Crohn's disease is a 55% chance the other will too. The incidence of Crohn's disease is increasing in Europe and in newly industrialised countries. For example, in Brazil, there has been an annual increase of 11% in the incidence of Crohn's disease since 1990. Inflammatory bowel diseases were described by Giovanni Battista Morgagni (1682–1771) and by Scottish physician T. Kennedy Dalziel in 1913. "Ileitis terminalis" was first described by Polish surgeon Antoni Leśniowski in 1904, although it was not conclusively distinguished from intestinal tuberculosis. In Poland, it is still called Leśniowski-Crohn's disease (). Burrill Bernard Crohn, an American gastroenterologist at New York
Chronic granulomatous disease from the name of the disease as children survived into adulthood. Gene therapy is currently being studied as a possible treatment for chronic granulomatous disease. CGD is well-suited for gene therapy since it is caused by a mutation in single gene which only affects one body system (the hematopoietic system). Viruses have been used to deliver a normal gp91 gene to rats with a mutation in this gene, and subsequently the phagocytes in these rats were able to produce oxygen radicals. In 2006, two human patients with X-linked chronic granulomatous disease underwent gene therapy and blood cell precursor stem cell