes previos, pudimos clasificar 5 de las 10 PP (1 portadora, 4 no-portadoras). El estado portador pudo ser excluido en 5 de 23 mujeres, parientes de hemofílicos esporádicos. En ciertos casos (5/10) observamos una falta de coincidencia entre el genotipo asignado y el fenotipo, probablemente por efecto del fenómeno de Lyon (inactivación al azar de uno de los cromosomas X), aunque no puede excluirse una recombinación entre el locus ST14 y el gen del FVIII. Los resultados del análisis de los RFLP fueron expresados en términos de probabilidad y combinados con los datos fenotípicos; las probabilidades así estimadas fueron bajas (< 0,13) o altas (> 0,95), contrariamente o lo obtenido al considerar exclusivamente los métodos convencionales (0,01 a 0,99). el análisis de segregación de los RFLP disminuye pues, considerablemente la incertidumbre sobre la probabilidad de ser portadora de cada consultante (AU)

Detección de portadores de hemofilia A: complementación de los estudios convencionales con el análisis de ADN / Detection of haemophilia A patients: complementation of the conventional study with DNA analysis

Con el propósito de evaluar la utilidad de complementar los estudos convencionales mediante el análisis del ADN con sondas extragénicas, para la detección de portadoras, estudiamos 60 individuos pertenecientes a 15 familias argentinas con uno (9) o más (6) miembros afectados de hemofilia. A severa. Realizamos el análisis de segregación de los enfermos polimórficos (RFLP), luego del tratamiento del ADN con TaqI/ST14, en 21 varones (15 hemofílicos) y 39 mujeres - 6 portadoras obligadas (PO) y 33 potenciales (PP) -, además de la determinación de la actividad del factor VIII (FVIII) y del antígeno del factor von Willebrand (vWFAg). La probabilidad de ser portadora de cada consultante, fue asignada según los métodos convencionales (antecedentes familiares y niveles de FVIII y vWFAg) y combinada con los resultados del análisis de los RFLP, expresados en términos de probabilidad. ST14 fue informativa en el 67% de las PO y en el 79% de las PP. El análisis de los RFLP permitió definir el estado portador (4,5% de riesgo de recombinación) en el 53% de las familias. En los casos con antecedentes previos, pudimos clasificar 5 de las 10 PP (1 portadora, 4 no-portadoras). El estado portador pudo ser excluido en 5 de 23 mujeres, parientes de hemofílicos esporádicos. En ciertos casos (5/10) observamos una falta de coincidencia entre el genotipo asignado y el fenotipo, probablemente por efecto del fenómeno de Lyon (inactivación al azar de uno de los cromosomas X), aunque no puede excluirse una recombinación entre el locus ST14 y el gen del FVIII. Los resultados del análisis de los RFLP fueron expresados en términos de probabilidad y combinados con los datos fenotípicos; las probabilidades así estimadas fueron bajas (< 0,13) o altas (> 0,95), contrariamente o lo obtenido al considerar exclusivamente los métodos convencionales (0,01 a 0,99). el análisis de segregación de los RFLP disminuye pues, considerablemente la incertidumbre sobre la probabilidad de ser portadora de cada consultante