Prevalence, biological phenotype and genotype in moderate/ mild hemophilia A with discrepancy between one-stage and chromogenic factor VIII activity

International audienceBackground: In most laboratories, the severity of hemophilia A is assessed by the factor VIII activity (FVIII:C) one-stage assay. However, comparisons of these results with those of two-stage assays can reveal discrepancies and suggest misdiagnosis. Patients/Methods: In this monocentric study, we measured FVIII:C with two methods (one-stage chronometric and chromogenic assays) in 307 (173 families) patients with moderate/mild hemophilia A. To compare results, we used a chronometric/chromogenic ratio. Discrepancy was defined as a ratio < 0.5 or > 1.5. We studied their putative involvement at known FVIII functional sites, their interspecies conservation status, and their spatial position within the FVIII structure. Results: Thirty-six patients from 17 families exhibited a discrepancy between the two assays: 12 (6.9%) families had a low ratio (< 0.5), and five (2.9%) families had a high ratio (> 1.5). Qualitative deficiency was diagnosed in about 16% of the families. Molecular studies were performed in 15 of these 17 families, resulting in each case in the identification of missense mutations, including three novel mutations. We were further able to propose a pathophysiologic explanation. Conclusions: In this monocentric study, we have demonstrated a discrepancy between FVIII:C assay results in 10% of families with moderate/mild hemophilia A. The prevalence of ÔinverseÕ discrepancy (i.e. low chronometric/chromogenic ratio) is high as compared with previous reports. We suggest that both FVIII:C assays are recommended in patients with moderate/mild hemophilia A for a complete biological phenotype. This could also improve our knowledge of the FVIII structure-function relationships

Reinvestigation of unidentified causative variants in FXI-deficient patients: Focus on gene segment deletions

International audienceIntroduction: Data on failure to identify the molecular mechanism underlying FXI deficiency by Sanger analysis and the contribution of gene segment deletions are almost inexistent. Aims and methods: Prospective and retrospective analysis was conducted on FXI-deficient patients’ DNA via Next Generation Sequencing (NGS), or Sanger sequencing and Multiplex Probe Ligation-dependent Assay (MLPA) to detect cryptic causative gene variants or gene segment deletions. Results: Sanger analysis or NGS enabled us to identify six severe and one partial (median activity 41 IU/dl) FXI deficient index cases with deletions encompassing exons 11–15, the whole gene, or both. After Sanger sequencing, retrospective evaluation using MLPA detected seven additional deletion cases in apparently homozygous cases in non-consanguineous families, or in previously unsolved FXI-deficiency cases. Among the 504 index cases with a complete genetic investigation (Sanger/MLPA, or NGS), 23 remained unsolved (no abnormality found [n = 14] or rare intronic variants currently under investigation, [n = 9]). In the 481 solved cases (95% efficiency), we identified F11 gene-deleted patients (14 cases; 2.9%). Among these, whole gene deletion accounted for four heterozygous cases, exons 11–15 deletion for five heterozygous and three homozygous ones, while compound heterozygous deletion and isolated exon 12 deletion accounted for one case each. Conclusion: Given the high incidence of deletions in our population (2.9%), MLPA (or NGS with a reliable bioinformatic pipeline) should be systematically performed for unsolved FXI deficiencies or apparently homozygous cases in non-consanguineous families

Biological, clinical features and modelling of heterozygous variants of glycoprotein Ib platelet subunit alpha (GP1BA) and glycoprotein Ib platelet subunit beta (GP1BB) genes responsible for constitutional thrombocytopenia

International audienceConstitutional thrombocytopenias are rare disorders, often difficult to discriminate from acquired thrombocytopenias. More than 80 genes have been described as being at the origin of these diseases. Among them, several variants of the glycoprotein Ib platelet subunit alpha (GP1BA) and glycoprotein Ib platelet subunit beta (GP1BB) genes, coding for the GpIb-IX-V glycoprotein complex, have been reported in the literature. The study reported here aimed at describing newly identified monoallelic anomalies affecting the GP1BA and GP1BB genes on a clinical, biological and molecular level. In a cohort of nine patients with macrothrombocytopenia, eight heterozygous variants of the GP1BA or GP1BB genes were identified. Five of them had never been described in the heterozygous state. Computer modelling disclosed structure/function relationships of these five variants

Two novel variants of uncertain significance in GP9 associated with Bernard–Soulier syndrome: Are they true mutations?

International audienceBernard–Soulier syndrome (BSS) is an autosomal recessive major thrombocytopathy, the symptoms of which are mainly marked by mucocutaneous bleeding. This rare disease, initially described in the 1970s, is the result of an abnormal formation of the glycoprotein complex Ib-IX-V (GP Ib-IX-V), a platelet receptor of von Willebrand factor. A large number of mutations, sometimes involving the GP9 gene, have been described as possibly responsible for the disease. We report here the case of a BSS patient who presented with persistent thrombocytopenia (31x10[9]/L) and decreased surface expression of GPIb-IX-V on large platelets with anisocytosis. Thorough molecular analyses disclosed two previously unreported GP9 variants, respectively c.230T>A (p.Leu77Gln) and c.255C>A (p.Asn85Lys). Both are likely to modify the conformation of GP-IX interactions with other glycoproteins of the Ib-IX-V complex and thus proper expression of this complex on the membrane of platelets

