Dataset Information

Expanded repertoire of RASGRP2 variants responsible for platelet dysfunction and severe bleeding.

ABSTRACT: Heritable platelet function disorders (PFDs) are genetically heterogeneous and poorly characterized. Pathogenic variants in RASGRP2, which encodes calcium and diacylglycerol-regulated guanine exchange factor I (CalDAG-GEFI), have been reported previously in 3 pedigrees with bleeding and reduced platelet aggregation responses. To better define the phenotype associated with pathogenic RASGRP2 variants, we compared high-throughput sequencing and phenotype data from 2042 cases in pedigrees with unexplained bleeding or platelet disorders to data from 5422 controls. Eleven cases harbored 11 different, previously unreported RASGRP2 variants that were biallelic and likely pathogenic. The variants included 5 high-impact variants predicted to prevent CalDAG-GEFI expression and 6 missense variants affecting the CalDAG-GEFI CDC25 domain, which mediates Rap1 activation during platelet inside-out ?IIb?3 signaling. Cases with biallelic RASGRP2 variants had abnormal mucocutaneous, surgical, and dental bleeding from childhood, requiring ?1 blood or platelet transfusion in 78% of cases. Platelets displayed reduced aggregation in response to adenosine 5'-diphosphate and epinephrine, but variable aggregation defects with other agonists. There were no other consistent clinical or laboratory features. These data enable definition of human CalDAG-GEFI deficiency as a nonsyndromic, recessive PFD associated with a moderate or severe bleeding phenotype and complex defects in platelet aggregation.

SUBMITTER: Westbury SK

PROVIDER: S-EPMC5785798 | biostudies-literature | 2017 Aug

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Expanded repertoire of RASGRP2 variants responsible for platelet dysfunction and severe bleeding.

Westbury Sarah K SK Canault Matthias M Greene Daniel D Bermejo Emilse E Hanlon Katharine K Lambert Michele P MP Millar Carolyn M CM Nurden Paquita P Obaji Samya G SG Revel-Vilk Shoshana S Van Geet Chris C Downes Kate K Papadia Sofia S Tuna Salih S Watt Christopher C Freson Kathleen K Laffan Michael A MA Ouwehand Willem H WH Alessi Marie-Christine MC Turro Ernest E Mumford Andrew D AD

Blood 20170621 8

Heritable platelet function disorders (PFDs) are genetically heterogeneous and poorly characterized. Pathogenic variants in RASGRP2, which encodes calcium and diacylglycerol-regulated guanine exchange factor I (CalDAG-GEFI), have been reported previously in 3 pedigrees with bleeding and reduced platelet aggregation responses. To better define the phenotype associated with pathogenic RASGRP2 variants, we compared high-throughput sequencing and phenotype data from 2042 cases in pedig ...[more]

PMID: 28637664

Similar Datasets

Project description:BackgroundSevere leptospirosis is frequently complicated by a hemorrhagic diathesis, of which the pathogenesis is still largely unknown. Thrombocytopenia is common, but often not to the degree that spontaneous bleeding is expected. We hypothesized that the hemorrhagic complications are not only related to thrombocytopenia, but also to platelet dysfunction, and that increased binding of von Willebrand factor (VWF) to platelets is involved in both platelet dysfunction and increased platelet clearance.Methodology/principal findingsA prospective study was carried out in Semarang, Indonesia, enrolling 33 hospitalized patients with probable leptospirosis, of whom 15 developed clinical bleeding, and 25 healthy controls. Platelet activation and reactivity were determined using flow cytometry by measuring the expression of P-selectin and activation of the αIIbβ3 integrin by the binding of fibrinogen in unstimulated samples and after ex vivo stimulation by the platelet agonists adenosine-diphosphate (ADP) and thrombin-receptor activating peptide (TRAP). Platelet-VWF binding, before and after VWF stimulation by ristocetin, as well as plasma levels of VWF, active VWF, the VWF-inactivating enzyme ADAMTS13, thrombin-antithrombin complexes (TAT) and P-selectin were also measured. Bleeding complications were graded using the WHO bleeding scale. Our study revealed that platelet activation, with a secondary platelet dysfunction, is a feature of patients with probable leptospirosis, especially in those with bleeding manifestations. There was a significant inverse correlation of bleeding score with TRAP-stimulated P-selectin and platelet-fibrinogen binding (R = -0.72, P = 0.003 and R = -0.66, P = 0.01, respectively) but not with platelet count. Patients with bleeding also had a significantly higher platelet-VWF binding. Platelet counts were inversely correlated with platelet-VWF binding (R = -0.74; P = 0.0009. There were no correlations between platelet-VWF binding and the degree of platelet dysfunction, suggesting that increased platelet-VWF binding does not directly interfere with the platelet αIIbβ3 signaling pathway in patients with probable leptospirosis.Conclusion/significancePlatelet dysfunction is common in probable leptospirosis patients with manifest bleeding. Increased VWF-platelet binding may contribute to the activation and clearance of platelets.

Dataset Information

Expanded repertoire of RASGRP2 variants responsible for platelet dysfunction and severe bleeding.

Publications

Expanded repertoire of <i>RASGRP2</i> variants responsible for platelet dysfunction and severe bleeding.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets