Expanding the genetic spectrum of TUBB1-related thrombocytopenia.

ß1-Tubulin plays a major role in proplatelet formation and platelet shape maintenance, and pathogenic variants in TUBB1 lead to thrombocytopenia and platelet anisocytosis (TUBB1-RT). To date, the reported number of pedigrees with TUBB1-RT and of rare TUBB1 variants with experimental demonstration of pathogenicity is limited. Here, we report 9 unrelated families presenting with thrombocytopenia carrying 6 ß1-tubulin variants, p.Cys12LeufsTer12, p.Thr107Pro, p.Gln423*, p.Arg359Trp, p.Gly109Glu, and p.Gly269Asp, the last of which novel. Segregation studies showed incomplete penetrance of these variants for platelet traits. Indeed, most carriers showed macrothrombocytopenia, some only increased platelet size, and a minority had no abnormalities. Moreover, only homozygous carriers of the p.Gly109Glu variant displayed macrothrombocytopenia, highlighting the importance of allele burden in the phenotypic expression of TUBB1-RT. The p.Arg359Trp, p.Gly269Asp, and p.Gly109Glu variants deranged ß1-tubulin incorporation into the microtubular marginal ring in platelets but had a negligible effect on platelet activation, secretion, or spreading, suggesting that ß1-tubulin is dispensable for these processes. Transfection of TUBB1 missense variants in CHO cells altered ß1-tubulin incorporation into the microtubular network. In addition, TUBB1 variants markedly impaired proplatelet formation from peripheral blood CD34+ cell-derived megakaryocytes. Our study, using in vitro modeling, molecular characterization, and clinical investigations provides a deeper insight into the pathogenicity of rare TUBB1 variants. These novel data expand the genetic spectrum of TUBB1-RT and highlight a remarkable heterogeneity in its clinical presentation, indicating that allelic burden or combination with other genetic or environmental factors modulate the phenotypic impact of rare TUBB1 variants.

A decade of changes in management of immune thrombocytopenia, with special focus on elderly patients.

BACKGROUND: Ten years after their availability, thrombopoietin receptor agonists (TPO-RA) have heralded a paradigm shift in the treatment of immune thrombocytopenia (ITP). This study was aimed to analyze the implementation of current recommendations in the standard practice of adult ITP patients, and how age may influence those changes. METHODS: We included 121 adult patients (> 65 years, n = 54; younger individuals, n = 67) who initiated treatment with TPO-RA between January 2012 and December 2014. RESULTS: Patients older than 65 years treated with TPO-RA presented at diagnosis with significantly higher platelet counts, less bleeding, and a more prothrombotic profile than younger ones. The high efficacy rates of TPO-RA, preferentially used during the last decade in non-chronic phases, precluded from further therapies in the majority of ITP patients. Their administration was associated with a sharp decline in the last decade in the use of splenectomy and intravenous immunoglobulin, especially in younger ITP individuals. CONCLUSION: These results confirm (1) that there is a preferential use of TPO-RAs in elderly ITP patients with fewer bleeding complications but more unfavorable prothrombotic conditions than in younger individuals, and (2) that early use of these agents has been established as an effective therapeutic alternative to other second line therapies.

Deciphering predictive factors for choice of thrombopoietin receptor agonist, treatment free responses, and thrombotic events in immune thrombocytopenia.

Very few data exist on when a particular thrombopoietin-receptor agonist (TPO-RA) is favored in clinical practice for the treatment of patients with immune thrombocytopenia (ITP), about novel risk factors for vascular events (VE) with these drugs, nor about predictive factors for therapy free responses (TFR). We conducted an observational, retrospective, long-term follow-up multicenter study from November 2016 to January 2018 of 121 adult ITP patients initiating TPO-RA between January 2012 to December 2014. Data reflected that a platelet count ≤25 × 109/l at the time when the TPO-RA was initiated was associated with a 2.8 higher probability of receiving romiplostim vs. eltrombopag (P = 0.010). VE on TPO-RA was related to previous neoplasia in patients over 65 years (50% vs. 2.2%, P < 0.001), and to previous splenectomy in younger patients (100% vs. 33%, P = 0.001). Receiving romiplostim as first TPO-RA with no subsequent TPO-RA switching was associated with a 50% likelihood of TFR after 2.9 years of therapy (3.3 years in chronic ITP patients). These real-world data help deciphering some areas of uncertainty, and offer insight into some of the most relevant challenges of ITP which may help clinicians make appropriate treatment decisions in the management of adult ITP patients with TPO-RA.

