Congenital fibrinogen disorders are caused by mutations in one of the three fibrinogen genes that affect the synthesis, assembly, intracellular processing, stability or secretion of fibrinogen. Functional studies of mutant Bβ-chains revealed the importance of individual residues as well as three-dimensional structures for fibrinogen assembly and secretion. This study describes two novel homozygous fibrinogen Bβ chain mutations in two Slovak families with afibrinogenemia and hypofibrinogenemia. Peripheral blood samples were collected from all subjects with the aim of identifying the causative mutation. Coagulation-related tests and rotational thromboelastometry were performed. All exons and exon–intron boundaries of the fibrinogen genes (FGA, FGB and FGG) were amplified by PCR followed by direct sequencing. Sequence analysis of the three fibrinogen genes allowed us to identify two novel homozygous mutations in the FGB gene. A novel Bβ chain truncation (BβGln180Stop) was detected in a 28-year-old afibrinogenemic man with bleeding episodes including repeated haemorrhaging into muscles, joints, and soft tissues, and mucocutaneous bleeding and a novel Bβ missense mutation (BβTyr368His) was found in a 62-year-old hypofibrinogenemic man with recurrent deep and superficial venous thromboses of the lower extremities. The novel missense mutation was confirmed by molecular modelling. Both studying the molecular anomalies and the modelling of fibrinogenic mutants help us to understand the extremely complex machinery of fibrinogen biosynthesis and finally better assess its correlation with the patient’s clinical course.

The aim of this study was to evaluate the genetic variability of the selected single nucleotide polymorphisms (SNPs) and examine the association between these SNPs and risk for deep vein thrombosis (DVT) in patients with sticky platelet syndrome (SPS). We examined 84 patients with SPS and history of DVT and 101 healthy individuals. We were interested in 2 SNPs within platelet endothelial aggregation receptor 1 (PEAR1) gene (rs12041331 and rs12566888), 2 SNPs within mkurine retrovirus integration site 1 gene (rs7940646 and rs1874445), 1 SNP within Janus kinase 2 gene (rs2230722), 1 SNP within FCER1G gene (rs3557), 1 SNP within pro-platelet basic protein (rs442155), 4 SNPs within alpha2A adrenergic receptor 2A (ADRA2A; rs1800545, rs4311994, rs11195419, and rs553668), and 1 SNP within sonic hedgehog gene (rs2363910). We identified 2 protective SNPs within PEAR1 gene and 1 risk SNP within ADRA2A gene (PEAR1: rs12041331 and rs12566888; ADRA2A: rs1800545). A haplotype analysis of 4 SNPs within ADRA2A gene identified a risk haplotype aagc (P = .003). Moreover, we identified 1 protective haplotype within PEAR1 gene (AT, P = .004). Our results support the idea that genetic variability of PEAR1 and ADRA2A genes is associated with platelet hyperaggregability manifested as venous thromboembolism. The study also suggests a possible polygenic type of SPS heredity.

Introduction The aim of this study was to evaluate the genetic variability of selected single nucleotide polymorphisms (SNPs) within GAS6 and PEAR1 genes and explore the association between selected SNPs and risk for fetal loss in women with sticky platelet syndrome (SPS). Materials and Methods We examined 23 female patients with SPS and history of spontaneous abortion, and 42 healthy women who served as controls. The diagnosis of SPS was established by light transmission aggregometry according to methods and criteria developed by Mammen et al. We also assessed four SNPs within the GAS6 gene (rs7400002, rs1803628, rs8191974, rs9550270) and two SNPs within PEAR1 gene (rs12041331, rs12566888). Results We identified two SNPs within PEAR1 gene (rs12041331, rs12566888) and one SNP within GAS6 gene (rs9550270) that have higher occurrence in SPS patients with history of abortion. An increased risk for abortion was observed in carriers of the rs7400002 within GAS6 gene. Conversely, we found that the T allele of PEAR1 c. -9–4663G > T polymorphism appears to be protective for fetal loss. Conclusion Our results support the idea that genetic variability of GAS6 and PEAR1 genes may be associated with platelet hyperaggregability. The study also suggests a possible polygenic type of SPS heredity.

