Abstract: Abstract Objective:NFKB1 deficiency will result in a variety of clinical and immunological features. EpsteinBarr virusinduced disease is a rare phenotype. We report the case to expand the spectrum of this disease. Methods:We analyzed clinical manifestations and physical signs of one patient with NFKB1 deficiency and performed immunological evaluation, Lymphocyte subpopulation, Whole exome sequencing (WES), Sanger sequencing, Realtime PCR and Western blot. Results:The patient is a 12year-old female. She suffered from a recurrent fever for six months. She was diagnosed with dysfunction of blood clotting, hepatic function damage, hepatosplenomegaly and lymphadenopathy accompanied with high titer of EBV and significantly increased NK cell. WES showed that she carried the NFKB1 gene de nove mutation: c.2430 dupA. Its site had not been reported before. Different from previous reports, the mutation was located in the death domain of the protein, which may lead to an early termination of amino acid. Functional experiment showed decreased p50 expression and unstable mRNA. Conclusion:NFKB1 deficiency could be diagnosed by combining clinical and immunological features with genetic phenotypes. We expanded the clinical and genetic phenotypes of this disease.