Prostate interventions in patients with mild haemophilia: Safe and feasible

International audienceIntroduction: To date, there is no specific recommendation or evaluation of the morbidity of prostate surgery in patients with haemophilia (PWH) although this surgery is common and at high risk of bleeding.Aim: To assess the post-operative morbidity of benign prostate hyperplasia (BPH) surgeries and of oncological prostate interventions in patients with mild haemophilia A or B.Methods: We performed a monocentre, epidemiological, in real life study. Data were collected between 1 January, 1997 and 1 September, 2020 and focused on prostate biopsy, radical prostatectomy, prostate radiotherapy, simple prostatectomy, transurethral resection of prostate (TURP) and laser-vaporisation in patients with mild haemophilia A or B.Results: Between 1 January, 1997 and 1 September, 2020, 51 interventions were performed on 30 patients with mild haemophilia. Haemophilia A represented 93.33% of the population and haemophilia B 6.67%. For prostate biopsies (n = 24), median length of hospitalisation was 4 days and only one patient needed a blood transfusion. No patient needed re-admission. For prostatectomy (n = 10), one patient presented with intra-operative and post-operative bleeding. Two patients required re-admission. The other patients did not present any significant haemorrhagic symptoms. For radiotherapy (n = 4), two patients presented a grade II complication (radiocystitis and radiorectitis). For BPH surgeries, during hospitalisation, laser-vaporisation (n = 5) was less haemorrhagic than TURP (n = 5) but after hospital discharge, 60% of patients presented a haemorrhagic complication with two readmissions and one surgical re-explorations.Conclusion: Performed in a specialised centre, prostate surgeries and interventions in patients with mild haemophilia is feasible with acceptable morbidity

Simoctocog alfa (Nuwiq®) in previously untreated patients with severe haemophilia A—Final efficacy and safety results from the NuProtect study

Introduction: Simoctocog alfa (Nuwiq®) is a 4th generation recombinant FVIII with proven efficacy for the prevention and treatment of bleeding episodes (BEs) in previously treated patients with severe haemophilia A. The NuProtect study assessed the immunogenicity, efficacy and safety of simoctocog alfa in 108 previously untreated patients (PUPs). The incidence of high-titre inhibitors was 16.2% and no patients with non-null F8 mutations developed inhibitors.Aim: To report the efficacy and safety results from the NuProtect study.Methods: PUPs received simoctocog alfa for prophylaxis, treatment of BEs, or as surgical prophylaxis. The efficacy of prophylaxis (during inhibitor-free periods) was assessed using annualised bleeding rates (ABRs). The efficacy in treating BEs and in surgical prophylaxis was assessed using a 4-point scale. Adverse events were recorded throughout the study.Results: Of 108 PUPs treated with simoctocog alfa, 103 received at least one prophylactic dose and 50 received continuous prophylaxis for at least 24 weeks. In patients on continuous prophylaxis, the median ABR was 0 (mean 0.5) for spontaneous BEs and 2.5 (mean 3.6) for all BEs. In 85 patients who had BEs, efficacy of BE treatment was excellent or good for 92.9% (747/804) of rated BEs; 92.3% of BEs were treated with 1 or 2 infusions. The efficacy of surgical prophylaxis was excellent or good for 94.7% (18/19) of rated procedures. There were no safety concerns and no thromboembolic events.Conclusion: Simoctocog alfa was efficacious and well tolerated as prophylaxis, surgical prophylaxis and for the treatment of BEs in PUPs with severe haemophilia A

Simoctocog alfa (Nuwiq®) in previously untreated patients with severe haemophilia A-Final efficacy and safety results from the NuProtect study.

Funder: Octapharma; doi: http://dx.doi.org/10.13039/501100016300INTRODUCTION: Simoctocog alfa (Nuwiq®) is a 4th generation recombinant FVIII with proven efficacy for the prevention and treatment of bleeding episodes (BEs) in previously treated patients with severe haemophilia A. The NuProtect study assessed the immunogenicity, efficacy and safety of simoctocog alfa in 108 previously untreated patients (PUPs). The incidence of high-titre inhibitors was 16.2% and no patients with non-null F8 mutations developed inhibitors. AIM: To report the efficacy and safety results from the NuProtect study. METHODS: PUPs received simoctocog alfa for prophylaxis, treatment of BEs, or as surgical prophylaxis. The efficacy of prophylaxis (during inhibitor-free periods) was assessed using annualised bleeding rates (ABRs). The efficacy in treating BEs and in surgical prophylaxis was assessed using a 4-point scale. Adverse events were recorded throughout the study. RESULTS: Of 108 PUPs treated with simoctocog alfa, 103 received at least one prophylactic dose and 50 received continuous prophylaxis for at least 24 weeks. In patients on continuous prophylaxis, the median ABR was 0 (mean 0.5) for spontaneous BEs and 2.5 (mean 3.6) for all BEs. In 85 patients who had BEs, efficacy of BE treatment was excellent or good for 92.9% (747/804) of rated BEs; 92.3% of BEs were treated with 1 or 2 infusions. The efficacy of surgical prophylaxis was excellent or good for 94.7% (18/19) of rated procedures. There were no safety concerns and no thromboembolic events. CONCLUSION: Simoctocog alfa was efficacious and well tolerated as prophylaxis, surgical prophylaxis and for the treatment of BEs in PUPs with severe haemophilia A