Background <p>Deficiency in <i>ELF4</i>, X-linked (DEX) is a recently recognized monogenic autoinflammatory disorder and a novel type of congenital immunodeficiency. Due to the limited number of reported cases, understanding of DEX remains incomplete. In clinical settings, children with this condition are often misdiagnosed as having diseases such as Behçet’s disease or inflammatory bowel disease, due to overlapping clinical features.</p> Methods <p>Genomic DNA was isolated from peripheral blood samples for genetic analysis, and genomic DNA was extracted from the peripheral blood samples of the proband’s mother for x chromosome inactivation (XCI) analysis.</p> Results <p>A retrospective analysis was conducted on the clinical and genetic characteristics of a 3-year-old male patient with DEX in China. This study offers a detailed exploration of the child’s specific clinical symptoms and treatment approach, in addition to a comprehensive review of the primary clinical manifestations and genotypic traits of individuals with DEX.</p> Conclusion <p>This study aims to increase clinicians’ understanding of DEX. In cases where young male patients present with recurrent fever, oral or mucosal ulcers, or repeated infections, DEX should be strongly considered. Early implementation of gastrointestinal endoscopy and genetic testing is recommended to enable a more precise and timely diagnosis, laying a solid foundation for informed treatment decisions.</p>