Genetic Testing of Suspected Intestinal Behçet’s Disease to Identify Monogenic Mimics

Background: Intestinal Behçet’s disease is difficult to distinguish from other immune-mediated inflammatory diseases of the gastrointestinal tract such as Crohn’s disease. In recent studies, researchers have reported that multiple monogenic autoinflammatory diseases can mimic Behçet’s disease, making differential diagnosis more challenging. We aim to retrospectively describe the clinical and laboratory features of six pediatric cases with suspected intestinal Behçet’s disease and identify potential monogenic mimics. Methods: This study is a retrospective case series. All patients underwent specialized digestive system evaluation including symptomatology, laboratory examinations, imaging, endoscopy, and pathology. Whole-exome sequencing was conducted to identify potential monogenic mimics. Results: All patients presented with prominent inflammation in the ileocecal region. A likely pathogenic de novo variant in a gene (RELA) associated with a mimicking disease phenotype was identified in one out of six patients, while a second patient had a de novo variant of uncertain significance (VUS) in RELA. A VUS in TNFAIP3 gene was identified in a third patient but was inherited from an unaffected parent. The other three patients either had no detected variant (two cases), or a very likely benign coincidental variant (in CCR1 gene). Conclusions: Monogenic autoinflammatory disorders can be mistaken for Behçet’s disease. We emphasize the importance of genetic testing in pediatric patients with intestinal Behçet’s disease who present with atypical clinical symptoms, but also the importance of using tools to estimate the likelihood of variant pathogenicity, to avoid the overinterpretation of variant significance.