Novel XIAP mutation causing enhanced spontaneous apoptosis and disturbed NOD2 signalling in a patient with atypical adult-onset Crohn's disease

Cell Death Dis. 2020 Jun 8;11(6):430. doi: 10.1038/s41419-020-2652-4.


X-linked inhibitor of apoptosis (XIAP) is the most potent human inhibitor of apoptosis, and is also involved in NOD2-dependent NFκB and MAPK signalling cascade activation. The absence or defective function of XIAP leads to the development of a rare and severe primary immunodeficiency known as X-linked lymphoproliferative syndrome type 2 (XLP-2), which is characterized by a triad of clinical manifestations, including a high incidence of haemophagocytic lymphohistiocytosis (HLH), lymphoproliferation and inflammatory bowel disease (IBD), usually with very early onset. Here, we present a novel XIAP mutation identified in a patient with atypical adult-onset IBD complicated by relapsing HLH, splenomegaly and sarcoid-like disease. The c.266delA mutation in the XIAP gene creates a premature stop codon, and causes a severe reduction in XIAP protein expression. The mutation is also associated with impaired spontaneous and staurosporine- and PMA-induced apoptosis accompanied by significantly increased expression of pro-apoptotic genes. We also confirmed the negative impact of this particular XIAP mutation on NOD2-dependent NFκB and MAPK activation, while NOD2-independent activation was found to be unaffected. Moreover, we assume that the mutation has an impact on the overproduction of IL-12 and IFNγ, the shift towards the Th1 immune response and increased numbers of central memory and effector memory CD4+ and CD8+ T cells. All these changes contribute to immune dysregulation and the clinical manifestation of XLP-2.

Publication types

  • Case Reports
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Apoptosis
  • Crohn Disease / genetics*
  • Crohn Disease / pathology
  • Humans
  • Mutation
  • Nod2 Signaling Adaptor Protein / metabolism*
  • Signal Transduction
  • X-Linked Inhibitor of Apoptosis Protein / metabolism*


  • NOD2 protein, human
  • Nod2 Signaling Adaptor Protein
  • X-Linked Inhibitor of Apoptosis Protein
  • XIAP protein, human