Muriel Giansily-Blaizot

Analysis of the genotypes and phenotypes of 37 unrelated patients with inherited factor VII deficiency

Severe inherited factor VII (FVII) deficiency is a rare autosomal recessive disorder with a poor relationship between FVII coagulant activity and bleeding tendency. Both clinical expression and mutational spectrum are highly variable. We have screened for mutations the FVII gene of 37 unrelated patients with a FVII coagulant activity less than 5% of normal pooled plasmas. The nine exons with boundaries and the 5′ flanking region of the FVII gene were explored using a combination of denaturing gradient gel electrophoresis and direct DNA sequencing. This strategy allowed us to characterise 68 out of the 74 predicted FVII mutated alleles. They corresponded to a large panel of 40 different mutations. Among these, 18 were not already reported. Genotypes of the severely affected patients comprised, on both alleles, deleterious mutations which appeared to be related to a total absence of activated FVII. We suggest that this absence of functional FVII can explain the severe clinical expression. Whether a small release of FVII is sufficient to initiate the coagulation cascade and to prevent the expression of a severe phenotype, requires further investigations.

Prophylaxis in congenital factor VII deficiency: indications, efficacy and safety. Results from the Seven Treatment Evaluation Registry (STER)

Because of the very short half-life of factor VII, prophylaxis in factor VII deficiency is considered a difficult endeavor. The clinical efficacy and safety of prophylactic regimens, and indications for their use, were evaluated in factor VII-deficient patients in the Seven Treatment Evaluation Registry. Prophylaxis data (38 courses) were analyzed from 34 patients with severe factor VII deficiency (<1-45 years of age, 21 female). Severest phenotypes (central nervous system, gastrointestinal, joint bleeding episodes) were highly prevalent. Twenty-one patients received recombinant activated factor VII (24 courses), four received plasma-derived factor VII, and ten received freshfrozen plasma. Prophylactic schedules clustered into “frequent” courses (three times weekly, n=23) and “infrequent” courses (≤2 times weekly, n=15). Excluding courses for menorrhagia, “frequent” and “infrequent” courses produced 18/23 (78%) and 5/12 (41%) “excellent” outcomes, respectively; relative risk, 1.88; 95% confidence interval, 0.93-3.79; P=0.079. Long term prophylaxis lasted from 1 to >10 years. No thrombosis or new inhibitors occurred. In conclusion, a subset of patients with factor VII deficiency needed prophylaxis because of severe bleeding. Recombinant activated factor VII schedules based on “frequent” administrations (three times weekly) and a 90 μg/kg total weekly dose were effective. These data provide a rationale for long-term, safe prophylaxis in factor VII deficiency (clinicaltrials.gov: NCT01269138).

A retrospective analysis of 157 surgical procedures performed without replacement therapy in 83 unrelated factor VII-deficient patients.

Summary.  Background: Inherited factor (F)VII deficiency is the commonest of the rare bleeding disorders, with a wide set of hemorrhagic features. Other than for the severe clinical forms (for which treatment guidelines are well defined), consistent recommendations regarding perioperative replacement management do not exist for mild and asymptomatic FVII‐deficient patients. Objectives: The present study aimed to evaluate the influence of bleeding history, FVII procoagulant activity levels (FVII:C) and the type of surgical procedure on the management of inherited FVII‐deficient patients before surgery. Patients: One hundred and fifty‐seven surgical procedures, performed without replacement therapy, in 83 unrelated FVII‐deficient patients (median FVII:C = 5%, range 0.6%–35%) were analyzed. Results: The overall bleeding rate was 15.3%. We found a significant relationship between previous deep traumatic hematomas and bleeding at surgery, although relationships with previous common epistaxis, easy bruising and menorrhagia were not significant. The receiver‐operating characteristic (ROC) curve analysis performed on the first 83 procedures allowed us to define a cut‐off value of 7% with a sensitivity of 87% (negative predictive value: 94%). To enhance the sensitivity, and to take into account the potential variation resulting from non‐standardized FVII:C measurements, we would suggest applying a threshold of 10%. Conclusion: We have proposed recommendations for the perioperative management of FVII‐deficient patients based on FVII:C levels, a thorough bleeding history and the type of surgery involved. By applying these recommendations, minor procedures that risk only external or controlled hemorrhage can be performed in asymptomatic or mildly affected adults, even those with FVII:C levels below 10%.

