Factor XIII deficiency in two Spanish families with a novel variant in gene F13A1 detected by next-generation sequencing; symptoms and clinical management.

Coagulation factor XIII (FXIII) has a major role in coagulation stabilizing the haemostatic clot. FXIII deficiency is associated with an increased risk of bleeding. Severe phenotypes lead to spontaneous, traumatic and surgical bleeding. Umbilical cord bleeding is especially common, and intracranial bleeding may occur in up to one third of patients without prophylaxis. In this work, we used NGS for screening all the coding and intronic boundary regions of F13A1 and F13B genes in two families affected by severe FXIII deficiency. Outcome confirmation analysis and variant studies in related patients was done by Sanger sequencing. Two variants were found: c.34A > G (p.Arg12Gly; NM_00129.3) and c.514C > T (p.Arg172Ter; NM_00129.3), both located in the F13A1 gene. The variant p.Arg172Ter is already described in literature and was found in homozygosis in one family and in compound heterozygosis in the other family. The variant p.Arg12Gly variant has not been described previously. This variant is located in the activation peptide of the FXIII A-subunit which is highly conserved among FXIII homologs. Given the high risk of dangerous bleeding and early manifestation in severe FXIII-deficient patients, a prompt genetic confirmation is imperative. In this sense, NGS technology allows a rapid and simultaneous analysis of all regions of all the genes involved in the pathology.

The changing face of immune tolerance induction in haemophilia A with the advent of emicizumab.

INTRODUCTION: As a result of the new treatment paradigm that the haemophilia community will face with the availability of novel (non-factor) therapies, an updated consensus on ITI recommendations and inhibitor management strategies is needed. AIM: The Future of Immunotolerance Treatment (FIT) group was established to contemplate, determine and recommend the best management options for patients with haemophilia A and inhibitors. DISCUSSION AND CONCLUSIONS: Despite the considerable success of emicizumab in the management of inhibitor patients, the FIT group still sees the importance of eradicating inhibitors. However, the availability of emicizumab and other non-factor therapies in the future might impact greatly on how ITI is undertaken. Theoretically, concomitant use of emicizumab and FVIII might allow emicizumab to effectively prevent bleeding with lower dose ITI regimens. This might allow for the greater adoption of low-dose/low-frequency FVIII ITI regimens, which may result in a reduced need for central venous access devices while still maintaining a reasonable likelihood of ITI success. The FIT group proposes a new management algorithm for current ITI (without emicizumab) and a hypothetical new approach with the availability of emicizumab. As there are no published data regarding the concomitant use of emicizumab and FVIII for ITI, the FIT Expert group encourages the undertaking of properly conducted prospective studies to explore these approaches further.

Factor VIII gene (F8) mutation and risk of inhibitor development in nonsevere hemophilia A.

Neutralizing antibodies (inhibitors) toward factor VIII form a severe complication in nonsevere hemophilia A, profoundly aggravating the bleeding pattern. Identification of high-risk patients is hampered by lack of data that take exposure days to therapeutic factor VIII concentrates into account. In the INSIGHT study, we analyzed the association between F8 mutation and inhibitor development in patients with nonsevere hemophilia A (factor VIII 2-40 IU/dL). This analysis included 1112 nonsevere hemophilia A patients from 14 centers in Europe and Australia that had genotyped at least 70% of their patients. Inhibitor risk was calculated as Kaplan-Meier incidence with cumulative number of exposure days as the time variable. During 44 800 exposure days (median, 24 exposure days per patient; interquartile range [IQR], 7-90), 59 of the 1112 patients developed an inhibitor; cumulative incidence of 5.3% (95% confidence interval [CI], 4.0-6.6) after a median of 28 exposure days (IQR, 12-71). The inhibitor risk at 50 exposure days was 6.7% (95% CI, 4.5-8.9) and at 100 exposure days the risk further increased to 13.3% (95% CI, 9.6-17.0). Among a total of 214 different F8 missense mutations 19 were associated with inhibitor development. These results emphasize the importance of F8 genotyping in nonsevere hemophilia A.

Clinical benefits of a Bayesian model for plasma-derived factor VIII/VWF after one year of pharmacokinetic-guided prophylaxis in severe/moderate hemophilia A patients.

