Platelet- and plasma-derived factor Va are absolutely essential for thrombin generation catalyzed by the prothrombinase complex, a 1:1 stoichiometric complex of the serine protease factor Xa and the nonenzymatic cofactor, factor Va, assembled on an appropriate membrane surface in the presence of calcium ions. Two whole blood pools of the procofactor, factor V, exist: approximately 75% circulates in the plasma as a single chain inactive molecule, while the other 25% resides in platelet α-granules in a partially proteolytically-activated state. Our laboratory demonstrated that the platelet-derived cofactor originates following endocytosis of plasma-derived factor V by megakaryocytes, the platelet precursor cells, via a two receptor system including an uncharacterized, specific factor V receptor and low density lipoprotein receptor related protein-1. Following endocytosis factor V is physically and functionally modified and trafficked to the platelet α-granule from where it is released upon platelet activation at sites of vascular injury. The first goal of this dissertation was to define how factor V endocytosis changes over the course of megakaryocyte development. Hematopoietic multipotential stem cells were isolated from human umbilical cord blood and subjected to ex vivo differentiation into megakaryocytes. Megakaryocyte differentiation was assessed by flow cytometry using fluorescently-labeled antibodies against megakaryocyte- and platelet-specific markers and factor V directly conjugated to a fluorophore over 12 days. Differentiation was confirmed by a decrease in a stem cell marker (CD34) and an increase in a mature megakaryocyte marker (CD42) and coincident with factor V endocytosis. Live cell imaging verified differentiation and permitted the observation of proplatelet formation, the precursor to circulating platelets. Analogous experiments verified the trafficking of factor V into proplatelet extensions. Factor V is a highly glycosylated protein: potential roles of these glycans may be endocytosis and trafficking by megakaryocytes. We previously demonstrated that factor V endocytosis is mediated by the light chain region of the procofactor. This region of factor V contains three glycans - one high mannose and two complex N-linked glycans. In the second part of this dissertation, a role for the complex N-linked glycans at Asn1675 and Asn2181 of the factor V light chain in factor V endocytosis by megakaryocytes was assessed. Exoglycosidases were used to selectively trim the complex N-linked glycans on human factor V under native conditions. Treatment with neuraminidase removed 100% of the sialic acid residues on the factor V light chain as demonstrated by gel electrophoresis and mass spectrometry. Treatment with β-1,4-galactosidase removed 69% of the galactose residues at Asn1675 and 100% at Asn2181. Glycosidase-treated factor Va behaves similarly to untreated factor Va in thrombin generation assays suggesting that cofactor activity is unaltered by glycan trimming. In addition, glycan removal had no effect on factor V endocytosis by megakaryocyte-like cells. These observations suggest that complex N-linked glycans on the factor V light chain are not important for factor Va cofactor activity or factor V endocytosis by megakaryocyte-like cells, which strongly suggests that they have a role in trafficking.