Potential predictors of bleeding risk in inherited factorVII deficiency Clinical, biological and molecular criteria

Due to the wide molecular and clinical heterogeneities of inherited factor VII (FVII) deficiency, consensus guidelines for management of this coagulation disorder are not currently well established. Therefore, potential clinical, plasmatic or genetic criteria, that could be predictive for bleeding tendency in this condition, have been evaluated. Genotypic criteria including FVII genotypes and thrombophilic mutations are of particular interest to better understand some of the variations observed in bleeding phenotypes but they are still poorly informative for the management of surgery in FVII-deficient patients. Up to now, no plasma parameters have been found to be reliable predictors of bleeding risk. Nevertheless, tissue factor and platelet pathways remain to be explored. Finally, clinical history appears to be the best predictor of bleeding risk after haemostatic challenges in inherited FVII deficiencies. Furthermore, the absence of history of bleeding or mild bleeding phenotypes including menorrhagia, bruises and epistaxis (not inducing iron deficiency anaemia or requiring blood substitutive treatment) could enable minor surgery to be performed in FVII-deficient patients without blood replacement therapy.

Invasive procedures and minor surgery in factor VII deficiency.

G. MARIANI ,* A. DOLCE, M. NAPOLITANO,* J . INGERSLEV, M. GIANSILY-BLAIZOT,§ M. D. DI MINNO,– G. AUERSWALD,** A. R. DE SAEZ, A. TAGLIAFERRI and A. BATOROVA§§ ON BEHALF OF THE STER (SEVEN TREATMENT EVALUATION REGISTRY) ; OTHER AUTHORS ARE LISTED AT THE END OF THE MANUSCRIPT *University of L Aquila, Dipartimento di Medicina Interna e Sanità, L Aquila, Italy; National Institute of Statistics, Palermo, Italy; University Hospital Skejby, Centre for Haemophilia and Thrombosis, Aarhus, Denmark; §Laboratory of Haematology, University Hospital, Montpellier, France; –Dipartimento di Medicina Clinica e Sperimentale, Centro di Coordinamento regionale per le Emocoagulopatie, Università di Napoli Federico II Naples, Italy; **Children s Hospital Organisation, Klinikum Bremen-Mitte, Bremen, Germany; National Haemophilia Centre, Banco Metropolitano de Sangre DC, Caracas, Venezuela; Centro Emofilia e Trombosi, Ospedale Regionale di Parma, Italy; and §§The National Haemophilia Centre, Institute of Haematology and Blood Transfusion, University Hospital, Bratislava, Slovakia

Thrombin Generation Measurement in Factor VII-Depleted Plasmas Compared to Inherited Factor VII-Deficient Plasmas

Activated factor VII (FVIIa)/tissue factor enzyme complex is the initiator of the coagulation cascade in vivo. FVIIa is of particular interest because it has been found to induce haemostasis in various bleeding disorders. In order to evaluate the FVII threshold that is required to initiate the clotting cascade, we measured thrombin generation in FVII-depleted plasmas spiked with increasing amounts of normal pooled plasma and in inherited FVII-deficient plasmas. According to the literature, only trace amounts of FVII are sufficient to initiate blood coagulation in vitro. By contrast, results on inherited FVII-deficient plasmas showed a wide variety of the amounts of thrombin generated in plasmas with the same FVII coagulant activity levels. This suggests that the threshold of FVII required to initiate haemostasis in vivo depends on one or more, hitherto unknown, plasmatic or cellular factors.