We read with great interest the article by Curnow et al, [1] describing treatment of von Willebrand disease (VWD), as published in a recent issue of the journal, together with other interesting articles related to such disorders, as appearing in a recent issue of Seminars in Thrombosis & Hemostasis. We therefore wish to report our experience of the first successful use of a highly purified plasma von Willebrand factor (VWF) concentrate containing little FVIII in the long-term prophylaxis of severe vWD in Slovakia. VWD is the most common inherited bleeding disorder caused by a quantitative and/or qualitative abnormality in the adhesive plasma protein VWF.[2] VWF represents a high-molecular-weight adhesive glycoprotein that plays an essential role in the primary hemostasis by promoting platelet adhesion to the subendothelium and platelet plug formation at the sites of vascular injury. VWD is classified into three major types: partial quantitative deficiency (type 1), qualitative deficiency (type 2), and complete quantitative deficiency (type 3). VWD type 2 is further divided into four variants (2A, 2B, 2N, 2M), based on the characteristics of the dysfunctional VWF.[1] [3] Individuals presenting with clinical manifestations of VWD may have a mild, moderate, or severe bleeding tendency since childhood, usually proportional to the degree of the VWF deficiency/defect.[4] There are two principle treatments of choice in VWD: desmopressin (DDAVP) and substitution therapy with blood products containing VWF (with/without factor VIII; FVIII). Other forms of treatment can be considered as adjunctive or alternative to those mentioned above.[5] We present a male patient (now aged 34 years) with VWD type 3 ([Table 1]). Our study was conducted in accordance with the Declaration of Helsinki. It was also approved by the institutional ethics committee on human research and informed consent was obtained. Early after birth, several spontaneous bleeding manifestations presented, which, over subsequent years, continued with many mucosal and joint bleeding episodes; these promoted the development of arthropathy. Substitution therapy was historically administered “on demand” during these events. From 1999, the then 17-year-old patient was subsequently treated with regular prophylactic administration of VWF/FVIII plasma-derived concentrates. Despite preventive administration, the patient continued to have recurrent mucosal bleeding and epistaxis, albeit with less frequent bleeding into joints. From December 2015, he was switched from a concentrate containing both VWF and FVIII to a highly purified plasma VWF concentrate containing little FVIII (Willfact; LFB Biomedicaments, France). Levels of plasma VWF and FVIII in individuals with VWD can be regulated by the infusion of plasma-derived concentrates containing either VWF alone or VWF with FVIII.[1] Available concentrates contain different amounts of VWF and FVIII, and the appropriate dosage should, therefore, be defined according to the specific product's characteristics.[6] The primary symptoms of the severe form of VWD, comprising deficiency of both VWF and FVIII, may therefore comprise frequent hemophilia-like joint bleeds or recurrent spontaneous mucosal bleeding (e.g., epistaxis and gastrointestinal bleeding). Therefore, in patients with frequent bleeding, the treatment rationale is use of secondary long-term prophylaxis.[6] [7] Although patients with severe VWD produce FVIII, the lack of VWF prevents stabilization of the FVIII and leads to its early degradation and an inherent plasma FVIII deficiency. However, continued dosing with a VWF/FVIII concentrate may lead to excess plasma levels of FVIII, because the concentrate contains FVIII and also provides VWF that in turn stabilizes the patient's endogenous FVIII. To avoid excessive replacement therapy-induced FVIII levels, a highly purified plasma VWF concentrate containing little FVIII has been developed, mainly for use in VWD. Insufficient or excessive circulating levels of FVIII achieved with replacement treatment can lead to inadequate hemostatic response or, alternatively, to a potential risk of thromboembolic events.[8] Because of very low FVIII content, this particular VWF concentrate should be mainly used in patients unresponsive to DDAVP in situations such as surgical intervention and long-term prophylaxis; for surgical intervention, such a concentrate is suitable when patients have only a slightly reduced or normal FVIII levels. Our patient received the intravenous bolus dose 32 IU/kg of highly purified plasma VWF concentrate containing little FVIII. Bolus dose increased the levels of VWF/FVIII after 2 hours to corresponding VWF:RCo 0.295 IU/mL, VWF:Ag 0.701 IU/mL, and FVIII:C 0.223 IU/mL, respectively. The infused highly purified plasma VWF concentrate led to a rapid change of previously low levels of VWF/FVIII, to normalization of ristocetin-induced platelet aggregation (88%), and detection of VWF multimers ([Fig. 1]). The VWF plasma peak was reached between 30 minutes and 2 hours after administration. The VWF half-life was between 8 and 14 hours, with a mean value of 12 hours. Normalization of FVIII level was progressive, varied, and was usually between 6 and 12 hours. This effect was sustained for 2 to 3 days. The highest levels of FVIII:C was 0.324–0.284 IU/mL, VWF:RCo 0.261 to 0.151 IU/mL, VWF:Ag 0.564 to 0.173 IU/mL, and ristocetin-induced platelet aggregation 86 to 88% during the first 24 hours after administration. These data are similar to those by Castaman et al.[4] The concentrate was well tolerated and with no side effects. Clinical experience with secondary prophylaxis in VWD has been rated as excellent or good in the large majority of case series, despite use of different schedules of administration.[9] [10] In our patient, reporting a personal history of serious hemorrhage, the prophylactic administration of VWF/FVIII concentrates has been changed to that of...

