This is a prospective, observational research study for patients with IBD under the care of a gastroenterologist provider. The objective of the Corrona Inflammatory Bowel Diseases (IBD) Registry is to create a national cohort of patients with IBD.The diseases under study include Crohn's Disease (CD), Ulcerative Colitis (UC) and Indeterminate Colitis (IC). Data collected will be used to better characterize the natural history of the disease and to extensively evaluate the effectiveness and safety of medications approved for the treatment of IBD .Approximately 10,000 patients and 150 clinical sites in North America will be recruited to participate with no defined upper limit for either target. The Corrona IBD Registry is a long-term observational study; therefore, the duration of the registry has no pre-determined stop date.

The purpose of this study is to see whether oral Ozanimod is safe and effective for treating Crohn's disease. Adult participants (at least 18 years old) with moderately to severely active Crohn's disease may be eligible.

Only participants who complete the induction and/or maintenance study will be eligible to join this open-label study.

All participants in this study receive active study drug. The dose of study drug you will receive will depend on your prior study. There is no chance of placebo in this study.

This study is designed to last up to 234 weeks (4.5 years). Participants are expected to come to MUSC every 8 or 12 weeks for study visits.

The purpose of this study is to see whether Ozanimod is safe and effective for treating Crohn's disease. Adult participants (at least 18 years old) with moderately to severely active Crohn's disease may be eligible.

To do this, a comparison will be made between subjects who receive active drug and subjects who receive placebo (a ‘dummy treatment' that looks like the active drug but contains no active ingredient). The chance of being randomized (like drawing names out of a hat) into ozanimod group and receiving ozanimod is 50%. The chance of being randomized into placebo group and receiving placebo is 50%.

If participants' Crohn's disease condition get worse during the study, they will be invited to participate the open-label study, which has no placebo.

This is a one-year study, and participants are expected to come to MUSC every 8 weeks for study visits.

The purpose of this study is to see whether Ozanimod is safe and effective for treating Crohn's disease. Participants who are aged 18 to 75 years with moderately to severely active Crohn's disease may be eligible.

To do this, a comparison will be made between subjects who receive active drug and subjects who receive placebo (a ‘dummy treatment' that looks like the active drug but contains no active ingredient). The chance of being randomized (like drawing names out of a hat) into ozanimod group and receiving ozanimod is 67%. The chance of being randomized into placebo group and receiving placebo is 33%.

This study is designed to last up to 30 weeks, including 2 screening visits, 4 study visits, and 2 follow-up visits. The study drug may improve participant's Crohn's disease condition, but this cannot be guaranteed.