Attempts to comprehensively understand the epidemiologic, clinical, and genetic characteristics of Korean CD patients started in 2008. Won Ho Kim at Yonsei University, President of the Korean Association for the Study of Intestinal Diseases (KASID) at that time, obtained a national grant, the "Research Network for Crohn's Disease." The four major aims of the study were as follows: (1) understand the epidemiologic and clinical characteristics by establishing a registered database of CD patients; (2) establish a genetic research management system and a genetic biobank by obtaining blood specimens and clinical data from CD patients; (3) establish a network of doctors specialized in CD treatment and patients with CD as a private non-profit organization; and (4) develop specific Korean diagnostic and therapeutic guidelines for CD. During the study period, clinical data from nearly 2,000 blood specimens (both genomic DNA and sera) of 1,316 Korean CD patients were collected and stored at the Korean Green Cross Corporation. Active translational research by basic and clinical researchers is now underway using these samples.^8,9 In addition, this study team established a nationwide doctor-patient network by hosting educational workshops for patients and symposiums for clinicians via the regional society meetings every year (Seoul, Gyunggi, Daegu, and Daejeon). These provided disease information, life style education, counseling, and various programs for patients and their families, including one ensuring patients' rights. This study team also established and published the Korean diagnostic and therapeutic guidelines for CD with the help of the IBD Study Group of KASID^10,11 that published the diagnostic guidelines for intestinal tuberculosis, a disease often misdiagnosed as CD, in the same year.¹² Through an e-mail survey, the IBD Study Group of KASID monitored the effectiveness of the diagnostic guidelines in clinical practice, investigated clinician satisfaction with the guidelines, and collected feedback on ways to improve the guidelines.¹³ At that time, the chair of IBD study group was Professor Joo Sung Kim at Seoul National University.

After the nationally funded Research Network for Crohn's Disease study ended, a better-designed cohort study involving prospective collection of clinical data was planned. The Korea Eisai Company sponsored a two-year educational grant for this CD cohort study. This study followed the Research Network for Crohn's Disease study and was named Establishment of Crohn's disease in Korea and characterization of clinical features with long-term follow-up, and was conducted from January 2012 to December 2013. This study team was led by Dong Soo Han, a Professor at the Hanyang University and the current vice president of KASID. Retrospective clinical data (for patients enrolled before 2009) and prospective clinical data (for patients enrolled during and after 2009) were collected in this study. The prospective patients were enrolled using a novel web-based eCRF system (www.cdcohort.org). Data for 1,388 retrospective patients and 890 prospective patients were collected and analyzed. A study coordinator monitored submission and quality of eCRF data. Blood specimens were collected from 635 of the prospective patients and stored in a deep freezer at -80℃. During this study, the IBD study group chair was Professor Young Ho Kim at the Sungkyunkwan University, who organized the clinical and translational studies that utilized these data. This study was registered at www.clinicaltrials.gov. The first results using the prospective data were presented during the 2014 regular meeting of the European Crohn's and Colitis Organization in Copenhagen, Denmark. The most important and innovative outcomes from this study were the establishment of a novel eCRF system to collect well-recorded, high-quality prospective data and the development of the associated data input protocol (the latter of which was led by Professor Byong Duk Ye).

In 2012, the Cardiovascular and Rare Disease Section, Korea Centers for Disease Control and Prevention (www.cdc.go.kr) solicited grant applications for a 6-month demonstration project aimed at establishing a CD network (to run from August 2012 to December 2012). The KASID obtained this grant, and in 2012, for a 3-year national grant from the Korea Centers for Disease Control and Prevention. The new study funded by these grants was named Establishment and Management of Crohn's Disease Research Network. The principal aim of this study was to broaden the pool of study subjects by recruiting additional investigators throughout Korea. Consequently, 28 institutions were recruited to participate in this study. Currently, Professor Joo Sung Kim at the Seoul National University is in charge of the study. The current chair of the IBD study group is Professor Kang Moon Lee at the Catholic University, and he is currently supervising the investigators and study projects working with the collected data.

Recently, the latter two studies discussed above were integrated into a single study referred to as the Crohn's Disease Clinical Network and Cohort (CONNECT) study (Fig. 1). A total of 34 institutions are now participating in this study, and 1,900 blood specimens have been collected. Four abstracts were presented at the regular KASID meeting in April 2014. From the CONNECT study, investigators anticipate that the typical clinical characteristics and genetic causes of CD in Korean patients will be elucidated. Additional diagnosis and treatment guidelines and therapeutic agents for Korean CD patients will be developed based on these data. Additionally, we anticipate that after analysis, the collected data will be presented at international symposiums and the papers published. By following up with the registered patients, long-term clinical characteristics and accuracy of initial diagnosis can also be investigated. Long-term follow-up results from the CONNECT study should help clinicians and researchers more accurately define CD prognosis in Korea, provide specific health care planning and education, and identify causative factors for CD in Korea, where the incidence of CD is rapidly increasing.