The availability of direct oral anticoagulants has caused a paradigm shift in the management of thrombosis. Rivaroxaban and apixaban are 2 direct oral anticoagulants whose target specificity is activated factor X (FXa). However, it is still not fully understood if and how xabans impact platelet function. This observational study aimed to assess the in vitro platelet function in patients with atrial fibrillation receiving xabans. This was a single-center study quantifying platelet aggregation in 41 patients treated with apixaban or rivaroxaban by light transmission aggregometry. The thrombin receptor activating peptide (TRAP)-induced platelet aggregation was significantly lower 2 hours after taking rivaroxaban or apixaban compared to baseline value (56.15% [8.53%] vs 29.51% [12.9%]; P = .000). Moreover, concomitant use of angiotensin-converting enzyme blockers, proton pump inhibitors, and statins reduces the efficiency of xabans. The TRAP-induced platelet aggregation was reduced in patients with cardiovascular disease 2 hours after receiving xabans.

The availability of direct oral anticoagulants has caused a paradigm shift in thrombosis management. The direct thrombin inhibitor dabigatran seems to obstruct tenase complex by inhibiting thrombin generated in the initial phase and feed back to the amplification phase of cell-based coagulation reactions. However, it is still not fully understood if and how dabigatran impact platelet function. This observational study aimed to assess in vitro platelet function in patients with atrial fibrillation receiving dabigatran. Platelet aggregability was tested with platelet-rich plasma using platelet aggregometry (PACKS-4 aggregometer). Blood samples were stimulated with thrombin receptor agonist peptide (TRAP; 32 μmol/L). Results: A total of 28 patients with nonvalvular atrial fibrillation were enrolled. The mean age was 71.57 (9.75) years (range: 50-87 years), 16 patients were women, and the mean CHA₂DS₂VASc score was 3.93 (1.41). All patients began treatment with dabigatran as initial anticoagulant treatment. The minimum term use of dabigatran was 18 days. Dabigatran doses were 110 mg (57.14%) or 150 mg (42.86%) twice daily. The TRAP-induced platelet aggregation was significantly lower 2 hours after taking dabigatran compared to baseline value (79.39 [13.38] vs 90.14 [10.5]). Conclusion: The TRAP-induced platelet aggregation was reduced in cardiovascular patients 2 hours after receiving dabigatran. Our findings could have some important clinical implications because platelet aggregation and coagulation cascade are affected at the same time.