At sites of vascular injury, the critical blood clotting enzyme thrombin is generated from prothrombin via Prothrombinase, a macromolecular, Ca2+-dependent enzymatic complex consisting of the serine protease factor Xa and the non-enzymatic cofactor factor Va, assembled on the membranes of activated platelets. Platelets regulate thrombin formation by providing specific binding sites for the components of Prothrombinase and by releasing a platelet-derived factor V/Va molecule that is more procoagulant than its plasma counterpart and partially resistant to proteolytic inactivation. This dissertation identifies and characterizes the subpopulation of platelet-derived factor V/Va that is responsible for the observed protease resistance, and the mechanism by which Prothrombinase bound to platelets differs from a model system using vesicles composed of 75% phosphatidylcholine (PC) and 25% phosphatidylserine (PS), PCPS vesicles. Previous studies have demonstrated that activated platelets release a dissociable pool of factor V/Va and a non-dissociable, membrane-bound pool, which is covalently attached to the platelet membrane through a glycosylphosphatidyl inositol (GPI) anchor. Data described herein demonstrate unequivocally that the pool of platelet-derived factor V/Va that is resistant to proteolytic inactivation by activated protein C is provided exclusively by the non-dissociable GPI-anchored pool. Further, although this factor Va pool is susceptible to proteolysis by plasmin, the fragments formed are associated with sustained and increased cofactor activity. These observations indicate that tethering of factor Va to the membrane surface via a GPI anchor imparts resistance to proteolytic inactivation and sustained thrombin generation at sites of vascular injury. For several years it has been known that Prothrombinase assembled on PCPS vesicles does not mimic that bound to platelets. While both enzymes cleave prothrombin at Arg271 and Arg320 to form thrombin, prothrombin activation proceeds via the prethrombin-2 pathway (initial cleavage at Arg271) on the platelet surface, in contrast to the meizothrombin pathway (initial cleavage at Arg320) on PCPS vesicles. Using thrombin active site inhibitors, we demonstrate that the preference for either pathway is dictated by the conformation in which prothrombin is bound by the membrane-bound enzyme. The prethrombin-2 pathway of prothrombin activation catalyzed by platelet-bound Prothrombinase is a direct consequence of configuring prothrombin in a proteinase-like state resulting in the exposure of a pseudo-active site that can be stabilized by active site thrombin inhibitors. Conversely, prothrombin is preferentially configured in the zymogen-like state on PCPS vesicles where the meizothrombin pathway is preferred. Additional support for the differential assembly of Prothrombinase on the platelet surface is provided by observations made using prethrombin-1, an intermediate formed by cleavage of prothrombin at Arg155 by the formed thrombin. Prethrombin-1 is converted into fragment-2 and thrombin by platelet-bound Prothrombinase at a substantially higher rate than vesicle-bound Prothrombinase. The decreased rate of prethrombin-1 activation in the model system is due, in part, to inhibition of the vesicle-bound enzyme by the fragment-2 generated in the reaction. Taken together, these data not only provide important molecular insights into the mechanisms by which Prothrombinase bound to activated platelets at sites of vascular injury regulates the procoagulant response to effectively support robust thrombin generation, but also provides potential mechanistic sites that could be targeted therapeutically.

Background: Escherichia coli (E.coli) O86a:K61 belongs to the Enteropathogenic E. coli (EPEC) group of pathogens. Acute gastroenteritis affects 2-4 billion people annually and EPEC is associated with 10-40% of hospitalized diarrhea cases globally. Coagulation Factor (F) V circulates as an inactive procofactor (Mr 330kDa) which upon thrombin activation to the active cofactor, FVa, functions in prothombinase to accelerate prothrombin to thrombin conversion by 300,000-fold. The ability of E.coli O86a:K61 to cause intestinal hemorrhage is of interest because previous research demonstrated that during E.coli O86a:K61 sepsis in baboons, a dose-dependent inactivation of FV was observed as the bacterial dose increased. These results suggested a secreted E.coli protease may have mediated this effect on FV. This research has focused on the purification, identification, and characterization of a secreted E. coli O86a:K61 protease that inactivates FV. The final partially-purified protease inactivated FV to a 250kDa product by immunoblotting, and possessed a 900-fold increase in specific activity versus FV in human plasma compared to the culture supernatant. At least 3 proteins were observed upon SDS-PAGE. Proteolytic inactivation of FV was activated by up to 500-fold with β-mercaptoethanol and 2-fold with 1M urea. The protease was heat stable retaining all of its activity versus FV after 1h at 70°C or 80°C, and partial activity (50%) at 95°C. Proteolysis of FV was blocked by 90% with alpha-1-protease inhibitor; however, the protease was resistant to 1.5 mM PMSF, and unaffected by E64, or iodoacetamide. FV is a major regulator of the coagulation process and its inactivation by the secreted E.coli protease would be expected to result in a net bleeding tendency which may contribute to the mucosal hemorrhage observed in humans with associated hemorrhagic colitis. Proteolytic inactivation of FV is predicted to result in decreased bacterial containment by host fibrin thereby increasing pathogen survival and growth. FV inactivation by the secreted E.coli protease may be part of a novel pathogenic virulence mechanism that deregulates the blood coagulation process to enhance bacterial infectivity and transmission. / UOIT

Intro/Aims: Venous thromboembolism (VTE) is a common complication in cancer patients. The role of thrombophilic polymorphisms in cancer related VTE remains poorly explored. Aim 1 of this study was to determine if Factor V Leiden (G1691A), Prothrombin (PT) G20210A or methylenetetrahydrofolate reductase (MTHFR) C677T are associated with the increased occurrence of VTE in adult oncology subjects compared to nononcology subjects. Aim 2 of this study was to determine if cancer patients with the MTHFR C677T polymorphism who are treated with antimetabolite therapy have an increased incidence of VTE compared to cancer patients who are treated with other chemotherapy.Setting/Methods: A descriptive, comparative, retrospective chart analysis was utilized for this study in an outpatient hematology, oncology clinic in Southern Arizona. Enrolled were 100 adult subjects (age 18 - 85) with documented history of VTE (27 subjects with cancer and 73 noncancer). Subjects were evaluated for Factor V Leiden, PT G20210A, and MTHFR C677T prior to the study. Eleven subjects were treated with antimetabolite chemotherapy and 8 subjects were treated with other chemotherapy.Results: The overall polymorphism frequency for Factor V Leiden was 21%, PT G20210A 4%, and MTHFR C677T 50%. Factor V Leiden was found in 11.1% of cancer subjects and 24.7% of noncancer subjects. Prothrombin G20210A was found in 3.7% of cancer subjects and 4.1% of noncancer subjects. MTHFR C677T was present in 25.9% of cancer subjects and 58.9% of noncancer subjects. No statistical significance was observed between subjects treated with an antimetabolite and positive for MTHFR C677T compared with those treated with other types of chemotherapy.Conclusion: Analysis of the data collected in this study demonstrated overall higher rates than the expected frequencies of all polymorphism for both the cancer and noncancer patients with documented VTE. In this small retrospective study, the only significant finding was that the MTHFR C677T polymorphism was more prevalent in the noncancer group.Currently, there are no specific guidelines for VTE prevention in the outpatient oncology setting. Identification of risk factors, including prothrombotic mutations may reduce risk of VTE and provide guidance for prophylactic treatment recommendations in the outpatient setting.

