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A gain-of-function variant in DIAPH1 causes dominant macrothrombocytopenia and hearing loss

2016; Elsevier BV; Volume: 127; Issue: 23 Linguagem: Inglês

10.1182/blood-2015-10-675629

1528-0020

Simon Stritt, Paquita Nurden, Ernest Turro, Daniel Greene, Sjoert B.G. Jansen, Sarah K. Westbury, R. Petersen, William J. Astle, Sandrine Marlin, Tadbir K. Bariana, Myrto Kostadima, Claire Lentaigne, Stephanie Maiwald, Sofia Papadia, Anne M. Kelly, Jonathan Stephens, Christopher J. Penkett, Sofie Ashford, Salih Tuna, Steve Austin, Tamam Bakchoul, Peter Collins, Rémi Favier, Michele P. Lambert, Mary Mathias, Carolyn M. Millar, Rutendo Mapeta, David J. Perry, Sol Schulman, Ilenia Simeoni, Chantal Thys, Keith Gomez, Wendy N. Erber, Kathleen Stirrups, Augusto Rendon, John R. Bradley, Chris Van Geet, F. Lucy Raymond, Michael Laffan, Alan T. Nurden, Bernhard Nieswandt, Sylvia Richardson, Kathleen Freson, Willem H. Ouwehand, Andrew Mumford,

Blood disorders and treatments

Macrothrombocytopenia (MTP) is a heterogeneous group of disorders characterized by enlarged and reduced numbers of circulating platelets, sometimes resulting in abnormal bleeding. In most MTP, this phenotype arises because of altered regulation of platelet formation from megakaryocytes (MKs). We report the identification of DIAPH1, which encodes the Rho-effector diaphanous-related formin 1 (DIAPH1), as a candidate gene for MTP using exome sequencing, ontological phenotyping, and similarity regression. We describe 2 unrelated pedigrees with MTP and sensorineural hearing loss that segregate with a DIAPH1 R1213* variant predicting partial truncation of the DIAPH1 diaphanous autoregulatory domain. The R1213* variant was linked to reduced proplatelet formation from cultured MKs, cell clustering, and abnormal cortical filamentous actin. Similarly, in platelets, there was increased filamentous actin and stable microtubules, indicating constitutive activation of DIAPH1. Overexpression of DIAPH1 R1213* in cells reproduced the cytoskeletal alterations found in platelets. Our description of a novel disorder of platelet formation and hearing loss extends the repertoire of DIAPH1-related disease and provides new insight into the autoregulation of DIAPH1 activity.