Identification of 58 Mutations (26 Novel) in 94 of 109 Symptomatic Spanish Probands with Protein C Deficiency.

Presently, no data on the molecular basis of hereditary protein C (PC) deficiency in Spain is available. We analyzed the PC gene (PROC) in 109 patients with symptomatic PC deficiency and in 342 relatives by sequencing the 9 PROC exons and their flanking intron regions. In 93 probands, we found 58 different mutations (26 novel). Thirty-seven consisted of a nucleotide change, mainly missense mutations, 1 was a 6-nucleotide insertion causing the duplication of 2 amino acids, and 4 were deletions of 1, 3, 4, and 16 nucleotides. Nine mutations caused type II deficiencies, with the presence of normal antigen levels but reduced anticoagulant activity. Using a PC level of 70% as lowest normal limit, we found no mutations in 16 probands and 25 relatives with PC levels ≤ 70%. On the contrary, 4 probands and 12 relatives with PC levels > 70% carried the mutation identified in the proband. The spectrum of recurrent mutations in Spain is different from that found in the Netherlands, where the most frequent mutations were p.Gln174* and p.Arg272Cys, and is more similar to that found in France, where the most frequent were p.Arg220Gln and p.Pro210Leu. In our study, p.Val339Met (9 families), p.Tyr166Cys (7), p.Arg220Gln (6), and p.Glu58Lys (5) were the most prevalent. This study confirms the considerable heterogeneity of the genetic abnormality in PC deficiencies, and allowed genetic counseling to those individuals whose PC levels were close to the lower limit of the normal reference range.

Involvement of antifactor VIII autoantibodies specificity in the outcome of inhibitor eradication therapies in acquired hemophilia a patients.

: We hypothesized that inhibitor specificity may predict the outcome of antifactor VIII autoantibodies eradication treatment in acquired hemophilia A. Our objective was to analyze the association between factor VIII domains recognized by inhibitors and outcome of the immunosuppressive therapies (ISTs) in a prospective, observational study. 16 patients were recruited. Inhibitor specificities were assessed at diagnosis and throughout the study. Their association with IST outcome was addressed. First-line IST succeeded in 56% of patients. Inhibitors reacted mainly with light chain domains (69%) and/or the A2 domain (44%). 31% inhibitors recognized more than one domain. Significantly, the number of patients whose inhibitors recognized the light chain was significantly higher in the group of those who did not reach complete remission after first line IST when compared with those who did [6/7 (85.7%) vs. 4/9 (44.4%), P < 0.05]. Therefore, inhibitor specificity could predict the success of IST in acquired hemophilia A.

Introducing high-throughput sequencing into mainstream genetic diagnosis practice in inherited platelet disorders.

Inherited platelet disorders are a heterogeneous group of rare diseases, caused by inherited defects in platelet production and/or function. Their genetic diagnosis would benefit clinical care, prognosis and preventative treatments. Until recently, this diagnosis has usually been performed via Sanger sequencing of a limited number of candidate genes. High-throughput sequencing is revolutionizing the genetic diagnosis of diseases, including bleeding disorders. We have designed a novel high-throughput sequencing platform to investigate the unknown molecular pathology in a cohort of 82 patients with inherited platelet disorders. Thirty-four (41.5%) patients presented with a phenotype strongly indicative of a particular type of platelet disorder. The other patients had clinical bleeding indicative of platelet dysfunction, but with no identifiable features. The high-throughput sequencing test enabled a molecular diagnosis in 70% of these patients. This sensitivity increased to 90% among patients suspected of having a defined platelet disorder. We found 57 different candidate variants in 28 genes, of which 70% had not previously been described. Following consensus guidelines, we qualified 68.4% and 26.3% of the candidate variants as being pathogenic and likely pathogenic, respectively. In addition to establishing definitive diagnoses of well-known inherited platelet disorders, high-throughput sequencing also identified rarer disorders such as sitosterolemia, filamin and actinin deficiencies, and G protein-coupled receptor defects. This included disease-causing variants in DIAPH1 (n=2) and RASGRP2 (n=3). Our study reinforces the feasibility of introducing high-throughput sequencing technology into the mainstream laboratory for the genetic diagnostic practice in inherited platelet disorders.