nÃo hà / As doenÃas trombÃticas constituem um sÃrio problema na saÃde mundial. Diversas desordens hereditÃrias, que afetam o sistema fisiolÃgico anticoagulante, estÃo atualmente estabelecidas como fatores de risco para a ocorrÃncia do evento trombÃtico. Dentre estes o fator V Leiden à o mais freqÃente. A associaÃÃo entre alteraÃÃes no gene do fator V e a ocorrÃncia de eventos trombÃticos desencadeou o desenvolvimento de diversas pesquisas. Neste estudo, 100 pacientes portadores de eventos trombÃticos, atendidos no ambulatÃrio de Hematologia do Centro de Hematologia e Hemoterapia do Cearà - HEMOCE/SESA/UFC, foram analisados para a detecÃÃo da presenÃa do fator V Leiden. O grupo controle consistiu de 110 voluntÃrios sadios. A freqÃÃncia encontrada na populaÃÃo controle foi de 2,7% (03/110), enquanto que nos pacientes trombofÃlicos foi de 9% (09/100). Destes, 77,8% (07/09) eram do sexo feminino e 22,2% (02/09) do sexo masculino e a cor predominante foi a parda [66,7% (06/09)]. A faixa etÃria mais freqÃente foi entre 26 e 33 anos [33,4% (03/09)]. Do total dos pacientes portadores do fator V Leiden, 88,9% (08/09) apresentaram trombose venosa profunda e 11,1% (01/09) trombose arterial com recorrÃncia do evento trombÃtico de 22,2% (02/09). A correlaÃÃo entre a presenÃa do evento trombÃtico/presenÃa do fator V Leiden e o uso de contraceptivo oral foi de 71,4% (05/07). Das pacientes portadoras e que usaram contraceptivo oral nÃo ocorreu o aborto. A localizaÃÃo do primeiro evento trombÃtico, nos portadores, foi predominantemente nos membros inferiores [88,9% (08/09)] e 11,1% (01/09), nas artÃrias coronÃrias. Em 44,4% (04/09) havia um ou mais fatores de risco/morbidade associado. A freqÃÃncia da mutaÃÃo encontrada no estado do Cearà mostrou-se inferior aos dados obtidos na regiÃo de Botucatu (SP) - 12% e ao estudo de Benson, em Atlanta (EUA)- 12,4 e ainda menor que os encontrados na regiÃo de Campinas (SP)- 20% e à populaÃÃo com ancestral europeu-18%. A diferenÃa entre pacientes trombofÃlicos e populaÃÃo controle nÃo foi estatisticamente significante (p=0,19), mas o risco estimado para o evento trombÃtico foi de 2,46.

Orientador: Ana Terezinha Guillaumon / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Ciencias Medicas / Made available in DSpace on 2018-08-07T00:25:35Z (GMT). No. of bitstreams: 1 Paschoa_AdilsonFerraz_D.pdf: 1209751 bytes, checksum: 841d1a79e90d1ef1c6bb14b58b807236 (MD5) Previous issue date: 2006 / Resumo: O tromboembolismo venoso (TEV) afeta de 1 a 3 indivíduos por mil habitantes/ano. O conhecimento atual das trombofilias permite a associação com cerca de 40% dos casos de TEV. Há controvérsias quanto ao valor da pesquisa laboratorial de trombofilia para o benefício dos doentes com tromboembolismo venoso. Procuraram-se as variáveis preditivas para a pesquisa positiva de trombofilia e avaliar o impacto desses resultados nas decisões clínicas. Foram avaliados 84 doentes consecutivos com TEV confirmado por métodos de imagem no período entre janeiro de 2001 e novembro de 2003. Após o período previsto de anticoagulação definido por critérios clínicos, os doentes foram submetidos à pesquisa das principais causas de trombofilia. Os resultados laboratoriais permitiram a dois examinadores independentes reavaliar caso-a-caso a indicação de ¿mudança de conduta¿, caracterizada pela interferência no tempo de profilaxia secundária ou ¿atenção especial¿ para medidas de maior vigilância diante de situações de risco ou para a extensão da pesquisa aos familiares assintomáticos. A trombofilia foi encontrada em 35 dos 84 casos (41,66%), sendo que em 27 (32,12%) havia uma causa genética. O fator V Leiden foi a alteração mais freqüente (15,47%), seguida do conjunto de deficiência dos anticoagulantes naturais (11,9%). Não houve diferença significativa da freqüência de trombofilia relacionada à faixa etária nem diferença de idade de aparecimento do primeiro evento trombótico entre doentes trombofílicos e não trombofílicos. Houve significância estatística para ocorrência de trombofilia nos doentes com tromboflebite