Clinical Implications of ZNFX1 Mutation in Interferonopathy: A Case Study

Interferonopathies are complex inborn errors of immunity characterized by dysregulation of interferon signaling pathways. They lead to excessive immune responses and systemic inflammation. This case report describes an infant with cytopenia and severe viral illness presented as hemophagocytic lymphohistiocytosis (HLH)-like features caused by a mutation in the ZNFX1 gene, a significant cause of type 1 interferonopathy. Case Scenario This case study presents a unique instance of a ZNFX1-related interferonopathy in a 6-month-old boy, a nonidentical twin, with a novel homozygous mutation (c.1928G>A, p.Trp643X) identified following cytomegalovirus infection. The patient exhibited classic HLH features, including recurrent fevers, pancytopenia, elevated inflammatory markers, and high serum ferritin levels. The mutation in ZNFX1, a critical gene encoding a helicase protein integral to viral infection recognition, disrupted normal interferon regulation and immune response mechanisms. Genetic testing revealed autosomal recessive inheritance, with both parents heterozygous for a ZNFX1 gene variant. And no mutation was detected in his twin brother. Treatment options employed included steroids, intravenous immunoglobulin (IVIG), and Anakinra, an IL-1 receptor antagonist. Despite these interventions and plans for hematopoietic stem cell transplantation, the patient developed a severe CMV infection, and he died before transplantation. Conclusion This case underscores the importance of genetic evaluation in diagnosing complex immunological disorders, highlighting the need for comprehensive management and early intervention in ZNFX1-related interferonopathies. The findings contribute to the growing understanding of genetic factors underlying immune dysregulation and provide insights into potential therapeutic approaches for similar pediatric immunological conditions.