Remission and platelet responses with romiplostim in primary immune thrombocytopenia: final results from a phase 2 study.

In anecdotal reports, some patients with immune thrombocytopenia (ITP) maintained platelet counts after discontinuing romiplostim. Here, we examined rates of platelet response (≥50 × 10(9) /l), remission, splenectomy and adverse events in patients with primary ITP duration ≤6 months who were treated with romiplostim for ≤12 months. The starting dose of romiplostim was 1 µg/kg; concomitant and rescue treatments were permitted to maintain platelet counts. Patients with platelet counts ≥50 × 10(9) /l at the end of 12 months entered a dose taper in which the romiplostim dose was decreased as long as platelet counts were maintained. Remission (platelet count ≥50 × 10(9) /l for 24 consecutive weeks with no ITP treatments) was evaluated in patients once romiplostim was discontinued. Over the 12 months, a high response rate (>90%) was observed. Platelet response occurred quickly (median, ~2 weeks) and was observed for a cumulative median of 11 months. Remission was observed in 24 patients (32%); there were no significantly predictors of remission. Most (20/24) patients had remission start before the forced taper. No new safety signals were identified. Thus, in patients with early-stage ITP, romiplostim was well tolerated and induced rapid responses, with remission occurring in approximately one-third of patients (NCT01143038, Amgen 20080435).

Functional and molecular characterization of inherited platelet disorders in the Iberian Peninsula: results from a collaborative study.

BACKGROUND: The diagnostic evaluation of inherited platelet disorders (IPDs) is complicated and time-consuming, resulting in a relevant number of undiagnosed and incorrectly classified patients. In order to evaluate the spectrum of IPDs in individuals with clinical suspicion of these disorders, and to provide a diagnostic tool to centers not having access to specific platelets studies, we established the project "Functional and Molecular Characterization of Patients with Inherited Platelet Disorders" under the scientific sponsorship of the Spanish Society of Thrombosis and Haemostasis. PATIENTS/METHODS: Subjects were patients from a prospective cohort of individuals referred for clinical suspicion of IPDs as well as healthy controls. Functional studies included light transmission aggregation, flow cytometry, and when indicated, Western-blot analysis of platelet glycoproteins, and clot retraction analysis. Genetic analysis was mainly performed by sequencing of coding regions and proximal regulatory regions of the genes of interest. RESULTS: Of the 70 cases referred for study, we functionally and molecularly characterized 12 patients with Glanzmann Thrombasthenia, 8 patients with Bernard Soulier syndrome, and 8 with other forms of IPDs. Twelve novel mutations were identified among these patients. The systematic study of patients revealed that almost one-third of patients had been previously misdiagnosed. CONCLUSIONS: Our study provides a global picture of the current limitations and access to the diagnosis of IPDs, identifies and confirms new genetic variants that cause these disorders, and emphasizes the need of creating reference centers that can help health care providers in the recognition of these defects.

Acquired von Willebrand syndrome and mitral valve prosthesis leakage. A pilot study.

BACKGROUND: Of patients with severe aortic stenosis, 15-25% present with bleeding episodes possibly attributable to acquired von Willebrand syndrome (AVWS). AVWS associated with mitral valve prosthesis leakage has not been reported. METHODS AND RESULTS: Five patients receiving appropriate oral anticoagulation showed mitral valve prosthesis leakage and bleeding episodes; all of them required hospitalization and two blood transfusions, and a von Willebrand factor (VWF) analysis was performed. Two patients with normal functioning metallic prosthesis valves were included as controls. Before surgery, after cessation of acenocumarol, the patients had prolonged activated partial thromboplastin time; four had prolonged closure time (CT) from the platelet function analyzer. Factor VIII procoagulant activity (FVIII:C), VWF ristocetin cofactor activity (VWF:RCo), and VWF collagen binding (VWF:CB) were considerably elevated, while VWF antigen (VWF:Ag) was most elevated. Disproportionate VWF:RCo/VWF:Ag and VWF:CB/VWF:Ag ratios were seen with the loss of large VWF multimers. Following surgery, all parameters were markedly increased and the ratios, CT, and multimeric VWF profile became normal. CONCLUSIONS: Acquired VWF qualitative alterations in mitral valve prosthesis leakage may be associated with or contribute to bleeding diathesis. AVWS should be taken into consideration in patients with mitral valve prosthesis leakage with bleeding diathesis not explained by excessive oral anticoagulation.