superficial, recorrência e na associação com fatores de risco não cirúrgicos. A ¿mudança de conduta¿ foi atribuída a 6 dos 84 doentes (7,14%), estatisticamente significativa para aqueles com recorrência em relação aos que tiveram apenas um episódio de TEV. A ¿atenção especial¿ foi atribuída a 34 dos 84 casos (40,47%).A tromboflebite superficial de aparecimento espontâneo, a ocorrência de TEV relacionada a causas não cirúrgicas e a recorrência foram os principais achados preditivos de trombofilia. A ¿mudança de conduta¿ aplicou-se a uma pequena porcentagem de doentes, e refletiu predominantemente a confirmação da necessidade de prolongamento da profilaxia secundária. A ¿atenção especial¿ diante de situações de risco e a extensão da profilaxia primária a familiares de primeiro grau assintomáticos expostos a situações de risco parecem-nos a melhor indicação para a pesquisa laboratorial da trombofilia. Palavras-chave: trombofilia, fator V Leiden, mutação G20210A, proteína S, proteína C, antitrombina, hiperhomocisteinemia, anticorpos antifosfolípides, tromboembolismo venoso / Abstract: The venous thromboembolism (VTE) affects 1 to 3 individuals per a thousand habitants/year. Nowadays its possible to associated VTE with a cause of thrombophilia in about 40% of patients. There are some inconclusive points about the real benefit of the laboratorial investigation on thrombophilia for patients with VTE. We tried to identify the variables that point to the positive test results and the impact of these results on clinical decisions.The screening for the more common causes of thrombophilia was applied to 84 consecutive patients with VTE confirmed by image examination between January 2001 and November 2003. After test results, two independent observers evaluated, in a case by case basis, the indication of a ¿change on prophylaxis¿, in order to modify the period of anticoagulant intake (secondary prophylaxis), or ¿special attention¿ when considering to have a higher medical surveillance before risk situations or for the extension of the research to the first degree asymptomatic relatives.Thrombophilia was found in 41.66% (35/84), and in 32.12% (27/84) it involved agenetic cause. The factor V Leiden was the more prevalent alteration, identified in 15.47% of the cases, followed by the natural anticoagulants disfunction (11.9%). There was no significative difference of thrombophilia frequency between ages, nor a difference of age in the onset of the first thrombotic event between thrombophilic and non-thrombophilic patients. There was a higher prevalence of thrombophilia in patients with superficial thrombophlebitis of spontaneous onset, in cases of recurrence and when associated with non-surgical predisponent factors. The ¿change on prophylaxis¿ resulted in 7.14% (6/84), and there was statistically significance for patients with recurrent episodes when compared to patients with just one. The ¿special attention¿ was applied in 40.47% (34/84). Spontaneous superficial thrombophlebitis, occurrence of VTE related to nonsurgical causes and recurrence, were the main findings which suggested thrombophilia. The ¿change of prophylaxis¿ was applied to a small percentage of patients. The ¿special attention¿ for risk situations and the extension of the primary prophylaxis to the asymptomatic family members seem to be the best indication for the laboratorial research on thrombophilia. Key words: thrombophilia, factor V Leiden, G20210A mutation, protein C, protein S, antithrombin, hyperhomocysteinaemia, antiphospholipids antibodies, venous thromboembolism / Doutorado / Cirurgia / Doutor em Cirurgia

