scholarly journals How I Manage Thrombotic/Thromboembolic Complications in Myeloproliferative Neoplasms

2020 ◽  
Vol 40 (01) ◽  
pp. 047-053
Author(s):  
Steffen Koschmieder

AbstractPatients with myeloproliferative neoplasms (MPNs), such as polycythemia vera, essential thrombocythemia, and primary myelofibrosis, are at increased risk for arterial and venous thrombosis/thromboembolism. In particular, the risk of splanchnic venous thrombosis, such as portal vein thrombosis or Budd–Chiari syndrome, is significantly higher in patients with MPN than in the normal population. At the same time, MPN patients are at increased risk for severe bleeding. Therefore, the treatment of patients with MPN must be based on their suspected probability of thrombosis/thromboembolism and bleeding. For this purpose, patient and MPN-specific risk factors are used. Patients at expected high risk of thrombosis should receive adequate primary or secondary thromboprophylaxis in addition to cytoreductive therapy. This may consist of antiplatelet agents and/or anticoagulant agents and must be balanced with the individual bleeding risk. The goal is to increase the quality of life and life span of patients with MPNs by preventing (re-)thrombosis and severe bleeding.

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 3163-3163 ◽  
Author(s):  
Lisa Pieri ◽  
Paola Guglielmelli ◽  
Massimo Primignani ◽  
Silvia Betti ◽  
Maria Luigia Randi ◽  
...  

Abstract Philadelphia-negative Myeloproliferative Neoplasms (MPN), including Polycythemia Vera (PV), Essential Thrombocythemia (ET), Myelofibrosis (Primary [PMF] and secondary to PV and ET [PPV-, PET-MF] and unclassified MPN (U-MPN), are associated with an increased risk of venous thrombosis in unusual sites, such as splanchnic vessels (SVT). SVT can lead to complications such as portal hypertension, esophageal and gastric varices, ascites,hepatic failure and biliopathy. According to a meta-analysis MPN is the underlying cause of portal vein thrombosis (PVT) in 31.5% and Budd Chiari syndrome (BCS) in 40.9% of cases (Smalberg, 2012); a more in-depth analysis of clinical characteristics and evolution of MPN-associated SVT has been hampered by heterogeneity of cohorts comprising small number of cases. We conducted a retrospective multicenter study in patients (pts) with SVT associated with WHO2008-diagnosed MPN, with the aim to describe patient characteristics, disease course and prognostic factors with potential implications for clinical practice. Data were collected from 16 international hematologic centers in the framework of the Italian AGIMM and the IWG-MRT groups. We collected 519 cases of pts with PVT, splenic or mesenteric vein thrombosis (75.1%) and BCS (24.9%) associated with MPN. We used as comparator a cohort of 1686 controls (Ctr) represented by MPN without (w/o) SVT: 741 ET (43.9%), 684 PV (39.7%), 261 PMF (15.5%). Frequency of MPN associated with SVT was 37.8% ET (n=196), 36.8% PV (n=191), 15.4% MF (n=80), 10% U-MPN (n=52). Median follow-up was 89.9 months (mo) (range 0.5-430). For SVT vs Ctr group females were 54.5% vs 44.4% in PV (P=0.001), 68.4 vs 63.5% (p=0.13) in ET, 63.7% vs 29.1% in PMF (p<0.0001); median age at MPN diagnosis (dg) was 43.5 yr (range 12-90) vs 60.6 yr (range 12-93) (p<0.0001). Age at SVT dg was 44 yr (range 15-85). In 240 cases (46.7%) MPN and SVT dg were coincident, in 121 (23.6%) SVT occurred before MPN dg (median 26 mo, range 4-307) and in 153 (29.8%) during MPN follow up (median 68 mo, range 4-362). JAK2V617F mutation was found in 94% PV vs 94% in Ctr, 84% vs 61% ET (p<0.0001), 88.1% vs 68% PMF (p=0.006) and in 93% U-MPN. Erythropoietin-independent colonies (EEC) were evaluated in 111 SVT pts and found in 80 (72%), accounting for 38/48 PV (79%), 31/44 ET (70.5%), 9/12 PMF (75%) and 2/7 U-MPN (28.6%). At dg, SVT PV pts had lower hemoglobin levels than Ctr: median was 17.4 g/dL vs 18.5 g/dL (p<0.0001) in male, 16.9 g/dL vs 17.7 g/dL (p=0.0006) in female. A co-existing thrombophilic status was found in 38.5% SVT vs 11.8% of Ctr (p<0.0001). Recurrent SVT occurred in 12.2% of pts with a rate of 1.6% person/year (CI 1.2-2.1); risk of venous thrombosis other than SVT was increased in SVT group vs Ctr (p=0.02), with no difference for arterial thrombosis. Hemorrhage was more frequent in SVT group (32%) vs Ctr (7.2%)(p<0.0001), mainly related to esophageal varices, which were present in 66.9% of SVT pts. There was no difference in evolution to MF and acute leukemia (AL) for PV and ET pts with and w/o SVT, while risk of AL was lower in MF with SVT (p<0.00001). Overall survival was shorter in ET pts with SVT vs Ctr (p<0.0001). In PMF survival was better in SVT group (p<0.00001) and was associated with a higher proportion of SVT pts in lowest risk categories: IPSS low 65%, intermediate-1 20%, intermediate-2 10% and high 5% compared with 15%, 34%, 25% and 26% in Ctr group. At last FU, 79/519 pts (15.2%) had died; causes of death were evolution to AL (15.4%), other cancers (13.8%), disease progression without AL (10.8%), SVT (10.8%), hepatic failure and venous thrombosis other than SVT (7.7% each), heart failure and arterial thrombosis (6.2% each), hemorrhage (5.5%), renal failure and infection (4.6% each). Therapy after SVT included anticoagulation in 77%, antiaggregant in 21.2% and combination in 1.8%; 70% received cytotoxic drugs; 12.4% were treated with transjugular porto-systemic shunt. Beta blocker therapy was used in 48.5% of pts and correlated with improved survival (p=0.041) MPN associated with SVT correlated with younger age and female sex and might antedate the clinical phenotype in a quarter of the patients. MPN-associated SVT equally affected PV and ET, was more likely to occur in the presence of JAK2V617F or underlying thrombophilia and predicted recurrent venous but not arterial thrombosis. The apparent association of SVT with better or worse prognosis in PMF and ET, respectively, requires further investigation. Disclosures No relevant conflicts of interest to declare.


