Jacobs Journal of Internal Medicine

The Genetics of Inflammatory Bowel Disease

*Lijiang Ma
Department Of Pediatrics And Medicine, Columbia University, New York, United States

*Corresponding Author:
Lijiang Ma
Department Of Pediatrics And Medicine, Columbia University, New York, United States
Email:lm2689@columbia.edu

Published on: 2015-07-13

Abstract

Inflammatory bowel disease (IBD) is considered as genetic disease due to observation of familial clustering of cases, genetic anticipation between generations and phenotypic concordance of some clinical features within families. Current knowledge of genes/loci associated IBD was largely developed by genome wide association studies which is common disease-common variant analysis strategy. With heterogeneity character and disease incidence of 4.75/100,000/year for Crohn’s disease and 2.06/100,000/year for ulcerative colitis in pediatric population, targeted resequencing and whole exome sequencing for the identification of rare pathogenic variants in known or novel genes are becoming more applicable for IBD genetic studies. According to chromosomal locus of genetic susceptibility, IBD was classified into 28 subtypes. According to functions and pathogenesis, genes involved in IBD can be classified into three groups including inflammation, immune regulation, and cellular adhesion/epithelial barrier integration. Genes regulate cell cycle, dysplasia or adhesion may be associated with cancer development in patients with long-standing IBD. Identification of casual genes/variants will be significant for diagnosis, treatment, prevention, cancer surveillance and improved health care for IBD patients.

Keywords

Inflammatory bowel disease; Crohn’s disease; Ulcerative colitis; Genetics

Introduction

Inflammatory bowel disease (IBD) is a group of disorders that can be classified as Crohn’s disease (CD) and ulcerative colitis (UC). It is thought that the disease results from deregulation of homeostasis of gastrointestinal tract which is caused by inappropriate immune response to intestinal microbes. Although CD and UC have different pathophysiological entities, their clinical presentations (such as abdominal pain, nausea, vomiting, diarrhea and constipation) are similar and non-specific. Diagnosis can be made by symptoms, laboratory tests, radiology, endoscopic examination and pathological findings. Differential diagnosis includes infectious colitis, acute self-limited colitis, diverticulitis, pseudomembranous colitis, irritable bowel syndrome, celiac disease, medication, allergy and cancer. Despite of advance in technology, an accurate diagnosis cannot be achieved in 10% of IBD patients. Affected individuals with colonic disease that cannot be specified are classified as indeterminate colitis. In pediatric series, the prevalence of indeterminate colitis ranges from 5-30%, suggesting variation in classification criteria and uncertainty in diagnosis [1,2].