CoordenaÃÃo de AperfeiÃoamento de NÃvel Superior / CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / RESUMO As doenÃas trombÃticas constituem um sÃrio problema de saÃde pÃblica. Diversas desordens hereditÃrias e ambientais, que afetam o sistema fisiolÃgico anticoagulante, estÃo atualmente estabelecidas como fatores de risco para a ocorrÃncia do evento trombÃtico. Dentre os fatores hereditÃrios, as mutaÃÃes G1691A do gene do fator V e G20210A do gene da protrombina sÃo os mais freqÃentes. A associaÃÃo entre estas alteraÃÃes genÃticas e a ocorrÃncia de eventos trombÃticos desencadeou o desenvolvimento de diversas pesquisas. Neste estudo, 189 pacientes portadores de eventos trombÃticos, atendidos no ambulatÃrio de Hematologia do Centro de Hematologia e Hemoterapia do Cearà - HEMOCE/SESA/UFC, foram analisados para a detecÃÃo da presenÃa das mutaÃÃes G1691A do gene do fator V e G20210A do gene da protrombina. O grupo controle consistiu de 349 voluntÃrios. A freqÃÃncia encontrada na populaÃÃo controle foi de 2% (7/349) para a mutaÃÃo do fator V e 1,7% (6/349) para a mutaÃÃo da protrombina, enquanto que nos pacientes trombofÃlicos a freqÃÃncia destas mutaÃÃes foi de 9% (17/189) e 2,1% (4/349), respectivamente. Dentre os fatores hereditÃrios, apenas a mutaÃÃo do fator V foi significante (p<0,001). Considerando os fatores ambientais de risco, o tabaco, idade > 40 anos e sexo feminino apresentaram significÃncia estatÃstica (p<0,001). Os riscos foram estimados em anÃlises pareadas e nÃo pareadas para o fator V de Leiden (4,8; 5,3; 9,8), tabaco (17,6; 14,9; 33,3), idade idade > 40 anos (2) e sexo feminino (3,7 e 4,1). Os fatores de risco para eventos trombÃticos no Cearà foram tabagismo, idade > 40 anos, sexo feminino, e a mutaÃÃo G1691A do fator V.foram associados com o desenvolvimento de trombose no estado do CearÃ. / Thrombotic diseases are a serious problem for public health. Several hereditary and environmental factors, that affect physiological anticoagulant system, have been nowadays well established as risk factors for thrombosis. Among hereditary factor V Leiden and prothrombin G20210A mutation are the most frequents. The association between several modifications on factor V gene and prothrombin gene in the development of thrombotic events has brought about future searches. In this study, 189 patients with thrombosis attended at the Hematology and Hemoterapy Center of Cearà state âHEMOCE/ Brazil, were analyzed to find out the presence of factor V Leiden and prothrombin G20210A mutation The control group was made up 349 healthy volunteers. In this study, the frequency found of factor V Leiden the control population was of 2% (7/349) and in the patients was 9% (17/189) while the frequency found of prothrombin G20210A mutation the control population was of 1,7% (6/349) and in the patients was 2,1% (4/189). Among hereditary factors only factor V Leiden was significant statistic (p<0,001). Among environmental factors studied, tabagism, age > 40 anos and femele were significant statistic (p<0,001). The ODDS RATIO of the risk factors with significant statistic were factor V de Leiden (4,8; 5,3; 9,8), tabaco (17,6; 14,9; 33,3), age > 40 years old (2) and female (3,7 e 4,1). Our results demonstrate that factor V Leiden, tabagism, age > 40 years old and female were associated with development trombosis in CearÃ.

No description available.

Objetivo: Avaliar o impacto de fatores de risco no desenvolvimento de eventos tromboembólicos em pacientes com lesão medular. Métodos: Estudo observacional, prospectivo e cruzado. Pacientes elegíveis (n=100) tinham lesão medular por trauma raquimedular e mais de 18 anos. O grau de lesão sensorial e motora foi avaliado com base na escala ASIA (ASIA Impairment Scale - AIS). Amostras de sangue foram coletadas para exames de coagulação, hemogramas, análises bioquímicas e laboratoriais. Exames de ultrassonografia foram realizados nos sistemas venosos superficial e profundo dos membros inferiores. Experimentos de PCR em tempo real foram realizados com o intuito de investigar mutações nos genes da protrombina (G20210A) e do fator V de Leiden (G1691A). Resultados: O principal achado deste estudo foi a maior ocorrência de Trombose Venosa Profunda (TVP) em pacientes com fator V de Leiden e hiperhomocisteinemia. Não houve associação entre Lesão Medular por TVP, Tromboembolismo Venoso (TEV) e trombofilia. Não houve também relação com lúpus anticoagulante e anti-cardiolipina. Conclusões: Houve importante diferença na incidência de TVP em pacientes com Lesão Medular, tanto aguda quanto crônica (após um ano da lesão). A