Cancers ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 3132
Author(s):  
Parvis Sadjadian ◽  
Kai Wille ◽  
Martin Griesshammer

Ruxolitinib (RUX), a JAK1/JAK2 inhibitor, is approved for second-line therapy in patients with polycythemia vera (PV) who are resistant or intolerant to hydroxyurea. Due to the immunomodulatory and immunosuppressive effect of RUX, there is an increased susceptibility to infections. However, an increased risk of infection is inherent to even untreated myeloproliferative neoplasms (MPN). To obtain more information on the clinical significance of RUX-associated infections in PV, we reviewed the available literature. There is no evidence-based approach to managing infection risks. Most data on RUX-associated infections are available for MF. In all studies, the infection rates in the RUX and control groups were fairly similar, with the exception of infections with the varicella zoster virus (VZV). However, individual cases of bilateral toxoplasmosis retinitis, disseminated molluscum contagiosum, or a mycobacterium tuberculosis infection or a hepatitis B reactivation are reported. A careful assessment of the risk of infection for PV patients is required at the initial presentation and before the start of RUX. Screening for hepatitis B is recommended in all patients. The risk of RUX-associated infections is lower with PV than with MF, but compared to a normal population there is an increased risk of VZV infection. However, primary VZV prophylaxis for PV patients is not recommended, while secondary prophylaxis can be considered individually. As early treatment is most effective for VZV, patients should be properly informed and trained to seek medical advice immediately if cutaneous signs of VZV develop. Vaccination against influenza, herpes zoster, and pneumococci should be considered in all PV patients at risk of infection, especially if RUX treatment is planned. Current recommendations do not support adjusting or discontinuing JAK inhibition in MPN patients to reduce the risk of COVID-19.


