Von Willebrand factor propeptide and pathophysiological mechanisms in European and Iranian patients with type 3 von Willebrand disease enrolled in the 3WINTERS-IPS study

Background Type 3 von Willebrand disease (VWD) is a severe bleeding disorder caused by the virtually complete absence of von Willebrand factor (VWF). Pathophysiological mechanisms of VWD like defective synthesis, secretion, and clearance of VWF have previously been evaluated using ratios of VWF propeptide (VWFpp) over VWF antigen (VWF:Ag) and factor (F)VIII coagulant activity (FVIII:C) over VWF:Ag. Objective To investigate whether the VWFpp/VWF:Ag and FVIII:C/VWF:Ag ratios may also be applied to understand the pathophysiological mechanism underlying type 3 VWD and whether VWFpp is associated with bleeding severity. Methods European and Iranian type 3 patients were enrolled in the 3WINTERS-IPS study. Plasma samples and buffy coats were collected and a bleeding assessment tool was administered at enrolment. VWF:Ag, VWFpp, FVIII:C, and genetic analyses were performed centrally, to confirm patients' diagnoses. VWFpp/VWF:Ag and FVIII:C/VWF:Ag ratios were compared among different variant classes using the Mann-Whitney test. Median differences with 95% confidence intervals (CI) were estimated using the Hodges-Lehmann method. VWFpp association with bleeding symptoms was assessed using Spearman's rank correlation. Results Homozygosity/compound heterozygosity for missense variants showed higher VWFpp level and VWFpp/VWF:Ag ratio than homozygosity/compound heterozygosity for null variants ([VWFpp median difference, 1.4 IU/dl; 95% CI, 0.2-2.7; P = .016]; [VWFpp/VWF:Ag median difference, 1.4; 95% CI, 0-4.2; P = .054]). FVIII:C/VWF:Ag ratio was similarly increased in both. VWFpp level did not correlate with the bleeding symptoms (r = .024; P = .778). Conclusions An increased VWFpp/VWF:Ag ratio is indicative of missense variants, whereas FVIII:C/VWF:Ag ratio does not discriminate missense from null alleles. The VWFpp level was not associated with the severity of bleeding phenotype.Peer reviewe

Effects Of L-Carnitine Supplement On Plasma Coagulation And Anticoagulation Factors In Hemodialysis Patients

Hypercoagulability is an important risk factor for thrombosis and its complications in hemodialysis patients. This study was designed to investigate the effects of L-carnitine supplement on plasma coagulation and anticoagulation factors in hemodialysis patients. Methods: Thirty-six hemodialysis patients were randomly assigned to either a carnitine or a placebo group. Patients in the carnitine group received 1000 mg/day oral L-carnitine for12 weeks, whereas patients in the placebo group received a corresponding placebo. At baseline and the end of week12, 5 mL blood was collected after a 12- to 14-hour fast and plasma fibrinogen concentration, activity of plasma proteinC, coagulation factors V, VII, IX, and serum concentrations of tissue plasminogen activator (tPA), plasminogen activator inhibitor type-1 (PAI-1), free carnitine, and C-reactive protein (CRP) were measured. Results: In the carnitine group, mean serum free carnitine concentration increased significantly to 150% of baseline (p < 0.001), whereas plasma fibrinogen and serum CRP had 98 mg/dL (p < 0.01) and 41% (p < 0.01) significant decreases, respectively, at the end of week 12 compared with baseline. The reductions were significant compared with the placebo group (p < 0.05).No significant differences were observed between the two groups with regard to mean changes of the activity of plasma protein C, coagulation factors V, VII, IX, and serum PAI-1 to tPA ratio. Conclusion: L-Carnitine supplement reduces serum CRP, a marker of systemic inflammation, and plasma fibrinogen, an inflammation-related coagulation factor, in hemodialysis patients. Therefore, L-carnitine may play an effective role in preventing cardiovascular diseases in these patients

Evaluation of platelet aggregation in splenectomized beta-thalassemia major and intermedia patients

BACKGROUND: Platelet dysfunction may be one of the pathophysiologic complications in beta-thalassemia patients. However, the results obtained from the platelet aggregation vary in different types of β-thalassemia and among patients. OBJECTIVE: We evaluated the platelet function to determine risk of thrombosis in two groups': beta-thalassemia major (TM) and intermedia (TI). MATERIALS AND METHODS: In a cross-sectional study, platelets of 82 adult patients with beta-thalassemia (46 β-TM and 36 β-TI) who had undergone splenectomy and 85 normal healthy individuals as control were induced by collagen 10 μ g/ml, adenosine diphosphate (ADP) 20 μ M/l, arachidonic acid 500 μ M/l, and ristocetin 1500 μ g/ml. Independent t-test was used to compare the mean values using SPSS 16. P < 0.05 was taken to indicate statistical significance. RESULTS: Although a significant increase was observed in the platelet aggregation by collagen, ADP, and arachidonic acid in β-TM patients as compared with healthy controls, the β-TI patients showed no difference (P < 0.05). There was no significant alteration in response to ristocetin in β-TM but it reduced in β-TI. CONCLUSIONS: The platelet aggregation in β-TM patients is more than β-TI, both of whom splenectomized. The platelet aggregation in beta-thalassemia might be impressed by transfusion. Given these changes, thrombotic risk should be considered in beta-thalassemia patients

von Willebrand factor neutralizing and non-neutralizing alloantibodies in 213 subjects with type 3 von Willebrand disease enrolled in 3WINTERS-IPS

Background: Type 3 von Willebrand disease (VWD) is the most severe form of this disease owing to the almost complete deficiency of von Willebrand factor (VWF). Replacement therapy with plasma-derived products containing VWF or recombinant VWF rarely cause the development of alloantibodies against VWF that may be accompanied by anaphylactic reactions. Objective: The objective of this study was to assess the prevalence of anti-VWF alloantibodies in subjects with type 3 VWD enrolled in the 3WINTERS-IPS. Methods: An indirect in-house enzyme-linked immunosorbent assay has been used to test all the alloantibodies against VWF. Neutralizing antibodies (inhibitors) have been tested with a Bethesda-based method by using a VWF collagen binding (VWF:CB) assay. Samples positive for anti-VWF antibodies were further tested with Bethesda-based methods by using the semiautomated gain-of-function glycoprotein-Ib binding (VWF:GPIbM) and a VWF antigen (VWF:Ag) enzyme-linked immunosorbent assay. Results: In total, 18 of the 213 (8.4%) subjects tested positive for anti-VWF antibodies and 13 of 213 (6%) had VWF:CB inhibitors. These 13 were among the 18 with anti-VWF antibodies. Of the 5 without VWF:CB inhibitors, 3 had non-neutralizing antibodies, 1 only inhibitor against VWF:GPIbM, and one could not be tested further. Ten of the 13 subjects with VWF:CB inhibitors also had VWF:GPIbM inhibitors, 6 of whom also had VWF:Ag inhibitors. Subjects with inhibitors were homozygous for VWF null alleles (11/14), homozygous for a missense variant (1/14), or partially characterized (2/14). Conclusions: Anti-VWF antibodies were found in 8.4% of subjects with type 3 VWD, whereas neutralizing VWF inhibitors were found in 6%, mainly in subjects homozygous for VWF null alleles. Because inhibitors may be directed toward different VWF epitopes, their detection is dependent on the assay used

Genotypes of European and Iranian patients with type 3 von Willebrand disease enrolled in 3WINTERS-IPS

Type 3 von Willebrand disease (VWD3) is a rare and severe bleeding disorder characterized by often undetectable von Willebrand factor (VWF) plasma levels, a recessive inheritance pattern, and heterogeneous genotype. The objective of this study was to identify the VWF defects in 265 European and Iranian patients with VWD3 enrolled in 3WINTERS-IPS (Type 3 Von Willebrand International Registries Inhibitor Prospective Study). All analyses were performed in centralized laboratories. The VWF genotype was studied in 231 patients with available DNA (121 [115 families] from Europe [EU], and 110 [91 families] from Iran [IR]). Among 206 unrelated patients, 134 were homozygous (EU/IR 5 57/77) and 50 were compound heterozygous (EU/IR 5 43/7) for VWF variants. In 22 patients, no or only one variant was found. A total of 154 different VWF variants (EU/IR 5 101/58 [5 shared]) were identified among the 379 affected alleles (EU/IR 5 210/169), of which 48 (EU/IR 5 18/30) were novel. The variants p.Arg1659*, p.Arg1853*, p.Arg2535*, p.Cys275Ser, and delEx1_Ex5 were found in both European and Iranian VWD3 patients. Sixty variants were identified only in a single allele (EU/IR 5 50/10), whereas 18 were recurrent ($3 patients) within 144 affected alleles. Nine large deletions and one large insertion were found. Although most variants predicted null alleles, 21% of patients carried at least 1 missense variant. VWD3 genotype was more heterogeneous in the European population than in the Iranian population, with nearly twice as many different variants. A higher number of novel variants were found in the Iranian VWD3 patients