INTRODUCTION: Individual pharmacokinetic (PK) profiling in hemophilia A (HA) helps to individualize prophylaxis using population PK models (popPK). A specific popPK model for plasma-derived factor VIII containing von-Willebrand Factor (pdFVIII/VWF) was developed. AIM: To compare standard versus PK-driven prophylaxis, using a generic or a specific popPK model for pdFVIII/VWF. MATERIALS AND METHODS: A prospective study conducted in HA patients in prophylaxis with pdFVIII/VWF (Fanhdi®) comparing three one-year study periods: (1) standard prophylaxis, (2) PK-guided prophylaxis using a generic pdFVIII popPK model which described FVIII activity irrespective of FVIII concentrate, and (3) PK-guided prophylaxis with specific pdFVIII/VWF popPK model. PK parameters analyzed were half-life, trough levels (TL) at 24, 48 and 72 h, and time to reach FVIII levels of 1, 2, 5% (T5%). Clinical outcomes were dose/kg, FVIII consumption, annualized bleeding rate (ABR), annualized joint bleeding rate (AJBR), spontaneous and traumatic bleeds. RESULTS: Of the 30 analyzed patients, 28 had severe HA and the median age was 31.2. Fifteen patient's prophylaxis doses were PK-adjusted. After the generic PK-guided prophylaxis period, younger patients showed more joint bleeds, a shorter half-life, and lower TL48, TL72 and T5%. Using the specific pdFVIII/VWF popPK model compared with standard prophylaxis, a lower spontaneous AJBR was observed in the entire cohort and in patients aged >15 years. Additionally, lower spontaneous ABR was reported in patients aged ≤15 years comparing specific and generic models. CONCLUSIONS: PK-guided prophylaxis with a specific pdFVIII/VWF popPK model allowed treatment individualization and improved bleeding control in routine clinical practice, especially in younger patients with short pdFVIII/VWF half-lives.

Management of acquired hemophilia A: results from the Spanish registry.

The Spanish Acquired Hemophilia A (AHA) Registry is intended to update the status of AHA in Spain. One hundred and fifty-four patients were included and retrospectively followed for a median of 12 months. Patients were predominantly male (56.3%), with median age at diagnosis of 74 years. AHA was more frequently idiopathic (44.1%) and autoimmune disorder-associated (31.7%). Thirty-four percent of patients were on antithrombotic therapy at diagnosis. Hemostatic treatment was used in 70% of patients. Recombinant activated factor VII was more frequently infused (60.3% vs 20.6% activated prothrombin complex concentrate). Only 1 patient did not achieve control of hemorrhage. Complete remission (CR) was achieved by 84.2% of cases after immunosuppressive therapy. Steroids alone were less efficient than the other strategies (68.2% vs 87.2%, P = .049), whereas no differences existed among these (steroids/cyclophosphamide, 88.5%, vs steroids/calcineurin inhibitors, 81.2%, vs rituximab-based regimens, 87.5%). Female sex and high inhibitor levels influenced CR negatively. Thirty-six deaths (23.8%) were reported. Main causes of death were infection (15 patients, 9.9%) and hemorrhage (5 patients, 3.3%). All hemorrhage-related and half the infection-related deaths occurred within 2 months of diagnosis. Prior antithrombotic therapy was inversely associated with survival, irrespective of age. Median age of nonsurvivors was significantly higher (79 vs 73 years in survivors). Patients dying of infection were older than the other nonsurvivors (85 vs 78 years). In summary, fatal infection in the first months is common in our series. Antithrombotic therapy is associated with mortality. Particular care should be taken to avoid misdiagnosis.

Novel missense mutation c.2685G>C (p.Q895H) in VWF gene associated with very low levels of VWF mRNA.

