Genetic analysis of NOD2 in patients with intestinal tuberculosis and Crohn's disease in Korea

Background and aims: Nod2 is an intracellular pathogen sensor found to be associated with susceptibility to Crohn's disease (CD) in Western countries. However, the results from Asian population including Koreans showed discordant findings. Meanwhile, a recent study demonstrated significant associations between NOD2 polymorphisms and tuberculosis (TB). However, in Korea, no studies on NOD2 mutations in TB patients have been conducted as of yet. Methods: We collected the surgically resected intestines confirmed as TB with more than one positivity among TB-polymerase chain reaction, Ziehl-Neelsen stain, and culture for Mycobacterium tuberculosis. CD was confirmed on the basis of usual clinico-pathological criteria with all negativity for aforementioned tests and without other infectious causes. DNA extracted from the formalin-fixed, paraffin-embedded tissues of patients with intestinal TB (14), CD (19), and controls (18) were amplified by PCR using five primers for Ala140Thr, Pro268Ser, Arg702Trp, Arg708His, Ala725Gly, Gly908Arg, and Leu1007fs. DNA sequencing was then performed. Results: Histologically, well-defined granulomas with caseous necrosis were found in all TB but not in any CD. We found no mutations related to CD as well as TB in DNA sequencing. Conclusions: This result reconfirmed that the molecular changes associated with CD in Asian populations might differ from Western populations. Furthermore, the genetic change associated with TB in Korea is still remains to be clarified.