Stat1, short for Signal transducer and activator of transcription 1, is a latent cytoplasmic transcription factor. It is a crucial component in multiple signaling pathways, especially those activated by type I, II, and III interferons, as well as interleukin-27 [1]. STAT1 plays a key role in the immune response against viruses and other pathogens by transducing signals to the nucleus from these cytokines, and then activating the transcription of numerous genes, some with well-characterized antiviral properties [2].

STAT1 gene deletion in mice (a form of gene knockout model) causes rapid death from severe infections, highlighting its vital role in the immune response [2]. In addition, inborn errors of human STAT1 immunity, which can be due to various loss-or gain-of-function mutations, underlie 4 distinct disorders: autosomal recessive (AR) complete and partial STAT1 deficiency, autosomal dominant (AD) STAT1 deficiency, and AD STAT1 gain-of-function [1,3]. These genetic alterations lead to different clinical manifestations, reflecting the complex roles of STAT1 in the host immune system.

In conclusion, Stat1 is essential for the immune response against pathogens, especially viruses. Studies using gene knockout mouse models have revealed its critical role in host defense, and understanding the function of Stat1 in different disease-related genetic mutations provides insights into the mechanisms of various immune-related disorders.