Factor V Quebec revisited.

Factor V Quebec has been described as a bleeding disorder that exhibits an autosomal dominant inheritance pattern and presents severe bleeding after trauma. Two members of a fourth-generation (IV.13 and IV.15) Canadian family have been studied in detail and are the subject of this report. Their clinical presentations and histories have been described previously (Tracy et al: J Clin Invest 74:1221, 1984). Persistent abnormalities include mild thrombocytopenia and defective platelet factor V. Plasma factor V is present at near normal concentration and is fully functional. Thus, the bleeding diathesis appears to reflect the absence of platelet factor V activity. The recent report (Hayward et al: Blood 84:110a, 1994 [suppl, abstr]) of multimerin deficiency in these individuals led us to reevaluate these patients. Western blot analyses of platelet lysates developed with a variety of monoclonal antibodies show that the alpha-granule proteins, fibrinogen, von Willebrand factor, factor V and osteonectin are decreased in concentration and significantly degraded in the platelets of these patients. Thrombospondin, while not degraded, is substantially decreased. In contrast, platelet factor 4 and beta-thromboglobulin do not appear to be affected. These observations suggest that the alpha-granules are correctly assembled but the contents are subsequently subjected to proteolytic degradation. The results indicate that factor V Quebec disorder is probably associated with a generalized defect that leads to degradation of most proteins of the alpha-granules.
AuthorsC M Janeway, G E Rivard, P B Tracy, K G Mann
JournalBlood (Blood) Vol. 87 Issue 9 Pg. 3571-8 (May 01 1996) ISSN: 0006-4971 [Print] United States
PMID8611679 (Publication Type: Journal Article, Research Support, U.S. Gov't, P.H.S.)
Chemical References
  • Blood Proteins
  • Factor V
  • Blood Proteins (analysis, genetics)
  • Canada
  • Enzyme-Linked Immunosorbent Assay
  • Factor V (analysis, genetics)
  • Factor V Deficiency (blood, genetics)
  • Humans
  • Immunoblotting

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