High prevalence of infectious events in thrombotic thrombocytopenic purpura and genetic relationship with toll-like receptor 9 polymorphisms: experience of the French Thrombotic Microangiopathies Reference Center

Transfusion. 2014 Feb;54(2):389-97. doi: 10.1111/trf.12263. Epub 2013 May 27.

Abstract

Background: Infectious events have been reported as major environmental triggers of thrombotic thrombocytopenic purpura (TTP). We detail here the potential association between infections and TTP.

Study design and methods: We recruited randomly and prospectively a cohort of 280 consecutive TTP patients during a 9-year period. Features of infection were systematically recorded.

Results: Features consistent with an infectious event were observed in 114 patients (41%) at time of TTP diagnosis. Infectious agents were documented in 34 cases and were mainly Gram-negative bacilli. At time of diagnosis infected patients more frequently had fever (p < 0.001). Infections at diagnosis did not impact prognosis and outcome. Thirty-six percent of patients experienced an infectious event during hospitalization, which resulted in more exacerbation of TTP (p = 0.02). Infections were not overrepresented during treatment in patients who received steroids and/or rituximab. Further genetic analysis of toll-like receptor (TLR)-9 functionally relevant polymorphisms revealed that TLR-9 +2848 G and TLR-9 +1174 A genotypes were more frequent in TTP patients than in controls (p = 0.04 and p = 0.026, respectively) and more particularly in patients negative for the Class II human leukocyte antigen system susceptibility allele DRB1*11 (p = 0.001 and p = 0.002, respectively). Haplotypes estimation showed that 1174A-2848G haplotype was significantly more frequent in TTP (p = 0.004), suggesting a primary role for this haplotype variation in conferring a predisposition for acquired TTP.

Conclusion: Infections should be considered as an aggravating factor during the course of TTP. Particular polymorphisms in TLR-9 gene may represent risk factors for TTP.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Female
  • France / epidemiology
  • Genetic Predisposition to Disease
  • Haplotypes
  • Humans
  • Infections / complications*
  • Male
  • Middle Aged
  • Polymorphism, Genetic
  • Prevalence
  • Prospective Studies
  • Purpura, Thrombotic Thrombocytopenic / etiology
  • Purpura, Thrombotic Thrombocytopenic / genetics*
  • Registries
  • Risk Factors
  • Thrombotic Microangiopathies / epidemiology
  • Thrombotic Microangiopathies / genetics
  • Toll-Like Receptor 9 / genetics*

Substances

  • TLR9 protein, human
  • Toll-Like Receptor 9