The Southern French registry of genetic hemochromatosis: a tool for determining clinical prevalence of the disorder and genotype penetrance

Background Despite great progress in understanding the mechanisms underlying genetic hemochromatosis, data on the prevalence and the penetrance of the disorder are conflicting. Design and Methods A registry of patients with genetic hemochromatosis was established in the South of France and a regional health network was developed to allow the inclusion of all the diagnosed patients. C282Y homozygous patients classified in stages 2 (biological iron overload), 3 and 4 (clinical manifestations of iron overload, stage 4 being the more severe) according to the classification of the French National Authority for Health were included in the registry over a 6-year period. Results A total of 352 symptomatic C282Y homozygotes were identified, resulting in a total prevalence of 1.83 per 10,000 (95% CI: 1.63 to 2.02) in subjects over 20 years and 2.40 per 10,000 (95% CI, 2.15 to 2.65) among subjects of European descent. Among Europeans, the total calculated penetrance was 15.8% in stage 2 or higher, 12.1% in stage 3 or 4 and 2.9% in stage 4. The penetrance was slightly higher in males (18.7%) than in females (13.2%). It was 19.9% for individuals over 40 years of age (24.1% and 16.3% in males and females, respectively) with a maximum of 31% in subjects between 50 and 54 years old. Among 249 patients with complete records, 24% were in stage 2, the majority (58%) were in stage 3, and 18% in stage 4. There was a higher proportion of males, and excessive alcohol intake was more prevalent in stage 4 than in stages 2 and 3 combined. Conclusions A French Mediterranean regional hemochromatosis registry with strict inclusion criteria is a useful tool for characterizing the history of this disease, particularly for the most severely affected patients, as defined by the disease severity classification. The total prevalence of symptomatic C282Y homozygotes in the region was found to be low. However, clinical penetrance (stages 3 and 4) was not negligible.

Is the coexistence of thromboembolic events and Factor VII deficiency fortuitous

Over 30 thromboembolic events have been reported in factor VII (FVII) deficiency either associated with previously asymptomatic forms or bleeding diathesis. Whether this coexistence is fortuitous or not is still a mater of debate. Nevertheless, it is well admitted that (i) thrombotic events occurring in FVII-deficient patients with any apparent triggering factors are very rare, (ii) surgical procedures, replacement therapy (especially containing activated factors) but also the presence of an antiphospholipid syndrome are frequently associated with these particular thrombotic events, (iii) in the same way, R304Q and A294V FVII variants appear to be more prevalent than other FVII equally frequent mutations and finally (iv) low FVII coagulant activity levels do not protect against thrombosis. Therefore, peri-operative thrombotic prophylaxis should be relevant for these particular FVII-deficient patients. However, safety, treatment modalities and specific indications of such an antithrombotic prophylaxis remain to be established.

Successful prophylaxis against intracranial hemorrhage using weekly administration of activated recombinant factor VII in a newborn with severe factor VII deficiency

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Coagulation factor VII variants resistant to inhibitory antibodies

Replacement therapy is currently used to prevent and treat bleeding episodes in coagulation factor deficiencies. However, structural differences between the endogenous and therapeutic proteins might increase the risk for immune complications. This study was aimed at identifying factor (F)VII variants resistant to inhibitory antibodies developed after treatment with recombinant activated factor VII (rFVIIa) in a FVII-deficient patient homozygous for the p.A354V-p.P464Hfs mutation, which predicts trace levels of an elongated FVII variant in plasma. We performed fluorescent bead-based binding, ELISA-based competition as well as fluorogenic functional (activated FX and thrombin generation) assays in plasma and with recombinant proteins. We found that antibodies displayed higher affinity for the active than for the zymogen FVII (half-maximal binding at 0.54 ± 0.04 and 0.78 ± 0.07 BU/ml, respectively), and inhibited the coagulation initiation phase with a second-order kinetics. Isotypic analysis showed a polyclonal response with a large predominance of IgG1. We hypothesised that structural differences in the carboxyl-terminus between the inherited FVII and the therapeutic molecules contributed to the immune response. Intriguingly, a naturally-occurring, poorly secreted and 5-residue truncated FVII (FVII-462X) escaped inhibition. Among a series of truncated rFVII molecules, we identified a well-secreted and catalytically competent variant (rFVII-464X) with reduced binding to antibodies (half-maximal binding at 0.198 ± 0.003 BU/ml) as compared to the rFVII-wt (0.032 ± 0.002 BU/ml), which led to a 40-time reduced inhibition in activated FX generation assays. Taken together our results provide a paradigmatic example of mutation-related inhibitory antibodies, strongly support the FVII carboxyl-terminus as their main target and identify inhibitor-resistant FVII variants.