RT Journal Article T1 Inborn Error of STAT2-Dependent IFN-I Immunity in a Patient Presented with Hemophagocytic Lymphohistiocytosis and Multisystem Inflammatory Syndrome in Children A1 López-Nevado, Marta A1 Sevilla, Julián A1 Almendro-Vázquez, Patricia A1 Gil-Etayo, Francisco J. A1 Garcinuño, Sara A1 Serrano-Hernández, Antonio A1 Paz Artal, Estela Natividad A1 González Granado, Luis Ignacio A1 Allende Martínez, Luis Miguel AB Human inborn errors of immunity (IEI) affecting the type I interferon (IFN-I) induction pathway have been associated with predisposition to severe viral infections. Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening systemic hyperinflammatory syndrome that has been increasingly associated with inborn errors of IFN-I-mediated innate immunity. Here is reported a novel case of complete deficiency of STAT2 in a 3-year-old child that presented with typical features of HLH after mumps, measles, and rubella vaccination at the age of 12 months. Due to the life-threatening risk of viral infection, she received SARS-CoV-2 mRNA vaccination. Unfortunately, she developed multisystem inflammatory syndrome in children (MIS-C) after SARS-CoV-2 infection, 4 months after the last dose. Functional studies showed an impaired IFN-I-induced response and a defective IFNα expression at later stages of STAT2 pathway induction. These results suggest a possible more complex mechanism for hyperinflammatory reactions in this type of patients involving a possible defect in the IFN-I production. Understanding the cellular and molecular links between IFN-I-induced signaling and hyperinflammatory syndromes can be critical for the diagnosis and tailored management of these patients with predisposition to severe viral infection. SN 0271-9142 SN 1573-2592 YR 2023 FD 2023-04-19 LK https://hdl.handle.net/20.500.14352/114117 UL https://hdl.handle.net/20.500.14352/114117 LA eng NO López-Nevado M, Sevilla J, Almendro-Vázquez P, Gil-Etayo FJ, Garcinuño S, Serrano-Hernández A, Paz-Artal E, González-Granado LI, Allende LM. Inborn Error of STAT2-Dependent IFN-I Immunity in a Patient Presented with Hemophagocytic Lymphohistiocytosis and Multisystem Inflammatory Syndrome in Children. J Clin Immunol. 2023 Aug;43(6):1278-1288. doi: 10.1007/s10875-023-01488-6. Epub 2023 Apr 19. PMID: 37074537; PMCID: PMC10113994. DS Docta Complutense RD 7 abr 2025