A new-disease-causing dominant-negative variant in CARD11 gene in a Chinese case with recurrent fever

Immunodeficiency 11B with atopic dermatitis (IMD11B, OMIM:617638) is rare primary immunodeficiency disease caused by germline dominant negative (DN) mutations in the CARD11 gene. Affected patients present with immune dysfunction, recurrent infections and atopic dermatitis. In this study, we sought to identify and characterize the genetic variant in one patient with periodic fever, recurrent infections, and eczema. Trio whole-exome sequencing (WES) was employed in this patient and her parents, and Sanger sequencing validated the potential pathogenic variant. In vitro functional study was performed to evaluate the pathogenicity of genetic variant identified. A very rare missense mutation (c.2324C > T, p.S775L) in CARD11 gene (NM_032415) was identified by WES in the patient but not her parents. Luciferase reporter assays and co-immunoprecipitation demonstrated mutation exerts a dominant-interfering effect on wild-type CARD11, inhibiting the activity of NF-κB. RNA sequencing analysis also confirmed that mutant CARD11 inhibited down-stream transcriptional activity of NF-κB. A review of literature doesn't found significant genotype-phenotype correlation. We identified a vary rare DN CARD11 mutation, expanding the genetic and phenotypic spectrum of CARD11.