Retrospective Study
Copyright ©The Author(s) 2020. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastrointest Pharmacol Ther. Sep 8, 2020; 11(4): 69-78
Published online Sep 8, 2020. doi: 10.4292/wjgpt.v11.i4.69
Role of telomere shortening in anticipation of inflammatory bowel disease
Brindusa Truta, Elizabeth Wohler, Nara Sobreira, Lisa W. Datta, Steven R. Brant
Brindusa Truta, Lisa W. Datta, Steven R Brant, Division of Gastroenterology & Hepatology, Johns Hopkins University School of Medicine, Baltimore, MD 21210, United States
Elizabeth Wohler, Nara Sobreira, McKusick-Nathan Institute of Genetics, Johns Hopkins School of Medicine, Baltimore, MD 21205, United States
Steven R. Brant, Division of Gastroenterology and Hepatology, Department of Medicine, Rutgers-Robert Wood Johnson Medical School, NJ, 08901, United States
Author contributions: Truta B designed the study, performed analysis and wrote the manuscript; Wohler E performed genetic analysis, interpreted the results, reviewed the manuscript; Sobreira N performed genetic analysis; Datta L contributed to data collection; Brant S contributed to study design, data interpretation and editing the manuscript.
Supported by Atran Foundation, NO. 00313651.
Institutional review board statement: This study was reviewed and approved by the Ethics Committee of the Johns Hopkins School of Medicine.
Informed consent statement: Informed written consent was obtained from the patients.
Conflict-of-interest statement: The authors declare that they have no conflicts of interest.
Data sharing statement: No additional data are available.
Open-Access: This article is an open-access article that was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution NonCommercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Corresponding author: Brindusa Truta, MD, Assistant Professor, Division of Gastroenterology & Hepatology, Johns Hopkins University School of Medicine, 1830 E Monument Street, Room 426, Baltimore, MD 21210, United States. btruta1@jhmi.edu
Received: March 28, 2020
Peer-review started: March 28, 2020
First decision: April 25, 2020
Revised: June 25, 2020
Accepted: August 15, 2020
Article in press: August 15, 2020
Published online: September 8, 2020
Processing time: 156 Days and 14.3 Hours
ARTICLE HIGHLIGHTS
Research background

The existence of genetic anticipation, a phenomenon in which an inherited disorder manifests at a younger age and often more severely in offspring than in the affected parent, has been long disputed in inflammatory bowel disease (IBD). In the absence of the explanatory mechanism, it has been suggested that anticipation may result from observation bias. In monogenetic degenerative neurological disorders the mechanism for genetic anticipation was identified as unstable genomic triple repeats. In polygenic diseases, such as IBD, the complexity of multifactorial inheritance makes the identification of genetic mechanism very challenging. I Most recently, mutations in the telomerase reverse transcriptase, have been shown to lead to progressive telomere shortening, causing earlier onset of disease in successive generations with telemeropahities. Telomere length (TL) has also been found to be associated with severity of inflammation and colon cancer in IBD.

Research motivation

The role of TL in genetic anticipation of patients with IBD has not been studied.

Research objectives

In our study, the primary objective was to evaluate generational changes in TL in parent-child pairs of familial IBD, to determine the role of telomere shortening, and its potential implication as a mechanism of anticipation in familial IBD. The secondary objective focused on investigating potential candidate gene variants for autosomal inheritance in these multi-generation IBD families.

Research methods

We studied three IBD families with multiple affected members in three successive generations. We determined TL in lymphocytes and granulocytes from peripheral blood of the affected members using flow cytometry and fluorescence in-situ hybridization (flow FISH). We also performed whole exome sequencing (WES) in the blood of all available family members and used PhenoDB to identify potential candidate gene variants for recessive or dominant modes of inheritance.

Research results

Out of twenty-four patients of European descent selected to participate in the study, eleven patients, eight parent-child pairs affected by IBD, were included in the genetic anticipation analysis. Median difference in age at diagnosis between two successive generations was 16.5 years, with earlier age at onset in the younger generations. Five patients were affected by ulcerative colitis, four patients by Crohn’s disease and two patients by IBD-Unclassified. In most of the affected members, the disease harbored similar gastrointestinal and extraintestinal involvement but was more aggressive among the younger generations. TL was not associated with earlier age at onset or with more severe disease in members of successive generations affected by IBD. NOD2 gene mutations were present in the Crohn’s affected patients of one family. However, no gene variants were identified as potential candidates for Mendelian inheritance.

Research conclusions

The study represents the first evaluation of TL defects in genetic anticipation of IBD. Even though no association was found between TL and age at disease onset among members of successive generations, this pilot study is very valuable as an attempt to find the molecular mechanism of genetic anticipation in IBD.

Research perspectives

While we have shown that genetic anticipation is unlikely to be the result of telomere shortening, our results do point the way to exploration of other mechanisms. Further studies to confirm our findings should address a larger population of familial IBD that likewise have strong evidence for anticipation among successive generations.