The affected child in the current study was selected from > 300 children with Crohn disease onset younger than age 12 years. Crohn disease was defined using standard clinical, radiographic, endoscopic, and histological criteria described in the NIDDK IBD Genetics Consortium Phenotyping Form and Manual.

The source of controls are DNA samples selected from ~1000 samples that we collected from healthy adults. At enrollment, we screened these individuals for a personal or family history of 15 autoimmune conditions, and a personal or family history of diarrhea and/or unexplained rectal bleeding and excluded them if they had any of these present.