2008 ◽  
Vol 100 (12) ◽  
pp. 1076-1083 ◽  
Author(s):  
Olaf H. Klungel ◽  
Patrick C. Souverein ◽  
Anthonius de Boer ◽  
Tom Schalekamp

SummaryTreatment with vitamin K antagonists (coumarins) is associated with an increased risk of bleeding. In order to elucidate the bleeding risk of users of antiplatelet drugs among users of coumarins, we assessed the odds ratio of major bleeding associated with use of antiplatelet drugs in users of the coumarins acenocoumarol and phenprocoumon. We used data froma Dutch record linkage system, including pharmacy and linked hospitalization records for approximately two million subjects, to conduct a nested case control study in a cohort of new users of coumarins. Cases were patients who were hospitalized with a primary diagnosis of major bleeding while taking coumarin and were matched with up to four control subjects. Conditional logistic regression analysis was used to determine ORs and 95% confidence intervals (CI).We identified 1848 case patients who were matched to 5818 controls. Users of clopidogrel or aspirin showed a significantly increased risk of hospitalization because of major bleeding (OR 2.9, 95% CI 1.2–6.9 and OR 1.6, 95% CI 1.3–1.9, respectively), whereas users of dipyridamole and combinations of antiplatelet drugs showed a strong trend (OR 1.5, 95% CI 1.0–2.3 and OR 1.8, 95 % CI 1.0–3.3, respectively). In all cases, the risks were greater for upper gastrointestinal bleedings than for other bleedings. In conclusion, the use of any antiplatelet drug increases the risk of hospitalization for major bleeding among users of coumarins. Concurrent use of clopidogrel or dipyridamole and coumarins is probably not safer than concurrent use of aspirin and coumarins.


2015 ◽  
Vol 29 (3) ◽  
pp. 239-249 ◽  
Author(s):  
David S. Roffman

A review of the literature was conducted for clinical trials evaluating the antiplatelet P2Y12 receptor antagonists, clopidogrel, prasugrel, and ticagrelor, as well as the guidelines for the management of acute coronary syndrome (ACS) or myocardial infarction. Clinical guidelines recommend that patients with ACS be treated with dual oral antiplatelet therapy of aspirin plus clopidogrel, prasugrel, or ticagrelor. The selection of an appropriate antiplatelet agent depends on the treatment approach and a patient’s bleeding risk and clinical history. With respect to antiplatelet activity, prasugrel and ticagrelor demonstrate greater potency and less interpatient variability than clopidogrel. In phase III clinical trials, prasugrel and ticagrelor reduced the incidence of ischemic events in patients with ACS compared with clopidogrel. Ticagrelor and clopidogrel were associated with a similar risk of major bleeding, whereas patients receiving prasugrel had an increased risk of major bleeding versus those receiving clopidogrel. Pharmacists can provide guidance on the appropriate use of antiplatelet agents as well as the use of concomitant medications, while being vigilant for any potential drug interactions.


2019 ◽  
Vol 6 (2) ◽  
pp. 10-17
Author(s):  
Eugenia Biguzzi ◽  
Karin van Galen ◽  
Rezan A Kadir

Abstract Haemophilia is an X-linked inherited disorder that affects males and females, though the bleeding risk in girls and women has traditionally been under-recognised. About one third of haemophilia cases occur in individuals where there is no known family history. The gene mutations for rare bleeding disorders are not carried on the X chromosome and are therefore not sex-linked; however, the risk of passing on the condition is greatly increased for consanguineous parents where both parents may carry a copy of the fault in the genetic code which causes the condition. Genetic testing should be offered to every prospective mother, ideally before conception. This should be supported by counselling as the implications for family planning are profound. Von Willebrand factor (VWF) has an important role in primary and secondary haemostasis. Loss of function or low levels of VWF are associated with spontaneous bleeding causing nosebleeds, heavy periods and bruising as well as jpost-surgical bleeding. Joint bleeding and intracranial haemorrhage can also occur in those with a severe type of VWF. Diagnosis depends on bleeding assessment, family history and measurement of VWF. There are three types of VWD: Types 1 and 3 are caused by low or absent levels of VWD; Type 2 is caused by loss of function. Of these, Type 3 VWD is associated with the most severe bleeding risk but there is wide variation in bleeding phenotype among the other sub-types. The correlation between genetic mutation and bleeding phenotype is weak in VWD; therefore genetic testing is mainly useful for interpreting the risk when planning a family and to allow prenatal diagnosis in severe bleeding disorders. Genetic testing is essential for prospective parents to make fully informed decisions about having a family and how or whether to proceed with a pregnancy. The rationale for prenatal testing is to determine the bleeding status of the foetus and to inform decisions about managing delivery. Women may choose to terminate a pregnancy to avoid having a child with severe haemophilia. For some couples the option of adoption or not having children may be explored. Options for prenatal diagnostic testing include non-invasive methods, e.g. assessment of free foetal DNA in maternal plasma to determine the sex of a baby from 10 weeks in pregnancy, and invasive methods, e.g. chorionic villus sampling or amniocentesis, to determine the inheritance of the genetic mutation. Invasive methods are associated with a very small increased risk of pregnancy loss or early labour, which many couples feel is an unacceptable risk. Advanced techniques such as preimplantation screening also available, but require a huge commitment as this involves an IVF technique.


Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 3148-3148
Author(s):  
Elizabeth Kander ◽  
Qiuhong Zhao ◽  
Tracy Wiczer ◽  
John C. Byrd ◽  
Jennifer A. Woyach ◽  
...  

Abstract BACKGROUND: Ibrutinib is an irreversible inhibitor of BTK in the B-cell receptor signaling cascade and is widely used to treat chronic lymphocytic leukemia (CLL) and other B-cell malignancies. Ibrutinib also inhibits the tyrosine kinase Tec in platelets, which may be one of the mechanisms of its bleeding toxicity. This makes concomitant use of anticoagulation (AC) or antiplatelet agents challenging, which is a common delimma as many patients taking ibrutinib are elderly and have increased risks of venous and arterial thromboses. The incidence of thrombosis in patients taking ibrutinib is unknown, and we hypothesized that the risk of thrombosis may be reduced during ibrutinib treatment. Therefore, we conducted a single-institution retrospective cohort study to determine the incidence and type of both arterial and venous thromboses during ibrutinib treatment and their management. METHODS: We reviewed medical records of all patients treated with ibrutinib for a hematological malignancy at the Ohio State University between 6/1/2010 and 3/31/2016. Baseline patient and disease characteristics were captured at time of starting ibrutinib. All thrombotic events occurring at any time during treatment with ibrutinib and within three days of its discontinuation were recorded. Time to thrombosis was calculated from the date of starting ibrutinib to the date of thrombosis or censored at the last assessment date, treating discontinuation of ibrutinib or death prior to thrombosis as competing risks. The cumulative incidence of thrombosis was estimated and the Fine and Gray regression models accounting for competing riskes were used to examine the association between patient characteristics and risk of thrombosis. RESULTS: The cohort included 565 patients. Median age was 65 (range 23->89) years and 70.3% (397/565) were men. The majority of patients had CLL (73.6%, 416/565). Other diagnoses included mantle cell lymphoma (9.9%, 56/565), indolent B-cell malignancies (8.1%, 46/565), and aggressive lymphomas (8.3%, 47/565). Median number of prior treatments was 3 (range 0-18) and 6.5% (37/565) of patients were treatment naïve. Prior to ibrutinib, 144 of 565 patients (25.5%) had a history of thrombosis. Sixty-four (11.3%, 64/565) patients had only venous thromboses, 66 (11.7% 66/565) had only arterial thromboses, and 14 patients had both. Concurrently with ibrutinib, 193 (34.2%) patients received antiplatelet agents, 16 (2.8%) patients received AC, and 31 (5.5%) patients received both. Total ibrutinib exposure for the cohort was 1,429 person-years with a median exposure of 2.39 (range 0-7.36) years per patient. A second antineoplastic agent was given with ibrutinib in 30.8% (174/565) of cases, including an immunomodulatory drug in 24 (4.2%, 24/565) patients. During ibrutinib treatment, 22 of 565 (3.9%) patients experienced 24 acute thrombotic events, mostly arterial (Table 1). The incidence of thrombosis was 1.7 (95% CI 1.1-2.5) per 100 person-years of ibrutinib exposure. Of the venous thromboses, 87.5% (7/8) were deep vein thromboses and developed at a median of 7.5 (range 0.5-75.3) months after starting ibrutinib. Of the arterial thromboses, the majority were acute cerebrovascular accidents (37.5%, 6/16) and developed at a median of 27.4 (range 0.4 - 56.6) months after starting ibrutinib. Thrombosis treatment is summarized in Table 1. After thrombosis, ibrutinib was discontinued or held in the majority of cases (75%, 18/24). One patient developed a recurrent thrombosis while on ibrutinib and AC. There were six bleeding events, 3 major (based on ISTH criteria) and 3 minor: all were taking ibrutinib and most were on AC (2 patients on antiplatelet, 1 on AC, 2 on both, 1 on neither). On univariable analysis, the only factors associated with significant (p<0.05) and substantial (HR >2) increased risk of venous thrombosis were prior venous (HR 4.73, CI: 1.06-21.11) and arterial (HR 15.66, CI: 3.07-79.87) thromboses. Antiplatelet use was not significantly associated with either thrombus type. CONCLUSIONS: The cumulative incidence of thrombosis during ibrutinib treatment was low (1.7 per 100 person-years), with the majority being arterial. Prior thrombosis was associated with increased venous thrombosis risk. There are more bleeding than thrombotic complications after patients develop thromboses on ibrutinib, and optimal treatment strategies for this population requires further investigation. Disclosures Kander: AstraZeneca: Consultancy. Wang:Daiichi Sankyo: Consultancy, Other: Travel.


