Pharmacogenetic biomarkers of response in Crohn's disease.

Crohn's disease (CD) is a chronic condition, which affects the immune system. It can also affect any part of the digestive tract and be associated with external manifestations. The causes of the disease remain unknown, although it seems to be the result of a combination of factors, such as genetic predisposition, environment, lifestyle and the composition of the microbiota, among others. The treatment protocol begins with a change in eating and smoking habits, and is continued with different lines of treatment, including corticosteroids, immunomodulators and biologic therapy (infliximab and adalimumab), which have shown differences in response among patients, especially with biologic treatment. Several studies have considered the possibility that these differences in response are caused by the genetic variability of patients. Many genes have been investigated as potential predictors of response to biological drugs, such as ADAM17, ATG16L1, EMSY, CASP9, CCNY, CNTN5, FASLG, FCGR, NOD2, PTGER4, IL13, IL1B, IL27, IL11, IL17F, TNF and TNFR genes. In this review, we will gather the information on influence of gene polymorphisms investigated to date on response to biological drugs in CD patients.