Investigation of responsible genes for early inflammatory bowel disease and inflammatory bowel disease-like colitis in children

Inflammatory bowel disease (IBD) is a chronic inflammatory disease of the gastrointestinal tract. Very early onset IBD and early onset IBD are terms used to describe IBD that first presents before the age of six and before the age of ten, respectively. It is known that genetic predisposition is important especially in very early-onset IBD. Monogenic causes are thought to be more common in the pathogenesis of early onset IBD and IBD-like diseases. The aim of our study is to investigate the responsible genes involved in the pathogenesis of early-onset IBD and IBD-like chronic diarrhea. The study included patients aged 0-18 years who were being followed up in Hacettepe University Pediatric Gastroenterology, Hepatology and Nutrition Unit for early-onset IBD or IBD-like chronic diarrhea. Whole exome sequencing was established for patients who were not diagnosed with monogenic disease with classical Sanger sequencing and next generation sequencing before the study started. The study included 47 patients [14 girls (29.8%), 33 boys (70.2%)]. The median age of onset of symptoms was 36 months (IQR 10-72), and the median age at diagnosis of IBD was 3.7 years (IQR 1.5-7.6). Crohn's disease was present in 25 patients (53.2%), ulcerative colitis in 18 patients (38.3%), and indeterminate colitis in four patients (8.5%). Nine patients were diagnosed with Familial Mediterranean Fever, two with glycogen storage disease type 1b, one with XIAP defect, one with chronic granulomatous disease, one with DOCK8 defect, one with IL10 receptor alpha defect, one with LRBA deficiency and one with NFKB2 deficiency. In our study, seventeen patients (36.2%) were diagnosed with a disease that could cause early-onset IBD. A SLC29A3 gene variant, which has not been previously associated with IBD was detected in 36 patients (76.6%). This variant was thought to be important in patients with IBD. It can be thought that other variants found in the study may predispose to IBD.