Blood ◽  
2021 ◽  
Vol 138 (Supplement 1) ◽  
pp. 4258-4258
Author(s):  
Maged Al-Ammari ◽  
Abdul Ali Peer Zada ◽  
Ibraheem H. Motabi ◽  
Belal M. Albtoosh ◽  
Syed Y. Altaf ◽  
...  

Abstract Background: JAK2 GGCC 46/1 haplotype can be represented by four main SNPs (rs3780367, rs10974944, rs12343867, and rs1159782) which replace one cytosine and three thymidines by two guanosines and two cytosines, generating a "GGCC" combination. These four SNPs located on JAK2 introns 10, 12, 14, and 15, respectively, and are always inherited together, being in complete linkage disequilibrium. The 46/1 component of the name came from Jones et al. study where the haplotype structure of the JAK2 gene was mapped using 14 SNPs genotyped by the Wellcome Trust Case Control Consortium (WTCCC) in 1500 healthy blood donors. Two haplotypes (numbers 46 and 1) were found to be identical except for one SNP, and they have a combined frequency of 0.24 in healthy individuals. Numerous observational studies associate this haplotype with myeloproliferative neoplasms (MPNs), as well as splanchnic vein thrombosis (SVT) and non-splanchnic vein thrombosis (non-SVT). In contrast to 24% frequency noted in healthy population, the frequency goes up to 40-80% in JAK2 V617F mutated MPN, and in 64% of those with JAK2 exon 12 mutations (Anelli et al. IJMS, 2018). We herein report our study of JAK2 GGCC (46/1) Haplotype in unprovoked Venous Thrombotic Events (VTE) in patients with negative thrombophilia workup, including negative JAK2 V617F mutation. Methods: We retrospectively identified patients positive for one of the two SNPs (rs12343867 and rs10974900) and unprovoked venous thrombotic among adult patients with negative thrombophilia workup (including JAK2 mutation) treated at tertiary care center from January 2018 to January 2021. Results: We have identified 8 patients, Table (1), that were positive for JAK2 46/1 haplotype SNPs, of whom 62.5% were homozygous 2/2, 25% heterozygous 1/2, while only 12.5% harbor homozygous 1/1 (a normal variant of JAK2 haplotype). The median age 48.5 years (23-65), and the majority (87.5%) were females. Thrombosis site was noted to be SVT in half of the patients, while non-SVT was noted in the other half (12.5% had cerebral vein thrombosis, 12.5% had deep venous thrombosis, 12.5% had a pulmonary embolism, and 12.5% had jugular vein thrombosis). Half of the patients had more than one site venous thrombosis and the other half had only one site. Around 37.50% of the patients had recurrent venous thrombosis on top of therapeutic anticoagulation. Two patients (25%) had high hemoglobin (17.4/16.7) g/dl, but did not fulfill the criteria for polycythemia vera diagnosis (of whom one is a male smoker and one was a female). None of the patients had leukocytosis or thrombocytosis. By imaging, one patient had mild splenomegaly which could be related to SVT. Conclusion: We report on a potential correlation between unprovoked thrombotic events, mainly venous thrombotic events, with JAK2 46/1 haplotype in patients with a negative thrombophilia workup, a finding that merit further investigation. Figure 1 Figure 1. Disclosures No relevant conflicts of interest to declare.


