title: Thrombocytopenia with absent radii syndrome: studies on serum thrombopoietin levels and megakaryopoiesis in vitro.
abstract: OBJECTIVE
  The pathogenesis of thrombocytopenia in patients with thrombocytopenia with absent radii (TAR) syndrome has not been clarified yet.
  
  
  METHODS
  This is the first report of a Japanese patient with TAR syndrome. We studied his megakaryopoiesis in vitro and serum levels of thrombopoietin (TPO).
  
  
  RESULTS
  Serum levels of TPO in the patient with TAR syndrome were comparable with those of an age-matched control. The bone marrow cells from the patient with TAR syndrome actually generated megakaryocyte colonies in the presence of TPO and the numbers were significantly greater than those from the age-matched control marrow. However, megakaryocyte colonies from the marrow cells with TAR syndrome contained a much lower number of cells per colony and the size of the individual megakaryocytes appeared to be smaller.
  
  
  CONCLUSIONS
  These data suggest that megakaryocyte progenitors from patients with TAR syndrome may have decreased proliferative and differentiative capacity to respond to TPO, leading to thrombocytopenia.
authors.affiliation: Department of Pediatrics, National Defense Medical College, Tokorozawa, Saitama, Japan.
authors.forename: I
authors.initials: I
authors.lastname: Sekine
authors.forename: T
authors.initials: T
authors.lastname: Hagiwara
authors.forename: H
authors.initials: H
authors.lastname: Miyazaki
authors.forename: K
authors.initials: K
authors.lastname: Hirayama
authors.forename: H
authors.initials: H
authors.lastname: Dobashi
authors.forename: K
authors.initials: K
authors.lastname: Kogawa
authors.forename: S
authors.initials: S
authors.lastname: Yoshioka
mesh_terms: D006410:Hematopoiesis; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D008533:Megakaryocytes / Q000502:physiology*; D013577:Syndrome; D013921:Thrombocytopenia / Q000097:blood*; D013926:Thrombopoietin / Q000097:blood*
chemical_list: D013926:Thrombopoietin