Molecular and clinical profile of von Willebrand disease in Spain (PCM-EVW-ES): comprehensive genetic analysis by next-generation sequencing of 480 patients.

Molecular diagnosis of patients with von Willebrand disease is pending in most populations due to the complexity and high cost of conventional molecular analyses. The need for molecular and clinical characterization of von Willebrand disease in Spain prompted the creation of a multicenter project (PCM-EVW-ES) that resulted in the largest prospective cohort study of patients with all types of von Willebrand disease. Molecular analysis of relevant regions of the VWF, including intronic and promoter regions, was achieved in the 556 individuals recruited via the development of a simple, innovative, relatively low-cost protocol based on microfluidic technology and next-generation sequencing. A total of 704 variants (237 different) were identified along VWF, 155 of which had not been previously recorded in the international mutation database. The potential pathogenic effect of these variants was assessed by in silico analysis. Furthermore, four short tandem repeats were analyzed in order to evaluate the ancestral origin of recurrent mutations. The outcome of genetic analysis allowed for the reclassification of 110 patients, identification of 37 asymptomatic carriers (important for genetic counseling) and re-inclusion of 43 patients previously excluded by phenotyping results. In total, 480 patients were definitively diagnosed. Candidate mutations were identified in all patients except 13 type 1 von Willebrand disease, yielding a high genotype-phenotype correlation. Our data reinforce the capital importance and usefulness of genetics in von Willebrand disease diagnostics. The progressive implementation of molecular study as the first-line test for routine diagnosis of this condition will lead to increasingly more personalized and effective care for this patient population.

Application of a molecular diagnostic algorithm for haemophilia A and B using next-generation sequencing of entire F8, F9 and VWF genes.

Currently, molecular diagnosis of haemophilia A and B (HA and HB) highlights the excess risk-inhibitor development associated with specific mutations, and enables carrier testing of female relatives and prenatal or preimplantation genetic diagnosis. Molecular testing for HA also helps distinguish it from von Willebrand disease (VWD). Next-generation sequencing (NGS) allows simultaneous investigation of several complete genes, even though they may span very extensive regions. This study aimed to evaluate the usefulness of a molecular algorithm employing an NGS approach for sequencing the complete F8, F9 and VWF genes. The proposed algorithm includes the detection of inversions of introns 1 and 22, an NGS custom panel (the entire F8, F9 and VWF genes), and multiplex ligation-dependent probe amplification (MLPA) analysis. A total of 102 samples (97 FVIII- and FIX-deficient patients, and five female carriers) were studied. IVS-22 screening identified 11 out of 20 severe HA patients and one female carrier. IVS-1 analysis did not reveal any alterations. The NGS approach gave positive results in 88 cases, allowing the differential diagnosis of mild/moderate HA and VWD in eight cases. MLPA confirmed one large exon deletion. Only one case did have no pathogenic variants. The proposed algorithm had an overall success rate of 99 %. In conclusion, our evaluation demonstrates that this algorithm can reliably identify pathogenic variants and diagnose patients with HA, HB or VWD.

Molecular and clinical profile of von Willebrand disease in Spain (PCM-EVW-ES): Proposal for a new diagnostic paradigm.

The diagnosis of von Willebrand disease (VWD) remains difficult in a significant proportion of patients. A Spanish multicentre study investigated a cohort of 556 patients from 330 families who were analysed centrally. VWD was confirmed in 480. Next generation sequencing (NGS) of the whole coding VWF was carried out in all recruited patients, compared with the phenotype, and a final diagnosis established. A total of 238 different VWF mutations were found, 154 were not included in the Leiden Open Variation Database (LOVD). Of the patients, 463 were found to have VWF mutation/s. A good phenotypic/genotypic association was estimated in 96.5% of the patients. One hundred seventy-four patients had two or more mutations. Occasionally a predominant phenotype masked the presence of a second abnormality. One hundred sixteen patients presented with mutations that had previously been associated with increased von Willebrand factor (VWF) clearance. RIPA unavailability, central phenotypic results disagreement and difficult distinction between severe type 1 and type 3 VWD prevented a clear diagnosis in 70 patients. The NGS study facilitated an appropriate classification in 63 of them. The remaining seven patients presented with a VWF novel mutation pending further investigation. In five patients with a type 3 and two with a type 2A or 2B phenotype with no mutation, an acquired von Willebrand syndrome (AVWS) was suspected/confirmed. These data seem to support NGS as a first line efficient and faster paradigm in VWD diagnosis.