2015 ◽  
Vol 6 (03) ◽  
pp. 407-409 ◽  
Author(s):  
Josef Finsterer ◽  
Ernst Sehnal

ABSTRACTRecent data indicate that in patients with hereditary hemorrhagic teleangiectasia (HHT), low iron levels due to inadequate replacement after hemorrhagic iron losses are associated with elevated factor-VIII plasma levels and consecutively increased risk of venous thrombo-embolism. Here, we report a patient with HHT, low iron levels, elevated factor-VIII, and recurrent venous thrombo-embolism. A 64-year-old multimorbid Serbian gipsy was diagnosed with HHT at age 62 years. He had a history of recurrent epistaxis, teleangiectasias on the lips, renal and pulmonary arterio-venous malformations, and a family history positive for HHT. He had experienced recurrent venous thrombosis (mesenteric vein thrombosis, portal venous thrombosis, deep venous thrombosis), insufficiently treated with phenprocoumon during 16 months and gastro-intestinal bleeding. Blood tests revealed sideropenia and elevated plasma levels of coagulation factor-VIII. His history was positive for diabetes, arterial hypertension, hyperlipidemia, smoking, cerebral abscess, recurrent ischemic stroke, recurrent ileus, peripheral arterial occluding disease, polyneuropathy, mild renal insufficiency, and epilepsy. Following recent findings, hypercoagulability was attributed to the sideropenia-induced elevation of coagulation factor-VIII. In conclusion, HHT may be associated with hypercoagulability due to elevated factor-VIII associated with low serum iron levels from recurrent bleeding. Iron substitution may prevent HHT patients from hypercoagulability.


2020 ◽  
pp. 1-8
Author(s):  
Odit Gutwein ◽  
Noa Lavi ◽  
Merav Barzilai ◽  
Adi Shacham-Abulafia ◽  
Avi Leader ◽  
...  

The BCR-ABL-negative myeloproliferative neoplasms (MPN) are associated with high incidence of venous thrombosis and a significant rate of recurrent events, but there is no consensus regarding their management. In this retrospective study, we analyzed 96 patients with MPN-related venous thrombosis. The index venous thrombosis occurred at a median age of 58 years (IQR 37–71), with 58% of the events involving unusual sites. Patients who were on antiplatelet agents at the time of index thrombosis tended to be older than patients who were not receiving antiplatelets at the time of index thrombosis. The majority of index thromboses occurring after the diagnosis of MPN had uncontrolled blood counts at the time of event and were not receiving antithrombotic agents. Following the thrombotic episode, 75% of patients received long-term anticoagulation. At a median follow-up of 3.4 years, the recurrence rate was 14%. Thrombophilia was significantly more prevalent among patients with recurrent thrombosis compared to patients without recurrence (<i>p</i> &#x3c; 0.01). Patients who developed a recurrent event early were more likely to have thrombophilia (either inherited or antiphospholipid antibodies), and controlled blood counts, and were likely to receive anticoagulation at the time of recurrence compared to patients with later recurrences. Thrombophilia may contribute to venous thrombosis recurrence, especially early after the index venous thrombosis. Suboptimal anticoagulation and blood count control are factors associated with late venous thrombosis recurrence.


2001 ◽  
Vol 86 (09) ◽  
pp. 804-808 ◽  
Author(s):  
Alberto Tosetto ◽  
Monica Simioni ◽  
Marco Ruggeri ◽  
Domenico Madeo ◽  
Francesco Rodeghiero ◽  
...  

SummaryWe hypothesized that increased prothrombin levels associated with G20210A prothrombin gene mutation could affect the results of activated protein C (APC) resistance phenotype and increase the risk of venous thrombosis (VT). The increasing addition of purified prothrombin in plasma of 90 normal subjects resulted in a parallel significant increase of APC resistance. Significantly different mean n-APC-SR in 879 GG20210 subjects compared to 27 heterozygous carriers of isolated G20210A mutation was observed (1.0 ± 0.12 vs. 0.95 ± 0.11; P = 0.02) in a random sample of 906 normal population subjects. Twenty-seven families with VT and isolated G20210A mutation consecutively diagnosed during 1998-1999 were evaluated. Mean n-APC-SR was significantly lower in the 80 G20210A carriers compared to 58 GG 20210 relatives investigated, even after sex and age adjustment (0.92 ± 0.08 vs. 1.05 ± 0.13; P < 0.0001). A strong relationship between plasma prothrombin level and n-APC-SR was observed in the families. When n-APC-SR values were grouped in tertiles, the odds ratio for VTE, after exclusion of the index cases and adjustment for 20210 status, for subjects in the lowest tertile (n-APC-SR 0.73-0.90) was 4.58 (95% CI 0.78-26.88) compared to upper tertile (n-APC-SR 1.01-1.30). In conclusion, in subjects with G20210A mutation APC resistance is significantly increased, correlates with plasma prothrombin level and the carriers with the lowest APC resistance values have an increased risk of VTE.


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