Homozygous patients for null alleles in VWF gene show a severe von Willebrand phenotype, whereas compound heterozygous patients only show the phenotype of the expressed allele. Five members of the same family were studied. The two patients showed borderline VWF levels, a mild factor VIII (FVIII) deficiency and a decrease of the binding of VWF to exogenous FVIII. The genetic analyses of the VWF gene confirmed that the patients were compound heterozygous for c.2561G>A (R854Q) and c.2685G>C (p.Q895H) mutations. The latter, is located in the 3' extreme of exon 20, and it has not been previously described. Studies of the cDNA from platelet mRNA were performed to investigate the expression of p.H895 allele. The loss of heterozygosity at the cDNA level suggests a lack of expression of the p.H895 allele. The overall studies can explain the type 2N phenotype of the two patients, since the allele carrying the new missense mutation p.Q895H has shown a low expression of VWF gene.

Prophylactic treatment in hemophilic patients with inhibitors.

: The development of inhibitors continues to be the most important complication in severe hemophilia A. The management of inhibitor patients revolves around two basic principles: eradication of the inhibitor and management and prevention of bleeding. In this paper, we review the prophylactic treatments carried out in the last two decades with the two available bypassing agents and the results of the clinical trials carried out with the new molecules under investigation or already licensed for the prevention of hemorrhagic episodes in hemophilia, like emicizumab.

Severe and moderate hemophilia A: identification of 38 new genetic alterations.

Hemophilia A is an X-linked recessive disorder caused by a lack or decrease of factor VIII activity. Its socio-economic impact is high given its high bleeding expression and treatment cost. Our aim was to establish the mutation of each patient to improve family management. A total of 116 unrelated families with severe and moderate hemophilia A were involved. Non-carriers of intron 22 and intron 1 rearrangements were included in F8 gene screening. Intron 1 and 22 inversion frequencies were 3% and 52.5% respectively. Putative mutations were identified in all the families; 38 were new. The cumulative inhibitor incidence was 22%. Approximately half the families carry non-recurrent mutations, which were unique in around one third. Harmful effects for mutations predicting null alleles are expected. Missense mutation consequences are not easily predictable, despite the help of some bio-informatics tools.

Allogeneic hematopoietic cell transplantation in an adult patient with Glanzmann thrombasthenia.

Glanzmann thrombasthenia is a rare bleeding disorder that can present life-threatening bleeding. Our patients develop antiplatelet antibodies that become refractory to any pharmacological treatment. Allogeneic hematopoietic stem-cell transplantation is the only currently curative procedure, but has major risks mainly in adult; indeed, our patient died.

Von Willebrand's disease: a novel mutation, P1824H and the incidence of R1205H defect among families with dominant quantitative von Willebrand factor deficiency.

To date, few mutations associated with a dominant quantitative deficiency of von Willebrand factor (VWF) and a high penetrance have been reported. This phenotype was confirmed in seven unrelated families of several patients diagnosed with von Willebrand's disease out of 70 who requested genetic studies of the VWF gene. The mutations linked to this type were identified: R1205H in five families; T1156M in one family; and the new P1824H alteration in one other family. The R1205H mutation linked to the different haplotypes might well be frequent among this variant. The P1824H in the A3 domain is associated with very low VWF levels and with a moderate-to-severe bleeding tendency, unlike the other mutations reported in this domain.

Identification of deletion carriers in hemophilia B: quantitative real-time polymerase chain reaction or multiple ligation probe amplification.

Gross deletions in the F9 gene are easily detected by routinely sequencing hemophilia B-affected men. Nevertheless, a carrier diagnosis proves difficult as the presence of a normal allele does not recognize the partial or complete loss of the F9 gene and may be challenging if no DNA sample from affected men is available. This work aimed to identify hemophilia carriers in 2 families in which gross deletions of the F9 gene could be expected. The indirect genetic study was not conclusive, and sequencing did not show genetic defects in family 1. A real-time polymerase chain reaction (RT-PCR) assay using SYBR Green revealed the deletion of a copy of exon 8 in 3 women, whereas the multiple ligation-dependent probe amplification (MLPA) assay showed the deletion of a copy of exons 7 and 8 in these 3 women. These studies enabled us not only to rule out a pregnant woman as a carrier but also to confirm a complete deletion of the gene in the patient from family 2 and the heterozygous state of his mother. The advantages that the MLPA method offers are the identification of a multiple exon deletion in the same assay and commonly used technology. The RT-PCR technology used involves standardizing and analyzing each exon independently.