Tratamiento de la hemoglobinuria paroxística nocturna con eculizumab: experiencia en España / Paroxysmal nocturnal hemoglobinuria therapy with eculizumab: Spanish experience

Fundamento y objetivo: La hemoglobinuria paroxística nocturna es una enfermedad clonal adquirida caracterizada por hemólisis mediada por complemento, insuficiencia medular y enfermedad tromboembólica. El eculizumab es un anticuerpo monoclonal dirigido contra la fracción C5 del complemento, que bloquea la formación del componente citolítico de este.Pacientes y método: Se estudian 25 pacientes en tratamiento con eculizumab en España. El análisis estadístico se realiza con el software SPSS v15.0. Resultados:Con una mediana de seguimiento de 14 meses (extremos 3-46), el eculizumab ha conseguido independencia transfusional en 58% de los pacientes y disminución del 60% de los requerimientos transfusionales en el resto de los pacientes, desaparición de la astenia en 96% de los casos y de los síntomas de distonía de músculo liso en la totalidad. Sólo un paciente ha presentado infección grave relacionada con el tratamiento.Conclusiones: El tratamiento con eculizumab es eficaz en el control de la hemólisis, con gran mejoría clínica. El fármaco es seguro y bien tolerado, sin efectos secundarios significativos, salvo el riesgo de infección meningocócica. En pacientes con respuesta subóptima a eculizumab es preciso valorar el grado de insuficiencia medular y la posibilidad de hemólisis extravascular (AU)

Background and objectives: Paroxysmal nocturnal hemoglobinuria (PNH) is a rare acquired clonal disease characterized by complement-mediated hemolysis, bone marrow failure and thrombosis. Eculizumab is a humanized monoclonal antibody that blocks the cytolytic component of the complement system by binding to complement C5. Material and Methods: We report the results of eculizumab treatment in 25 PNH patients from different centers in Spain. Statistical analysis was perfomed with a SPSS v15.0 software.Results: Fifty-eight per cent of the patients achieved transfusional independence after a median of 14 months. Transfusion requirements were reduced in 60% of the remaining cases. Fatigue resolved in 96% of the patients and smooth muscle dystony-related symptoms in all cases. A single case of treatment-related infection was observed. Conclusions: Eculizumab controls effectively hemolysis and greatly improves clinical symptoms. The drug is safe and well tolerated, without significant adverse effects except meningococcal infection. Patients with suboptimal response to treatment must be assessed for bone marrow insufficiency and extravascular haemolysis (AU)

[Paroxysmal nocturnal hemoglobinuria therapy with eculizumab: Spanish experience]. / Tratamiento de la hemoglobinuria paroxística nocturna con eculizumab: experiencia en España.

BACKGROUND AND OBJECTIVES: Paroxysmal nocturnal hemoglobinuria (PNH) is a rare acquired clonal disease characterized by complement-mediated hemolysis, bone marrow failure and thrombosis. Eculizumab is a humanized monoclonal antibody that blocks the cytolytic component of the complement system by binding to complement C5. MATERIAL AND METHODS: We report the results of eculizumab treatment in 25 PNH patients from different centers in Spain. Statistical analysis was perfomed with a SPSS v15.0 software. RESULTS: Fifty-eight per cent of the patients achieved transfusional independence after a median of 14 months. Transfusion requirements were reduced in 60% of the remaining cases. Fatigue resolved in 96% of the patients and smooth muscle dystony-related symptoms in all cases. A single case of treatment-related infection was observed. CONCLUSIONS: Eculizumab controls effectively hemolysis and greatly improves clinical symptoms. The drug is safe and well tolerated, without significant adverse effects except meningococcal infection. Patients with suboptimal response to treatment must be assessed for bone marrow insufficiency and extravascular haemolysis.