Role of telomere shortening in anticipation of inflammatory bowel disease.

Background: The existence of genetic anticipation has been long disputed in inflammatory bowel disease (IBD) in the absence of the explanatory mechanism.

Aim: To determine whether it was predictive of genetic anticipation, we evaluated telomere length in IBD. We hypothesized that multiplex IBD families exhibit a genetic defect impacting telomere maintenance mechanisms.

Methods: We studied three IBD families with multiple affected members in three successive generations. We determined telomere length (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 in the blood of all available family members and used PhenoDB to identify potential candidate gene variants with recessive or dominant modes of inheritance.

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. 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 more severe disease in members of successive generations affected by IBD. NOD2 gene mutations were present in the Crohn's disease patients of one family. However, no gene variants were identified as potential candidates for inheritance.

Conclusion: Telomere shortening appears unlikely to be involved in mechanisms of possible genetic anticipation in IBD. Further studies using a larger sample size are required to confirm or refute our findings.