2. Academic Validation
  3. Macrothrombocytopenia and dense granule deficiency associated with FLI1 variants: ultrastructural and pathogenic features

Macrothrombocytopenia and dense granule deficiency associated with FLI1 variants: ultrastructural and pathogenic features

  • Haematologica. 2017 Jun;102(6):1006-1016. doi: 10.3324/haematol.2016.153577.
Paul Saultier 1,  Léa Vidal 2,  Matthias Canault 2,  Denis Bernot 2,  Céline Falaise 3,  Catherine Pouymayou 3,  Jean-Claude Bordet 4,  Noémie Saut 2 3,  Agathe Rostan 2 3,  Véronique Baccini 2 3,  Franck Peiretti 2,  Marie Favier 2,  Pauline Lucca 5 6 7,  Jean-François Deleuze 8,  Robert Olaso 8,  Anne Boland 8,  Pierre Emmanuel Morange 2 3,  Christian Gachet 9 10 11 12,  Fabrice Malergue 13,  Sixtine Fauré 2,  Anita Eckly 9 10 11 12,  David-Alexandre Trégouët 5 6 7,  Marjorie Poggi 2,  Marie-Christine Alessi 2 3
Affiliations

Affiliations

  • 1 Aix Marseille Univ, INSERM, INRA, NORT, Marseille, France paul.saultier@gmail.com.
  • 2 Aix Marseille Univ, INSERM, INRA, NORT, Marseille, France.
  • 3 APHM, CHU Timone, French Reference Center on Inherited Platelet Disorders, Marseille, France.
  • 4 Unité d'Hémostase Biologique, Bron, France.
  • 5 ICAN Institute for Cardiometabolism and Nutrition, Paris, France.
  • 6 Inserm, UMR_S 1166, Team Genomics and Pathophysiology of Cardiovascular Diseases, Paris, France.
  • 7 Sorbonne Universités, Université Pierre et Marie Curie (UPMC Univ Paris 06), UMR_S 1166, France.
  • 8 Centre National de Génotypage, Institut de Génomique, CEA, Evry, France.
  • 9 UMR_S949 INSERM, Strasbourg, France.
  • 10 Etablissement Français du Sang (EFS)-Alsace, Strasbourg, France.
  • 11 Fédération de Médecine Translationnelle de Strasbourg (FMTS), France.
  • 12 Université de Strasbourg, Marseille, France.
  • 13 Beckman Coulter Immunotech, Life Sciences Global Assay and Applications Development, Marseille, France.
PMID: 28255014 DOI: 10.3324/haematol.2016.153577
Abstract

Congenital macrothrombocytopenia is a family of rare diseases, of which a significant fraction remains to be genetically characterized. To analyze cases of unexplained thrombocytopenia, 27 individuals from a patient cohort of the Bleeding and Thrombosis Exploration Center of the University Hospital of Marseille were recruited for a high-throughput gene Sequencing study. This strategy led to the identification of two novel FLI1 variants (c.1010G>A and c.1033A>G) responsible for macrothrombocytopenia. The FLI1 variant carriers' platelets exhibited a defect in aggregation induced by low-dose adenosine diphosphate (ADP), collagen and Thrombin receptor-activating peptide (TRAP), a defect in adenosine triphosphate (ATP) secretion, a reduced mepacrine uptake and release and a reduced CD63 expression upon TRAP stimulation. Precise ultrastructural analysis of platelet content was performed using transmission electron microscopy and focused ion beam scanning electron microscopy. Remarkably, dense granules were nearly absent in the carriers' platelets, presumably due to a biogenesis defect. Additionally, 25-29% of the platelets displayed giant α-granules, while a smaller proportion displayed vacuoles (7-9%) and autophagosome-like structures (0-3%). In vitro study of megakaryocytes derived from circulating CD34+ cells of the carriers revealed a maturation defect and reduced proplatelet formation potential. The study of the FLI1 variants revealed a significant reduction in protein nuclear accumulation and transcriptional activity properties. Intraplatelet flow cytometry efficiently detected the biomarker MYH10 in FLI1 variant carriers. Overall, this study provides new insights into the phenotype, pathophysiology and diagnosis of FLI1 variant-associated thrombocytopenia.

Figures