Introduction
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.
Despite a high prevalence of angiodysplasia, no specific guidelines are available for the modalities of endoscopic exploration of gastrointestinal (GI) bleeding in von Willebrand disease (VWD). ...Whether VWD patients could benefit from video capsule endoscopy (VCE) looking for angiodysplasia eligible to endoscopic treatment or at high risk of bleeding is unknown.
To assess the diagnostic efficacy for angiodysplasia and the prognostic value of VCE on top of conventional endoscopy in VWD patients with GI bleeding.
A survey was sent to the 30 centers of the French-network on inherited bleeding disorders to identify VWD patients referred for endoscopic exploration of GI bleeding from January 2015 to December 2017. Data obtained included patient characteristics, VWD phenotype/genotype, GI bleeding pattern, results of endoscopic investigations, and medical management applied including endoscopic therapy. We assessed by Kaplan-Meier analysis the recurrence-free survival after the first GI bleeding event according to endoscopic categorization and, in patients with angiodysplasia, to the presence of small-bowel localizations on VCE exploration.
GI bleeding source localization was significantly improved when including VCE exploration (P < .01), even in patients without history of angiodysplasia (P < .05). Patients with angiodysplasia had more GI bleeding recurrences (P < .01). A lower recurrence-free survival was observed in patients with angiodysplasia (log-rank test, P = .02), and especially when lesions were located in the small bowel (log-rank test, P < .01), even after endoscopic treatment with argon plasma coagulation (log-rank test, P < .01).
VCE should be more systematically used in VWD patients with unexplained or recurrent GI bleeding looking for angiodysplasia eligible to endoscopic treatment or at high risk of relapse.
Adeno-associated virus (AAV)-mediated gene therapy may provide durable protection from bleeding events and reduce treatment burden for people with hemophilia A (HA). However, pre-existing immunity ...against AAV may limit transduction efficiency and hence treatment success. Global data on the prevalence of AAV serotypes are limited. In this global, prospective, noninterventional study, we determined the prevalence of pre-existing immunity against AAV2, AAV5, AAV6, AAV8, and AAVrh10 among people ≥12 years of age with HA and residual FVIII levels ≤2 IU/dL. Antibodies against each serotype were detected using validated, electrochemiluminescent-based enzyme-linked immunosorbent assays. To evaluate changes in antibody titers over time, 20% of participants were retested at 3 and 6 months. In total, 546 participants with HA were enrolled at 19 sites in 9 countries. Mean (standard deviation) age at enrollment was 36.0 (14.87) years, including 12.5% younger than 18 years, and 20.0% 50 years of age and older. On day 1, global seroprevalence was 58.5% for AAV2, 34.8% for AAV5, 48.7% for AAV6, 45.6% for AAV8, and 46.0% for AAVrh10. Considerable geographic variability was observed in the prevalence of pre-existing antibodies against each serotype, but AAV5 consistently had the lowest seroprevalence across the countries studied. AAV5 seropositivity rates were 51.8% in South Africa (
= 56), 46.2% in Russia (
= 91), 40% in Italy (
= 20), 37.2% in France (
= 86), 26.8% in the United States (
= 71), 26.9% in Brazil (
= 26), 28.1% in Germany (
= 89), 29.8% in Japan (
= 84), and 5.9% in the United Kingdom (
= 17). For all serotypes, seropositivity tended to increase with age. Serostatus and antibody titer were generally stable over the 6-month sampling period. As clinical trials of AAV-mediated gene therapies progress, data on the natural prevalence of antibodies against various AAV serotypes may become increasingly important.
Introduction
Factor X deficiency is a rare inherited bleeding disorder. To date, 181 variants are reported in the recently updated F10‐gene variant database.
Aim
This study aimed to describe new F10 ...variants.
Method
The F10 gene was analysed in 16 consecutive families with FX deficiency by a targeted high‐throughput sequencing approach, including F10, F9, F8 genes, and 78 genes dedicated to haematological malignancies.
Results
We identified 19 variants (17 missense, one nonsense and one frameshift) and two copy number variations. Two patients presenting a combined FVII‐FX deficiency showed a loss of one F10 gene copy (del13q34) associated with a missense variant on the remaining allele, leading to a FX:C significantly lower than the FVII:C level and explaining their unusual bleeding history. We reported five novel variants. Three missense variants (p.Glu22Val affecting the signal peptide cleavage site, p.Cys342Tyr removing the disulphide bond between the FX heavy and light chains, and p.Val385Met located in FX peptidase S1 domain) were detected at compound heterozygosis status in three patients with severe bleeding symptoms and FX:C level below 10 IU/dL. Two truncating variants p.Tyr279* and p.Thr434Aspfs*13 leading to an altered FX protein were found at heterozygous state in two patients with mild bleeding history.
Conclusion
This study showed the feasibility and the interest of high‐throughput sequencing approach for rare bleeding disorders, enabling the report of F10 gene screening in a 3‐weeks delay, suitable for clinical use. The description of five new variants may contribute to a better understanding of the phenotype‐genotype correlation in FX deficiency.
Introduction: Over the last decades, life expectancy of patients with hemophilia (PWH) has significantly improved and therefore, age-related comorbidities like cardiovascular disease (CVD) are now ...common features. Using antithrombotic and antiplatelet agents, as needed for managing CVD, proves complex in PWH given that these drugs, along with the often required invasive procedures, interfere with hemostasis; general recommendations are not applicable as such.
Method: To collect data on current real-life practices in this patient population, the COCHE registry (COmorbidités Cardiovasculaires chez les patients HEmophiles) has been implemented back in July 2011. This French observational study sought to describe prospectively the management of CVD in PWH who require treatment with antiplatelet agents, antithrombotics, or both.
Results: By January 2018, this registry had prospectively included 67 PWH: 59 hemophilia A and 8 hemophilia B patients (47 mild, 10 moderate, and 10 severe), with a median age of 65±12.5 years. Overall, 52 patients were included for coronary artery disease (CAD) and 16 for atrial fibrillation (AF), with one patient presenting both CAD and AF. Among the 67 patients enrolled, 49 were receiving on-demand replacement therapy. Identified cardiovascular risk factors were arterial hypertension (n=44), overweight or obesity (n= 35), dyslipidemia (n=30; four tested positive for human immune deficiency virus HIV), smoking (n=17), family coronary disease history (n=11), non-insulin dependent diabetes mellitus (NIDDM) (n=11), and insulin dependent diabetes mellitus (IDDM) (n=3).
Conclusion: The proposals discussed herein are largely based on the experience we gained whilst managing PWH with CVD from the COCHE registry. To us, a multidisciplinary approach appears paramount.
Lebreton:Sobi: Consultancy, Research Funding.
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