[The "Seville" Consensus Document on Alternatives to Allogenic Blood Transfusion. Sociedades españolas de Anestesiología (SEDAR), Medicina Intensiva (SEMICYUC), Hematología y Hemoterapia (AEHH), Transfusión sanguínea (SETS) Trombosis y Hemostasia (SETH)]. / Documento «Sevilla¼ de Consenso sobre Alternativas a la Transfusión de Sangre Alogénica.

The Consensus Document on Alternatives to Allogenic Blood Transfusion (AABT) has been drawn up by a panel of experts from 5 scientific societies. The Spanish Societies of Anesthesiology (SEDAR), Critical Care Medicine and Coronary Units (SEMICYUC), Hematology and Hemotherapy (AEHH), Blood Transfusion (SETS) and Thrombosis and Hemostasis (SETH) have sponsored and participated in this Consensus Document. Alternatives to blood transfusion have been divided into pharmacological and non-pharmacological, with 4 modules and 12 topics. The main objective variable was the reduction of allogenic blood transfusions and/or the number of transfused patients. The extent to which this objective was achieved by each AABT was evaluated using the Delphi method, which classifies the grade of recommendation from A (supported by controlled studies) to E (non-controlled studies and expert opinion). The experts concluded that most of the indications for AABT were based on middle or low grades of recommendation, "C", "D", or "E", thus indicating the need for further controlled studies.

Documento «Sevilla» de Consenso sobre Alternativas a la Transfusión de Sangre Alogénica / The «Seville» Consensus Document on Alternatives to Allogenic Blood Transfusion

El Documento de Consenso sobre Alternativas a la Transfusión de Sangre Alogénica (ATSA) ha sido elaborado por un panel de expertos pertenecientes a 5 sociedades científicas. Han participado y patrocinado las sociedades españolas de Anestesiología (SEDAR), Medicina Intensiva (SEMICYUC), Hematología y Hemoterapia (AEHH), Transfusión sanguínea (SETS) y Trombosis y Hemostasia (SETH). Las alternativas a la transfusión se han clasificado en farmacológicas y no farmacológicas, con un total de 4 módulos y 12 tópicos. La disminución de las transfusiones de sangre alogénica y/o el número de pacientes transfundidos fue la principal variable objetivo. El grado de cumplimiento de este objetivo, para cada ATSA, se llevó a cabo siguiendo la metodología Delphi, que clasifica el grado de recomendación desde «A» (apoyado por estudios controlados) hasta «E» (estudios no controlados y opinión de expertos). Los expertos concluyeron que la mayor parte de las indicaciones de las ATSA se sustentan en grados de recomendación medios y bajos, «C», «D» o «E», precisándose nuevos estudios controlados (AU)

The Consensus Document on Alternatives to Allogenic Blood Transfusion (AABT) has been drawn up by a panel of experts from 5 scientific societies. The Spanish Societies of Anesthesiology (SEDAR), Critical Care Medicine and Coronary Units (SEMICYUC), Hematology and Hemotherapy (AEHH), Blood Transfusion (SETS) and Thrombosis and Hemostasis (SETH) have sponsored and participated in this Consensus Document. Alternatives to blood transfusion have been divided into pharmacological and non-pharmacological, with 4 modules and 12 topics. The main objective variable was the reduction of allogenic blood transfusions and/or the number of transfused patients. The extent to which this objective was achieved by each AABT was evaluated using the Delphi method, which classifies the grade of recommendation from A (supported by controlled studies) to E (non-controlled studies and expert opinion). The experts concluded that most of the indications for AABT were based on middle or low grades of recommendation, «C», «D», or «E», thus indicating the need for further controlled studies (AU)