Filomena Cappucci

Gain of function gene mutations and venous thromboembolism: Distinct roles in different clinical settings

Objective: To calculate the prevalence of common gain of function gene mutations in patients with different clinical manifestations of venous thromboembolism. Design and setting: Case–control study in two hospitals in Italy. Participants: 387 patients with venous thromboembolism and 286 controls. Main measures: Factor V (FV) Leiden, factor II (FII) A20210 and JAK2 V617F mutations. Results: Among patients with deep vein thrombosis in one leg, 23 (20.9%) carried FV Leiden and FII A20210 mutations. Similar figures were observed in patients with cerebral vein thrombosis (CVT; n = 9; 20.0%) and in patients presenting with splanchnic vein thrombosis (SVT; n = 26; 18.7%). A lower prevalence was obtained in patients with retinal vein thrombosis (n = 11; 11.8%). The JAK2 F617 mutant allele was found in 27 (21.1%) patients with SVT, but in none of the patients presenting with a thrombotic event from different districts. 13 of the 27 JAK2 V617F-positive subjects with SVT were previously known to have a myeloproliferative disease (MPD). Three other patients had a diagnosis of MPD after the occurrence of the thrombotic event. Conclusion: Carriership of FV Leiden or FII A20210 mutations identifies an at-risk condition for venous thrombosis in the lower extremities, SVT or CVT. In patients with SVT, screening for the JAK2 V617F mutation may be useful in recognising patients who should be carefully observed for the subsequent development of overt MPD. Thus, genetic tests may play a different role, various clinical manifestations of venous thromboembolism being associated with distinct risk profiles.

Low protein Z levels and risk of occurrence of deep vein thrombosis.

Summary.  Background: Protein Z (PZ) serves as a cofactor for activated factor X inhibition by the PZ‐dependent protease inhibitor. In vivo and in vitro studies aimed at investigating the role of PZ levels in venous thombosis have produced conflicting results. Objectives: We investigated whether reduced PZ levels and PZ gene common variants are associated deep vein thrombosis (DVT). Patients and methods: In 197 patients with DVT and in 197 age‐matched and sex‐matched controls, PZ plasma levels and gene polymorphisms were evaluated by means of an enzyme‐linked immunosorbent assay and direct cycle sequence analysis. Results: Similar PZ levels were found in controls (1.44; SD 0.63 μg mL−1) and in patients (1.44; SD 0.96 μg mL−1). The incidence of PZ levels below the 5.0 (0.52 μg mL−1) or the 2.5 percentile of controls (0.47 μg mL−1) was higher in patients (10.2% and 8.7%, respectively) than in controls {4.1% [odds ratio (OR) 2.7, 95% confidence interval (CI) 1.2–7.3], and 2.0% (OR 4.6, 95% CI 1.5–13.9), respectively}. This relationship was independent of the effect of age, sex, and factor V Leiden and FII A20210 alleles [OR 2.8 (95% CI 1.1–7.3), and OR 4.9 (95% CI 1.4–17.3)]. PZ levels were associated with the intron C G‐42A and the intron F G79A polymorphisms in cases (r2 = 0.129) and in controls (r2 = 0.140). However, frequencies of the PZ gene polymorphisms were similar in the two groups and were not associated with very low PZ levels. Conclusions: The present data suggest an association between very low PZ plasma levels and the occurrence of DVT, with PZ gene polymorphisms contributing little to this relationship.

Symptomatic Venous Thromboembolism and Thrombophilic Status in Adult Acute Leukemia: A Single-Center Experience of 114 Patients at Diagnosis

Inherited and acquired thrombophilia are associated with venous thromboembolic events (TE). The prevalence of inherited and acquired prothrombotic risk factors and the incidence of symptomatic TE were evaluated in a cohort of 114 adult acute leukemia patients. The most frequent prothrombotic risk factor was hyperhomocysteinemia which occurred in 46.6% of patients. The incidence of TE was 9.6%, mainly in the first month of follow-up. In multivariate analysis, hyperhomocysteinemia was the only risk factor for TE (OR 33.90; 95% CI 1.53–751.33; p = 0.026). The results of this study indicate that measurements of homocysteinemia could be useful in determining the risk of early TE in adult acute leukemia patients, while systematic thrombophilia screening should not be justified.

Antithrombotic prophylaxis during pregnancy in women with deficiency of natural anticoagulants.

Prevalence of obstetric complications in women with deficiency of natural anticoagulants is difficult, because these defects are very rare in general population. Furthermore, the available data on prophylactic intervention in such individuals to decrease the obstetric risk are also very limited. To evaluate in a setting of women with rare hereditary thrombophilias, deficiency of antithrombin, protein C or protein S whether thromboprophylaxis during pregnancy could affect foeto-maternal outcome. Retrospective cohort study in two Italian thrombosis centres: 32 women with an established hereditary deficiency of natural anticoagulants antithrombin, protein C or protein S were enrolled because of a history of unexplained foetal losses with or without venous thromboembolism. Overall, information on the management of 103 pregnancies was obtained and the outcome in the absence or in the presence of enoxaparin treatment was recorded. Live births were recorded in 18 women (56.2%). Ten women had early foetal losses, 16 intrauterine foetal death and six both. Eight pregnancies were treated with enoxaparin. Seven out of eight treated pregnancies [87.5%, 95% confidence interval (CI) 52.9–97.7] and 27 out of 95 not-treated pregnancies (28.4%, 95% CI 20.3–38.1) resulted in the delivery of a live newborn (Fisher exact test: P = 0.002), with a risk of foetal loss in untreated pregnancies 3.1 times (95% CI 1.7–3.5) higher than in treated ones. In this setting of patients with rare causes of thrombophilia, antithrombotic prophylaxis during pregnancy improves foeto-maternal outcome.

