Early-onset paediatric inflammatory bowel disease.

The incidence of early-onset paediatric inflammatory bowel disease is increasing worldwide. Defined as a diagnosis of Crohn's disease, ulcerative colitis, or inflammatory bowel disease unclassified before the age of 10 years, the disease is complex, multifactorial, and lifelong, and affects nutrition and psychological wellbeing. Over 200 genes have been implicated and a further 52 genes are known to cause monogenic disease, often presenting in infancy. Heritability of early-onset inflammatory bowel disease is hypothesised to be between that of infantile-onset (ie, <6 years old) and adult-onset disease, with genetic cause characterised by a few genes with modest or large effect size. Although early-onset disease is typically more severe than infantile-onset and adult-onset disease, long-term morbidity has not been assessed. Disease management is multifaceted and multidisciplinary, and is focused on the safe induction of remission and prevention of relapse. Although the advent of monoclonal antibody therapy has had a positive effect in the management of inflammatory bowel disease, treatment effects in early-onset inflammatory bowel disease are less certain. Additional challenges include maintenance of growth, navigation of puberty, and transition to adult services for long-term management.