Familial occurrence of inflammatory bowel disease in children

Introduction: Familial occurrence of inflammatory bowel disease (IBD) is one of the most important risk factors for this group of diseases. In the first-degree relatives the risk of IBD increases 10- to 15-fold and among more distant relatives 3-fold. The NOD2/CARD15 gene mutation may lead to the development of IBD. But not all the patients with this mutation developed intestinal inflammation. This can indicate a complex relationship between genes and environment necessary for the development of IBD. Aim of the study: To assess the prevalence of familial IBD in children, their clinical course, and the presence of NOD2/ CARD15 gene mutations in children with familial and sporadic Crohn’s disease (CD). Material and methods: The study comprised 178 children with IBD aged 3-18 years - 80 children with CD and 98 with ulcerative colitis (UC). The analysis included: age at the diagnosis, sex, disease activity (PCDAI, PUCAI). In children with CD, mutations R702W, G908R, L1007fs of the NOD2/CARD15 gene were marked. Familial occurrence is defined as occurrence of at least one patient with IBD among first-, second- and third-degree relatives. Results: Familial IBD occurred in 10.7% of patients - 11.2% in CD, 10.2% in UC. Among the studied children, the familial form of UC occurred in children at the younger age by 2 years. Children with familial CD had twice as likely a severe form (p=0.028), in children with familial UC significantly more common was a moderate form (p=0.0029). Almost all children with familial CD (88.9%) and 35.2% of children with sporadic CD (p=0.001) had at least one mutation of the NOD2/CARD15 gene. Considering the single NOD2/CARD15 gene mutations, in both the family and the sporadic forms the most common was L1007fs mutation. Conclusions: Familial occurrence of inflammatory bowel disease in children was similar to the adult population and their clinical course was much more severe than in patients with the sporadic form. The high frequency of the mutations of the NOD2/CARD15 gene confirms the dominant genetic factor in the pathogenesis of familial CD.