Crohn’s disease [CD] is an inflammatory bowel disease [IBD] characterized by chronic inflammation of any part of the gastrointestinal tract with a progressive and destructive course; its incidence is increasing worldwide.1,2 Its aetiology remains unclear, with a strong contribution from the distorted microbiota.3–13 The disease is incurable, with a multitude of therapeutic strategies available: in the last decade, tumour necrosis factor alpha blockers [anti-TNF] have been established as easily available and highly effective treatments.14 This evidence concerns the gene TNF and irritable bowel syndrome.