eLife (Mar 2018)

IRF4 haploinsufficiency in a family with Whipple’s disease

  • Antoine Guérin,
  • Gaspard Kerner,
  • Nico Marr,
  • Janet G Markle,
  • Florence Fenollar,
  • Natalie Wong,
  • Sabri Boughorbel,
  • Danielle T Avery,
  • Cindy S Ma,
  • Salim Bougarn,
  • Matthieu Bouaziz,
  • Vivien Béziat,
  • Erika Della Mina,
  • Carmen Oleaga-Quintas,
  • Tomi Lazarov,
  • Lisa Worley,
  • Tina Nguyen,
  • Etienne Patin,
  • Caroline Deswarte,
  • Rubén Martinez-Barricarte,
  • Soraya Boucherit,
  • Xavier Ayral,
  • Sophie Edouard,
  • Stéphanie Boisson-Dupuis,
  • Vimel Rattina,
  • Benedetta Bigio,
  • Guillaume Vogt,
  • Frédéric Geissmann,
  • Lluis Quintana-Murci,
  • Damien Chaussabel,
  • Stuart G Tangye,
  • Didier Raoult,
  • Laurent Abel,
  • Jacinta Bustamante,
  • Jean-Laurent Casanova

DOI
https://doi.org/10.7554/eLife.32340
Journal volume & issue
Vol. 7

Abstract

Read online

Most humans are exposed to Tropheryma whipplei (Tw). Whipple’s disease (WD) strikes only a small minority of individuals infected with Tw (<0.01%), whereas asymptomatic chronic carriage is more common (<25%). We studied a multiplex kindred, containing four WD patients and five healthy Tw chronic carriers. We hypothesized that WD displays autosomal dominant (AD) inheritance, with age-dependent incomplete penetrance. We identified a single very rare non-synonymous mutation in the four patients: the private R98W variant of IRF4, a transcription factor involved in immunity. The five Tw carriers were younger, and also heterozygous for R98W. We found that R98W was loss-of-function, modified the transcriptome of heterozygous leukocytes following Tw stimulation, and was not dominant-negative. We also found that only six of the other 153 known non-synonymous IRF4 variants were loss-of-function. Finally, we found that IRF4 had evolved under purifying selection. AD IRF4 deficiency can underlie WD by haploinsufficiency, with age-dependent incomplete penetrance.

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