XIAP deficiency is a mendelian cause of late-onset IBD

Sir, We read with interest the review by Holm Uhlig on monogenic diseases associated with intestinal inflammation.1 XIAP deficiency, caused by X-linked inherited mutations in BIRC4 , is highlighted as a mendelian cause of very early onset IBD. Consistently with the observation of Crohn's disease (CD) in XIAP deficiency, the RING activity of XIAP was recently shown to be required for NOD2-dependent immune responses.2 In his review Dr Uhlig suggests to consider monogenetic diseases as causes for IBD particularly in patients younger than 6 years of age. In addition to the reviewed literature, our group has recently reported …