The study will include participants who were diagnosed with inflammatory disease and followed up at National Taiwan University Children's Hospital. The investigators will check the NUDT15 gene test, if the participant agrees to do an additional blood test. The result of the gene test will be analyzed and compared with other clinical data.

In inflammatory bowel disease (IBD), thiopurines play an important role in maintenance of steroid-free remission but possess risk of life-threatening neutropenia, which is associated with gene variants of NUDT15 in Asians. In order to better incorporate thiopurines in clinical practice, the investigators aim to summarize the prevalence and impacts of NUDT15 variation in IBD in Taiwan. The study will include participants who were diagnosed with inflammatory disease and followed up at National Taiwan University Children's Hospital. The investigators will check the NUDT15 gene test, if the participant agrees to do an additional blood test. The result of the gene test will be analyzed and compared with other clinical data.

Inclusion Criteria:

• Participants who are diagnosed with inflammatory bowel disease.

Exclusion Criteria:

• Participants who refused to have blood test for NUDT15 gene evaluation.

The study included participants who are diagnosed with inflammatory bowel disease at National Taiwan University Children's Hospital and agree to have blood test for NUDT15 gene evaluation.