Inherited abnormalities of fibrinogen: 10-year clinical experience of an Italian group.

Inherited abnormalities of fibrinogen present a high variability in penetrance and expressivity, and clinical manifestations vary from severe bleeding or thrombosis to asymptomatic This variability makes clinical and genetic counseling more difficult. We report the experience of a clinical group working in specialist centers in Southern Italy on a series of consecutive patients presenting with congenital abnormalities of fibrinogen. Over 10 years, 18 patients were diagnosed to carry a congenital abnormality of fibrinogen. These patients and 26 first-degree relatives were investigated in-depth to fully characterize the nature of their abnormal fibrinogen levels. A gene mutation was identified in 15 patients (four afibrinogenemic patients, three hypofibrinogenemic patients, and eight dysfibrinogenemic patients). A new mutation was found in four of them: Aα Arg159Stop in one afibrinogenemic patient, Aα Arg104Cys in two hypofibrinogenemic patients, and Aα Pro270Thr in one dysfibrinogenemic patient. While all afibrinogenemic patients had clinically important bleeding, participants presenting with hypofibrinogenemia remained asymptomatic. In the presence of the synthesis of an abnormal molecule, the clinical phenotype was not strictly related to plasma fibrinogen levels but was associated with the molecular defect, most carriers remaining asymptomatic. Personal and family histories of bleeding and thrombosis are important for the clinical management of patients presenting with congenital abnormalities of fibrinogen. Biochemical and genetic investigations may be a useful guide for decision-making, providing additional steps in the assessment of the risk of patients presenting with low levels of a normal molecule (hypofibrinogenemia and afibrinogenemia) and with an abnormal molecule (dysfibrinogenemia), respectively.

Impact of common thrombophilias and JAK2 V617F on pregnancy outcomes in unselected Italian women.

Summary.  Background: Although an association between thrombophilias and adverse pregnancy outcome has been shown, the influence of the most common inherited thrombophilias and the somatic mutation JAK2 V617F in determining an adverse outcome is questioned. Objectives: We examined the contribution of the factor V Leiden (FVL), the prothrombin G20210A (PTm) and the somatic JAK2 V617F mutations to adverse pregnancy outcome in an unselected cohort of pregnant women. Patients/methods: During the study period, 5345 pregnant women were admitted to the 14 hospitals of the five provinces of the Campania region (Italy). Of these, 3097 samples were investigated and obstetric history collected. The presence of the FVL, PTm, and JAK2 V617F mutation was prospectively determined by polymerase chain reaction followed by TaqMan SNP genotyping assays. Results and conclusions: We identified 119 (3.8%) women that carried FVL and 138 (4.4%) with the PTm. Only 4 (0.1%) women carried both mutations. Only one woman tested positive for the JAK2 V617F somatic mutation. The prevalence of a previous history of an adverse pregnancy outcome was similar in women with common thrombophilias as compared to those without. In the current pregnancy, there was no association of any of the genetic markers considered with any of the adverse outcomes investigated. Carriership of FVL or PTm showed a positive trend with delivery of a small for gestational age newborn (OR: 1.5, 95% CI: 0.9–2.5). Pregnancy outcomes in asymptomatic women with inherited thrombophilias are often uneventful. Therefore, in women at low‐risk of an adverse pregnancy, neither screening for common thrombophilias nor administration of routine thromboprophylaxis are warranted.

An unreported mutation within protein Z gene is associated with very low protein levels in women with fetal loss

Gene variant intron C G-42A of protein Z is significantly associated with the occurrence of fetal loss. A previously unreported sporadic missense mutation within exon 8 is described in a patient with very low protein Z levels.

Protein Z g-42a variant and the risk of pregnancy-related venous thromboembolism in a cohort of Italian patients

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Pharmacogenetics of dabigatran etexilate interindividual variability.

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Clinical histories and molecular characterization of two afibrinogenemic patients: Insights into clinical management

INTRODUCTION Dabigatran etexilate is given in fixed doses without coagulation monitoring for the prevention of blood clots in at risk adults. A high inter-individual variability in blood concentrations of the active metabolite of dabigatran has been reported. ABCB1 and CES1 exert an important effect in the metabolism of dabigatran etexilate and allele variants at these two loci are likely to play a pivotal role. To investigate whether screening for polymorphisms within the ABCB1 and the CES1 genes would explain a portion of the inter-individual variability in blood concentrations of the active metabolite of dabigatran. MATERIAL AND METHODS In a cohort of patients who had atrial fibrillation and on anticoagulant prophylaxis with dabigatran etexilate, we investigated whether genotypes at rs4148738 (ABCB1), rs8192935 (CES1), and rs2244613 (CES1) loci would affect plasma dabigatran trough and peak concentrations. RESULTS AND DISCUSSION Among 92 patients (median age: 72.0years, range: 52-92) analyzed, no clinical variable or genotype was associated with a significant difference in dabigatran peak concentrations. As for trough concentrations, in addition to creatinine clearance, and sex a significant association with the CES1 SNP rs8192935 (p=0.023) was detected. The mean adjusted plasma levels were higher among patients with the CC genotype (86.3ng/dl) than in those carrying the T allele (62.1ng/dl). No significant effect was found for the ABCB1 SNP rs4148738. The CES1 SNP rs8192935 significantly influenced the dabigatran trough concentrations and carriers of the T allele showed significantly lower concentrations than did carriers of the CC genotype.