[Genetic analysis of a child with X-linked familial Behcet-like autoinflammatory syndrome-2 due to variant of ELF4 gene].

Objective: To explore the clinical and genetic characteristics of a boy with X-linked familial Behcet-like autoinflammatory syndrome-2 (AIFBL2).

Methods: A boy who was admitted to Children's Hospital Affiliated to Zhengzhou University in December 2023 due to recurrent oral ulcers for 2 years, intermittent abdominal pain and fever for more than 1 year was selected as the study subject. Clinical data of the patient was collected. Whole exome sequencing (WES) was carried out, and candidate variant was verified by Sanger sequencing and bioinformatic analysis. A literature search was conducted in OMIM, PubMed, Wanfang Data Knowledge Service Platform, China Biomedical Literature Service System, and the VIP database using the keywords "ELF4 gene" "deficiency in ELF4, X-linked" "ELF4 deficiency" and "DEX" to identify recently published studies. This study was approved by the Medical Ethics Committee of the Children's Hospital Affiliated to Zhengzhou University (Ethics No.: 2023-H-K44).

Results: The patient, a 12-year-old male, presented with recurrent mouth ulcers, fever and abdominal pain. Lymphocyte subsets showed a significant decrease in NK cells. Abdominal CT showed thickening of local intestinal wall in the lower right abdomen. Colonoscopy revealed a solitary deep longitudinal ulcer in the ileocecal region. Genetic testing revealed a hemizygote missense variant c.687C>G, with his mother showing the same mutation at this locus. According to the guidelines of the American College of Medical Genetics and Genomics (ACMG), the variant was considered likely pathogenic (PP1+PP2+PM2_Supporting+PP3+PP4). Literature review has found 19 AIFBL2 patients including 1 patient from this study. Mouth ulcer, fever, rash and abdominal pain were the primary clinical manifestations, for which genetic testing is the main diagnostic method.

Conclusion: The hemizygote c.687C>G missense variant of the ELF4 gene probably underlay the AIFBL2 in this child, which has provided a basis for his clinical diagnosis and genetic counseling.