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| 2. |
- Collins, P. W., et al.
(författare)
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Break-through bleeding in relation to predicted factor VIII levels in patients receiving prophylactic treatment for severe hemophilia A
- 2009
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Ingår i: Journal of Thrombosis and Haemostasis. - : Elsevier BV. - 1538-7933 .- 1538-7836. ; 7:3, s. 413-420
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: The role of prophylactic factor VIII (FVIII) to decrease hemophilic bleeding and arthropathy is well established. The rationale for this strategy is to convert patients with severe hemophilia A to a moderate clinical phenotype by reducing time spent with a FVIII level <1 IU dL(-1). Studies to date, however, have not demonstrated a strong link between FVIII level and the bleeding rate. OBJECTIVES: To assess the effect of FVIII level on break-through bleeding in patients with severe hemophilia A on prophylaxis. PATIENTS/METHODS: This study analysed data from 44 patients aged 1-6 and 99 patients aged 10-65 years with severe hemophilia A (FVIII <1 IU dL(-1)) who were treated with prophylactic FVIII as part of clinical studies assessing pharmacokinetics, safety and efficacy of a recombinant FVIII (Advate). Each patient had pharmacokinetic measurements and FVIII infusions recorded, and these were used to calculate time spent with a FVIII below 1, 2 and 5 IU dL(-1). RESULTS: The data demonstrate that increasing time with a FVIII below 1 IU dL(-1) is associated with increased total bleeds and hemarthroses. Lack of adherence to the intended frequency of FVIII infusion was the most important determinant of low FVIII and increased bleeding. In children aged 1-6 years, the rate of bleeding was also influenced by FVIII half-life and clearance. Conclusions: These data have important implications for the management of patients with severe hemophilia.
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| 4. |
- Pavlova, A., et al.
(författare)
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Impact of polymorphisms of the major histocompatibility complex class II, interleukin-10, tumor necrosis factor-alpha and cytotoxic T-lymphocyte antigen-4 genes on inhibitor development in severe hemophilia A
- 2009
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Ingår i: Journal of Thrombosis and Haemostasis. - : Elsevier BV. - 1538-7933 .- 1538-7836. ; 7:12, s. 2006-2015
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Tidskriftsartikel (refereegranskat)abstract
- Background: Approximately 25% of severe hemophilia A (HA) patients develop antibodies to factor VIII protein. Patients: In the present case-controlled cohort study, 260 severely affected, mutation-type-matched HA patients were studied for association of human leukocyte antigen (HLA) class II molecules and polymorphisms in the genes encoding interleukin-10 (IL-10), tumor necrosis factor-alpha (TNF-alpha) and cytotoxic T-lymphocyte antigen-4 (CTLA-4) and development of inhibitors. Results: Our results demonstrate a higher frequency of DRB1*15 and DQB1*0602 alleles as well as of the haplotype DRB1*15/DQB1*0602 in inhibitor patients [odds ratio (OR) 1.9; P < 0.05]. In TNF-alpha, the A allele of the -308G > A polymorphism was found with higher frequency in the inhibitor cohort (0.22 vs. 0.13, OR 1.80). This finding was more pronounced for the homozygous A/A genotype (OR 4.7). For IL-10, the -1082G allele was observed more frequently in patients with inhibitors (0.55 vs. 0.43; P = 0.008). The functional cytokine phenotype was determined for the first time, on the basis of the genetic background, and this showed that 12% of patients with inhibitors were high-TNF-alpha/high-IL-10 producers, as compared with 3% of non-inhibitor patients (OR 4.4). A trend for a lower frequency of the A allele of the CT60 polymorphism in CTLA-4 was found in inhibitor patients (0.42 vs. 0.50). Conclusions: In conclusion, the reported data clearly highlighted the participation of HLA molecules in inhibitor formation in a large cohort of patients. The higher frequencies of the -308G > A polymorphism in TNF-alpha and -1082A > G in IL-10 in inhibitor patients confirmed the earlier published data. The CT60 single-nucleotide polymorphism in CTLA-4 is of apparently less importance.
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| 5. |
- Varadi, K, et al.
