High Mutational Heterogeneity, and New Mutations in the Human Coagulation Factor V Gene. Future Perspectives for Factor V Deficiency Using Recombinant and Advanced Therapies

Factor V is an essential clotting factor that plays a key role in the blood coagulation cascade on account of its procoagulant and anticoagulant activity. Eighty percent of circulating factor V is produced in the liver and the remaining 20% originates in the α-granules of platelets. In humans, the factor V gene is about 80 kb in size; it is located on chromosome 1q24.2, and its cDNA is 6914 bp in length. Furthermore, nearly 190 mutations have been reported in the gene. Factor V deficiency is an autosomal recessive coagulation disorder associated with mutations in the factor V gene. This hereditary coagulation disorder is clinically characterized by a heterogeneous spectrum of hemorrhagic manifestations ranging from mucosal or soft-tissue bleeds to potentially fatal hemorrhages. Current treatment of this condition consists in the administration of fresh frozen plasma and platelet concentrates. This article describes the cases of two patients with severe factor V deficiency, and of their parents. A high level of mutational heterogeneity of factor V gene was identified, nonsense mutations, frameshift mutations, missense changes, synonymous sequence variants and intronic changes. These findings prompted the identification of a new mutation in the human factor V gene, designated as Jaén-1, which is capable of altering the procoagulant function of factor V. In addition, an update is provided on the prospects for the treatment of factor V deficiency on the basis of yet-to-be-developed recombinant products or advanced gene and cell therapies that could potentially correct this hereditary disorder.

Novel single nucleotide mutations in exon-10 of human coagulationFactor V gene in patients with pulmonary thromboembolism

Introduction: Acute pulmonary thromboembolism (PTE) presents with wide spectrum and has variable prognosis. Factor V Leiden (FVL) is the most common inherited thrombophilia, with a prevalence of 3%-7% in the general US population, approximately 5% in Whites, 2.2% in Hispanics and 1.2% in Blacks. PTE most commonly originates from venous thrombosis. The occurrence of venous thromboembolism is a culmination of environmental and genetic risk factors. The current study was sought to identify the mutations in exon-10 of FV gene in patients with PTE.<br /> Methods: Sixty cases diagnosed with PTE and 50 healthy controls were enrolled in the present study. Mutation studies in exon-10 of Factor V gene included PCR-DNA sequencing method.<br /> Results: Of 60 patients, we found two novel transition type point mutations: c.1538 G>A and c.1601 G>A in exon-10 of Factor V which is responsible for the cleavage site for aPC. These point mutations resulted in single amino acid change in protein sequence at p.Arg513Lys and p.Arg534Gln respectively. These mutations prevent efficient inactivation of Factor V and Factor V remains active which facilitates over production of thrombin leading to generation of excess fibrin and excess coagulation which results in deep vein thrombosis and PTE.<br /> Conclusion: We report two novel point mutations (c.1538 G>A and c.1601 G>A) in exon-10 of Factor V gene in Indian patients with PTE.

CONTRIBUTION OF THE G1691A ALLELE CARRYING OF THE COAGULATION FACTOR V GENE TO THE DEVELOPMENT OF THROMBOSES IN EXPOSED PATIENTS WITH REACTIVE CHANGES IN PERIPHERAL BLOOD

Thrombosis triggers, in addition to «classic» risk factors (RFs) of cardiovascular events, includes the reactive changes of peripheral blood (RCPB), markers of the hereditary thrombophilia and radiation anamnesis. However, results of most studies suggest the «classic» RFs are able to neutralize the prothrombogenic potential of the hereditary thrombophilia and other, less powerful predictors of thrombosis. Objective: to determine the influence of the G1691A allele of the proaccelerin gene carrying to the thrombosis development, taking into account the vascular type of their occurrence, the presence of RFs in individuals with RCPB (reactive leukocytosis and thrombocytosis, and secondary erythrocytosis), as well as with and without radiation anamnesis. Material and methods. In general, it was analyzed the results of clinical and molecular-genetic data of 152 patients with RCPB, 19 patients had radiation anamnesis, 133 – did not have. The thrombotic complications were detected in 5 (26.31 %) of radiation-exposer patients and 25 (18.79 %) patients without radiation anamneses. The carrying of the G1691A allele proaccelerin gene (APG) (Leiden mutation (LM)) was detected using the allele-specific polymerase chain reaction. Results. The LM was found in 5.9 % (9 carriers) of the general cohort (GC) of RPBC patients. There were no difference in the LM frequency between the groups of patients with and without radiation anamnesis (р = 0.312). In the group of radiation-exposer patients (р = 0.017), as well as in the group without its (р = 0.031), venous thromboses only were more frequently in the LM carriers. In the presence of a radiation anamnesis, G1691A APG carriers with RFs have the higher frequency (р = 0.008) and the probability of the occurrence (relative risk [RR] = 25.00; CI 95 %: 1.56–399.68) of venous thrombosis. In the group without radiation anamnesis, the frequency of venues thrombosis in the LM carriers is higher in the younger age subgroup (р = 0.001), without RFs (p = 0.044) and without RFs under 60 years (р = 0.023). The risk of venous thrombosis in the G1691A APG carriers of the group without radiation anamnesis is 5.78 (95 % CI: 1.58–21.13). In LM carriers without radiation anamnesis and RFs, as well as under the 60 years of age, the probability of venous thrombosis was 6.85 (95 % CI: 1.86–25.22) and 19.40 (95 % CI: 4.64–81.09), respectively, and in the absence of both criteria – 9.57 (95 % CI: 2.49–36.73). Conclusions. In patients with and without radiation anamnesis, the risk of venues thrombosis are observed more often in carriers of LM. The carrying of the G1691A APG in patients with RPBC and without RA increased the risk of venues thrombosis development in subjects without FRs and below 60 years of age. In the radiation-exposure group, the frequency and the risk of venues thrombosis in the G1691A APG carriers was higher in the subgroup with RFs. It is probably due to the peculiarity of the samples, or prothrombogenic interaction between LM and radiation-associated endothelial damage. Key words: reactive changes of peripheral blood, the G1691A allele of the coagulation factor V gene, risk factor of thrombosis.