title: Very early-onset inflammatory bowel disease: gaining insight through focused discovery.
abstract: The pathogenesis of pediatric inflammatory bowel disease (IBD) is only partially understood. Strong evidence implicates a strong genetic component including high monozygotic twin concordance and familial disease phenotype concordance rates. Genome-wide association studies have identified associations between >160 genetic loci and the risk for developing IBD. The roles of implicated genes are largely immune-mediated, although other functions include cellular migration, oxidative stress, and carbohydrate metabolism. Additionally, growing literature describes monogenic causes of IBD that frequently present as infantile or very early-onset IBD. The interplay between IBD risk single nucleotide polymorphisms and rare genetic variants has yet to be determined. Studying patients with very early-onset IBD may elicit genetic factors that could be applied to broader populations of IBD. This review describes what is known about the genetic causes of very early-onset IBD and genetic strategies that may unravel more of the genetic causes of IBD.
authors.affiliation: *Division of Pediatric Gastroenterology, Hepatology, and Nutrition, Department of Pediatrics, MassGeneral Hospital for Children, Boston, Massachusetts; †Department of Pediatrics, Harvard Medical School, Boston, Massachusetts; ‡Dr von Hauner Children's Hospital, Ludwig Maximilians University, Munich, Germany; §Division of Gastroenterology, Hepatology, and Nutrition, Department of Paediatrics, University of Toronto, Hospital for Sick Children, Toronto, ON, Canada; ‖SickKids Inflammatory Bowel Disease Center and Cell Biology Program, Research Institute, Hospital for Sick Children, Toronto, ON, Canada; ¶Division of Pediatric Gastroenterology, Hepatology, and Nutrition, Department of Medicine, Children's Hospital Boston, Boston, Massachusetts; **Division of Gastroenterology and Hepatology, Brigham & Women's Hospital, Boston, Massachusetts; and ††Department of Medicine, Harvard Medical School, Boston, Massachusetts.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Moran
authors.forename: Christoph
authors.initials: C
authors.lastname: Klein
authors.forename: Aleixo M
authors.initials: AM
authors.lastname: Muise
authors.forename: Scott B
authors.initials: SB
authors.lastname: Snapper
mesh_terms: D017668:Age of Onset; D056426:Genetic Loci; D020022:Genetic Predisposition to Disease; D055106:Genome-Wide Association Study; D006801:Humans; D015212:Inflammatory Bowel Diseases / Q000235:genetics*; D010641:Phenotype; D011379:Prognosis; D057170:Translational Research, Biomedical