IBD Biomarker Discovery and Validation Platform

Eligibility Criteria:

Inclusion Criteria:

1. General inclusion criteria for all participants:

   * Age 14 years or older.
   * Able to provide written informed consent; for minors, consent from a legal guardian and assent from the participant will be obtained according to local ethics requirements.
   * Willing to provide clinical information and/or biospecimens, which may include blood, stool, intestinal tissue, or other available biological samples.
   * Able to participate in study-related data and sample collection according to the study protocol.
2. Participants with inflammatory bowel disease:

   * Diagnosed with inflammatory bowel disease, including Crohn's disease, ulcerative colitis, or IBD-unclassified when applicable, according to accepted national or international diagnostic criteria.
   * May be newly diagnosed, previously diagnosed, under routine follow-up, or receiving routine clinical treatment.
   * Clinical data, treatment exposure information, laboratory results, endoscopic findings, histologic findings, imaging findings, biospecimens, and follow-up outcomes may be available or collected.
3. Unaffected first-degree relatives of participants with inflammatory bowel disease:

   * Biological first-degree relatives of participants with inflammatory bowel disease, including parents, siblings, or offspring.
   * No prior diagnosis of inflammatory bowel disease at enrollment.
   * Willing to provide clinical information and/or biospecimens for family-based genetic, environmental, immune, microbiome, and multi-omics analyses.
4. Unrelated healthy controls:

   * Individuals without a diagnosis of inflammatory bowel disease.
   * No first-degree biological relationship to enrolled participants with inflammatory bowel disease.
   * No known active gastrointestinal inflammatory disease at enrollment.
5. Non-IBD disease controls:

   * Individuals with gastrointestinal symptoms or other non-IBD conditions who undergo clinical evaluation but are not diagnosed with inflammatory bowel disease.
   * Clinical information and/or biospecimens may be collected as disease controls when appropriate.

Exclusion Criteria:

* Refusal or inability to provide informed consent or required assent when applicable.
* Active severe infection or chronic infectious disease that may substantially affect biomarker interpretation, including active tuberculosis, active hepatitis B or C, HIV infection, or other clinically significant active infection.
* Pregnancy or lactation at the time of enrollment.
* Severe mental illness, cognitive impairment, or other condition that prevents cooperation with study procedures.
* Known primary extraintestinal autoimmune disease or systemic inflammatory disease that is considered the main disease and may substantially confound biomarker interpretation.
* Current or recent participation in another interventional clinical trial that may substantially affect the study biomarkers or outcome assessments, as judged by the investigator.
* History of malignant tumor or other severe comorbidity that may substantially affect study participation or biomarker interpretation, as judged by the investigator.
* Inadequate biospecimen quality, missing key clinical information, or inability to complete essential study assessments for the relevant analysis.