Germline variants in ETV6 underlie reduced platelet formation, platelet dysfunction and increased levels of circulating CD34+ progenitors.
Variants in ETV6, which encodes a transcription repressor of the E26 transformation-specific family, have recently been reported to be responsible for inherited thrombocytopenia and hematologic malignancy. We sequenced the DNA from cases with unexplained dominant thrombocytopenia and identified six likely pathogenic variants in ETV6, of which five are novel. We observed low repressive activity of all tested ETV6 variants, and variants located in the E26 transformation-specific binding domain (encoding p.A377T, p.Y401N) led to reduced binding to corepressors. We also observed a large expansion of megakaryocyte colony-forming units derived from variant carriers and reduced proplatelet formation with abnormal cytoskeletal organization. The defect in proplatelet formation was also observed in control CD34+cell-derived megakaryocytes transduced with lentiviral particles encoding mutant ETV6. Reduced expression levels of key regulators of the actin cytoskeleton CDC42 and RHOA were measured. Moreover, changes in the actin structures are typically accompanied by a rounder platelet shape with a highly heterogeneous size, decreased platelet arachidonic response, and spreading and retarded clot retraction in ETV6 deficient platelets. Elevated numbers of circulating CD34+cells were found in p.P214L and p.Y401N carriers, and two patients from different families suffered from refractory anemia with excess blasts, while one patient from a third family was successfully treated for acute myeloid leukemia. Overall, our study provides novel insights into the role of ETV6 as a driver of cytoskeletal regulatory gene expression during platelet production, and the impact of variants resulting in platelets with altered size, shape and function and potentially also in changes in circulating progenitor levels.
Aix Marseille Univ, INSERM, INRA, NORT, Marseille, France.
Marjorie
M
Poggi
Aix Marseille Univ, INSERM, INRA, NORT, Marseille, France.
Matthias
M
Canault
Aix Marseille Univ, INSERM, INRA, NORT, Marseille, France.|Inserm U1170, Gustave Roussy, University Paris Sud, Equipe labellisée Ligue contre le Cancer 94805 Villejuif, France.
Marie
M
Favier
Department of Haematology and National Health Service Blood & Transplant, Cambridge University, UK.|MRC Biostatistics Unit, Cambridge, UK.
Ernest
E
Turro
Aix Marseille Univ, INSERM, INRA, NORT, Marseille, France.
Paul
P
Saultier
Aix Marseille Univ, INSERM, INRA, NORT, Marseille, France.
Dorsaf
D
Ghalloussi
Aix Marseille Univ, INSERM, INRA, NORT, Marseille, France.
Veronique
V
Baccini
Aix Marseille Univ, INSERM, INRA, NORT, Marseille, France.
Lea
L
Vidal
Aix Marseille Univ, INSERM, INRA, NORT, Marseille, France.
Anna
A
Mezzapesa
Post-Genomic Platform of Pitié-Salpêtrière (P3S), Pierre and Marie Curie University, F-75013 Paris, France.
Nadjim
N
Chelghoum
Post-Genomic Platform of Pitié-Salpêtrière (P3S), Pierre and Marie Curie University, F-75013 Paris, France.
Badreddine
B
Mohand-Oumoussa
French Reference-Center on Inherited Platelet Disorders, Marseille, France.
Céline
C
Falaise
Assistance Publique-Hôpitaux de Paris, Hôpital Armand Trousseau, Paris, France.
Rémi
R
Favier
Department of Haematology and National Health Service Blood & Transplant, Cambridge University, UK.|Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, UK.
Willem H
WH
Ouwehand
French Reference-Center on Inherited Platelet Disorders, Marseille, France.|Laboratoire d'hématologie, CHU de Bordeaux, Pessac, France.
Mathieu
M
Fiore
Aix Marseille Univ, INSERM, INRA, NORT, Marseille, France.
Franck
F
Peiretti
Aix Marseille Univ, INSERM, INRA, NORT, Marseille, France.|French Reference-Center on Inherited Platelet Disorders, Marseille, France.
Pierre Emmanuel
PE
Morange
Aix Marseille Univ, INSERM, INRA, NORT, Marseille, France.|French Reference-Center on Inherited Platelet Disorders, Marseille, France.
Noémie
N
Saut
Aix Marseille Univ, INSERM, INRA, NORT, Marseille, France.
Denis
D
Bernot
Institute for Immunology and Transfusion Medicine, University Medicine Greifswald, Germany.
Andreas
A
Greinacher
NIHR BioResource - Rare Diseases, Cambridge University Hospitals, Cambridge Biomedical Campus, UK.
Nihr
N
BioResource
LIRYC, Plateforme Technologique et d'Innovation Biomédicale, Hôpital Xavier Arnozan, Pessac, France.
Alan T
AT
Nurden
French Reference-Center on Inherited Platelet Disorders, Marseille, France.|LIRYC, Plateforme Technologique et d'Innovation Biomédicale, Hôpital Xavier Arnozan, Pessac, France.
Paquita
P
Nurden
Department of Cardiovascular Sciences, Center for Molecular and Vascular Biology, KU Leuven, Belgium.
Kathleen
K
Freson
ICAN Institute of Cardiometabolism and Nutrition, F-75013 Paris, France.|Inserm, UMR_S 1166, Team Genomics and Pathophysiology of Cardiovascular Diseases, F-75013 Paris, France.|Sorbonne Universités, Université Pierre et Marie Curie (UPMC Univ Paris 06), UMR_S 1166, F-75013 Paris, France.
David-Alexandre
DA
Trégouët
Inserm U1170, Gustave Roussy, University Paris Sud, Equipe labellisée Ligue contre le Cancer 94805 Villejuif, France.
Hana
H
Raslova
Aix Marseille Univ, INSERM, INRA, NORT, Marseille, France marie-christine.alessi@univ-amu.fr.|French Reference-Center on Inherited Platelet Disorders, Marseille, France.
Marie-Christine
MC
Alessi
D018952:Antigens, CD34 / Q000378:metabolism; D001772:Blood Cell Count; D001792:Blood Platelets / Q000378:metabolism*; D002454:Cell Differentiation; D005190:Family; D005260:Female; D005786:Gene Expression Regulation; D005838:Genotype; D018095:Germ-Line Mutation; D006412:Hematopoietic Stem Cells / Q000166:cytology* / Q000378:metabolism*; D006801:Humans; D006965:Hyperplasia; D008297:Male; D008533:Megakaryocytes / Q000166:cytology / Q000378:metabolism / Q000473:pathology; D010375:Pedigree; D010641:Phenotype; D010976:Platelet Count; D050783:Proto-Oncogene Proteins c-ets / Q000235:genetics* / Q000378:metabolism; D012097:Repressor Proteins / Q000235:genetics* / Q000378:metabolism; D034061:Thrombopoiesis / Q000235:genetics*; D014158:Transcription, Genetic; D000097764:ETS Translocation Variant 6 Protein
D018952:Antigens, CD34; D050783:Proto-Oncogene Proteins c-ets; D012097:Repressor Proteins; D000097764:ETS Translocation Variant 6 Protein
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