(författare)
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Monitoring the bioavailability of FEIBA with a thrombin generation assay
- 2003
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Ingår i: Journal of Thrombosis and Haemostasis. - : Elsevier BV. - 1538-7933 .- 1538-7836. ; 1:11, s. 2374-2380
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Tidskriftsartikel (refereegranskat)abstract
- Background: Hemophilia A patients with inhibitors are generally treated with preparations containing activated coagulation factors to achieve hemostasis by bypassing factor (F)VIII. Objectives: We developed an assay for monitoring the kinetic of thrombin generation in human FVIII inhibitor plasma reconstituted in vitro with activated prothrombin complex concentrate, FEIBA, and in plasma samples from hemophilia A patients taken after FEIBA treatment. Patients and methods: For pharmacokinetic studies three patients with severe hemophilia A and with a high-titer inhibitor received a single dose of FEIBA. Repeated FEIBA treatment was monitored in one patient with acquired hemophilia A. Coagulation was triggered in citrated plasma by adding a low concentration of tissue factor/phospholipid complex and CaCl2 in the presence of a fluorogenic thrombin substrate. The intensity of the fluorescence signal (FU) was continuously monitored, and the rate of increase in the fluorescence signal for every time point, which reflects the actual thrombin concentrations, was calculated. Results: The maximum rate of substrate conversion, which indicates the highest thrombin concentration, was approximately 1900 FU min(-1) in a normal plasma pool. Practically no thrombin generation was observed in the FVIII inhibitor plasma, but when it was spiked with FEIBA, the rate and the peak of thrombin generation increased dose-dependently to close to normal. Plasma samples from FVIII inhibitor patients treated with a single dose of FEIBA had an improved thrombin maximum within an hour after treatment, which gradually returned to baseline values with a half-life of 4-7 h. Changes in the characteristic parameters of thrombin generation coincided with the repeated administration of FEIBA in a patient with acquired hemophilia A. Conclusions: This assay enables the pharmacodynamic and pharmacokinetic properties of bypassing therapies to be monitored, thus helping to optimize treatment.
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| 6. |
- Mariani, G, et al.
(författare)
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Thrombosis in inherited factor VII deficiency
- 2003
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Ingår i: Journal of thrombosis and haemostasis : JTH. - : Elsevier BV. - 1538-7933 .- 1538-7836. ; 1:10, s. 2153-2158
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Tidskriftsartikel (refereegranskat)
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| 7. |
- Eckhardt, C. L., et al.
(författare)
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The Fc gamma receptor IIa R131H polymorphism is associated with inhibitor development in severe hemophilia A
- 2014
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Ingår i: Journal of Thrombosis and Haemostasis. - : Elsevier BV. - 1538-7933 .- 1538-7836. ; 12:8, s. 1294-1301
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Tidskriftsartikel (refereegranskat)abstract
- Background: The development of factor (F) VIII neutralizing alloantibodies (inhibitors) is a major complication of treatment with FVIII concentrates in hemophilia A and the etiology is still poorly understood. The low-affinity Fc gamma receptors (Fc gamma R), which are expressed on immune cells, provide an important link between cellular and humoral immunity by interacting with IgG subtypes. Genetic variations of the genes encoding Fc gamma Rs (FCGR genes) have been associated with susceptibility to infectious and autoimmune diseases. Objectives: The aim of this study was to investigate the association between genetic variation of FCGR and inhibitor development in severe hemophilia A. Patients/Methods: In this case-control study samples of 85 severe hemophilia A patients (siblings from 44 families) were included. Single nucleotide polymorphisms and copy number variation of the FCGR2 and FCGR3 gene cluster were studied in an FCGR-specific multiplex ligation-dependent probe amplification assay. Frequencies were compared in a generalized estimating equation regression model. Results: Thirty-six patients (42%) had a positive history of inhibitor development. The polymorphism 131R > H in the FCGR2A gene was associated with an increased risk of inhibitor development (odds ratio [OR] per H-allele, 1.8; 95% confidence interval [CI], 1.1-2.9). This association persisted in 29 patients with high titer inhibitors (OR per H-allele, 1.9; 95% CI, 1.2-3.2) and in 44 patients with the F8 intron 22 inversion (OR per H-allele, 2.6; 95% CI, 1.1-6.6). Conclusions: Hemophilia A patients with the HH genotype of the FCGR2A polymorphism 131R > H have a more than 3-fold increased risk of inhibitor development compared with patients with the RR genotype.
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| 8. |
- Manderstedt, Eric, et al.