investigação de trombofilia deve ter como base os fatores clínicos, fatores de risco para TVP e história familiar de trombose / Objective: Evaluate the impact of risk factors in the development of thromboembolic events in patients with spinal cord injury. Design: Observational, prospective and cross study. Eligible patients (n=100) had spinal injury (SI) by spinal cord injury (SCI), older than 18 years of age. The degree of motor and sensory lesion was evaluated based on ASIA Impairment Scale (AIS). Blood samples were collected for coagulation exams, hemogram, laboratory and biochemical analyses. Ultrasonography analyzes were performed from deep and superficial venous systems of lower limbs. Quantitative real-time PCR experiments were performed in order to investigate mutations in the prothrombin (G20210A) and Leiden factor V (G1691A) genes. Results: The main finding of this study was the higher occurrence of Deep Venous Thromboembolism (DVT) in patients with Leiden factor V and hyper homocysteinemia. There was no association between SI for DVT, venous thromboembolism (VT) and thrombophilia. Also, there was no relation between lupus anticoagulant and anti-cardiolipin. Conclusions: There is an important difference in the incidence of DVT in patients with SI by acute SCI and after 1 year. The conduct of the investigation for thrombophilia should be based on clinical factors, risk factors for DVT and family history of thrombosis

Objetivo: Avaliar o impacto de fatores de risco no desenvolvimento de eventos tromboembólicos em pacientes com lesão medular. Métodos: Estudo observacional, prospectivo e cruzado. Pacientes elegíveis (n=100) tinham lesão medular por trauma raquimedular e mais de 18 anos. O grau de lesão sensorial e motora foi avaliado com base na escala ASIA (ASIA Impairment Scale - AIS). Amostras de sangue foram coletadas para exames de coagulação, hemogramas, análises bioquímicas e laboratoriais. Exames de ultrassonografia foram realizados nos sistemas venosos superficial e profundo dos membros inferiores. Experimentos de PCR em tempo real foram realizados com o intuito de investigar mutações nos genes da protrombina (G20210A) e do fator V de Leiden (G1691A). Resultados: O principal achado deste estudo foi a maior ocorrência de Trombose Venosa Profunda (TVP) em pacientes com fator V de Leiden e hiperhomocisteinemia. Não houve associação entre Lesão Medular por TVP, Tromboembolismo Venoso (TEV) e trombofilia. Não houve também relação com lúpus anticoagulante e anti-cardiolipina. Conclusões: Houve importante diferença na incidência de TVP em pacientes com Lesão Medular, tanto aguda quanto crônica (após um ano da lesão). A investigação de trombofilia deve ter como base os fatores clínicos, fatores de risco para TVP e história familiar de trombose / Objective: Evaluate the impact of risk factors in the development of thromboembolic events in patients with spinal cord injury. Design: Observational, prospective and cross study. Eligible patients (n=100) had spinal injury (SI) by spinal cord injury (SCI), older than 18 years of age. The degree of motor and sensory lesion was evaluated based on ASIA Impairment Scale (AIS). Blood samples were collected for coagulation exams, hemogram, laboratory and biochemical analyses. Ultrasonography analyzes were performed from deep and superficial venous systems of lower limbs. Quantitative real-time PCR experiments were performed in order to investigate mutations in the prothrombin (G20210A) and Leiden factor V (G1691A) genes. Results: The main finding of this study was the higher occurrence of Deep Venous Thromboembolism (DVT) in patients with Leiden factor V and hyper homocysteinemia. There was no association between SI for DVT, venous thromboembolism (VT) and thrombophilia. Also, there was no relation between lupus anticoagulant and anti-cardiolipin. Conclusions: There is an important difference in the incidence of DVT in patients with SI by acute SCI and after 1 year. The conduct of the investigation for thrombophilia should be based on clinical factors, risk factors for DVT and family history of thrombosis