Pediatric inflammatory bowel disease: specificity of very early onset.

INTRODUCTION: The incidence of inflammatory bowel disease (IBD) has increased over the last 50 years. It is now recognized that several genetic defects can express an IBD-like phenotype at very early onset (<6 years).

AREAS COVERED: The aim of this review was to update knowledge concerning the specificity of IBD at onset <6 years, which can include conventional/standard IBD as well as monogenic IBD-like diseases. Expert commentary: We found that females are less prone than males to develop monogenic disorders, which have X-linked heritability in several cases. Furthermore, the Crohn's Diseases (CD) subtype seems to be suggestive of monogenic disorders while Unclassified IBD (IBDU) subtype is predominantly found in conventional/standard IBD at onset <6 years. Isolated colonic location is prevalent in both the subsets of IBD at onset <6 years if compared to IBD at later onset. Monogenic disorders require more aggressive medical and surgical treatments and can be complicated by the occurrence of lymphomas.