(författare)
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Detection of F8 int22h inversions using digital droplet PCR and mile-post assays
- 2020
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Ingår i: Journal of Thrombosis and Haemostasis. - : Wiley-Blackwell. - 1538-7933 .- 1538-7836. ; 8:5, s. 1039-1049
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Inversions involving intron 22 (Inv22) of F8 are detected in approximately 45% of all severe hemophilia A patients. Diagnosis is complicated by the large size of the ~9.5 kb int22h repeated sequence which generates the inversions. Methods such as long-range PCR and inverse-shifting PCR are currently used diagnostically, but suffer from low PCR efficiencies and are difficult to standardize.OBJECTIVES: To design and validate a sensitive and robust assay for the detection of F8 int22h inversions.METHODS: Digital droplet PCR using mile-post assays was used to investigate archival DNA samples.RESULTS: The detection of linkage as a function of physical distance between loci was investigated using an anchor locus and mile-post loci located at 1, 6, 12 and 15 kb distances from the anchor locus. The proportion of linked molecules decreased with increasing distance between loci and showed 30-40% linked molecules for loci 12-15 kb apart. Mile-post assays specific for wild type and Inv22 type 1 and 2 chromosomes were then designed and optimized. All three assays showed high specificities and sensitivities, with coefficients of variation < 5% for all assays. Analysis of 106 patients and 20 carrier mothers showed complete concordance with previously known mutation status. The analysis demonstrated the robustness of the assays versus input DNA concentration (6 ng and higher) and level of fragmentation.CONCLUSIONS: Digital droplet PCR and mile-post assays can be used to detect F8 int22h inversions. The assay systems are technically simple to perform, highly efficient and robust.
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| 9. |
- Manderstedt, Eric, et al.
(författare)
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Detection of F8 int22h inversions using digital droplet PCR and mile-post assays
- 2020
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Ingår i: Journal of Thrombosis and Haemostasis. - : Wiley-Blackwell Publishing Ltd. - 1538-7933 .- 1538-7836. ; 8:5, s. 1039-1049
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Inversions involving intron 22 (Inv22) of F8 are detected in approximately 45% of all severe hemophilia A patients. Diagnosis is complicated by the large size of the ~9.5 kb int22h repeated sequence which generates the inversions. Methods such as long-range PCR and inverse-shifting PCR are currently used diagnostically, but suffer from low PCR efficiencies and are difficult to standardize. OBJECTIVES: To design and validate a sensitive and robust assay for the detection of F8 int22h inversions. METHODS: Digital droplet PCR using mile-post assays was used to investigate archival DNA samples. RESULTS: The detection of linkage as a function of physical distance between loci was investigated using an anchor locus and mile-post loci located at 1, 6, 12 and 15 kb distances from the anchor locus. The proportion of linked molecules decreased with increasing distance between loci and showed 30-40% linked molecules for loci 12-15 kb apart. Mile-post assays specific for wild type and Inv22 type 1 and 2 chromosomes were then designed and optimized. All three assays showed high specificities and sensitivities, with coefficients of variation < 5% for all assays. Analysis of 106 patients and 20 carrier mothers showed complete concordance with previously known mutation status. The analysis demonstrated the robustness of the assays versus input DNA concentration (6 ng and higher) and level of fragmentation. CONCLUSIONS: Digital droplet PCR and mile-post assays can be used to detect F8 int22h inversions. The assay systems are technically simple to perform, highly efficient and robust.
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| 10. |
- Manderstedt, Eric, et al.
(författare)
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Droplet digital PCR and mile-post analysis for the detection of F8 int1h inversions
- 2021
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Ingår i: Journal of Thrombosis and Haemostasis. - : Wiley-Blackwell. - 1538-7933 .- 1538-7836. ; 19:3, s. 732-737
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: F8 int1h inversions (Inv1) are detected in 1-2% of severe hemophilia A (HA) patients. Long-range polymerase chain reaction (PCR) and inverse-shifting PCR have been used to diagnose these inversions.OBJECTIVES: To design and validate a sensitive and robust assay for detection of F8 Inv1 inversions.METHODS: Archival DNA samples were investigated using mile-post assays and droplet digital PCR.RESULTS: Mile-post assays for Inv1 showing high specificities and sensitivities were designed and optimized. Analysis of four patients, two carrier mothers and 40 healthy controls showed concordance with known mutation status with one exception. One patient had a duplication involving exons 2-22 of the F8 gene instead of an Inv1 mutation. DNA mixtures with different proportions of wild type and Inv1 DNA correlated well with the observed relative linkage for both wild type and Inv1 assays and estimated the limit of detection of these assays to 2% of the rare chromosome.CONCLUSIONS: The mile-post strategy has several inherent control systems. The absolute counting of target molecules by both assays enables determination of template quantity, detection of copy number variants and rare variants occurring in primer and probe annealing sites and estimation of DNA integrity through the observed linkage. The presented Inv1 mile-post analysis offers sensitive and robust detection and quantification of the F8 int1h inversions and other rearrangements involving intron 1 in patients and their mothers.
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