Background: The Nuclear Factor-kappa B (NF-kB) signaling pathway plays a critical role in regulating a wide range of cellular processes such as immune function, inflammation, and tumor regulation. There are two major pathways that play a role in NF-kB activation: the canonical NF-kB1 pathway and the non-canonical NF-kB2 pathway. Abnormalities in non-canonical NF-κB2 signaling are linked with significant impairments in the immune system, mainly B cell maturation, antibody production, as well as T helper and regulatory T cell function through its effect on germinal center regulation.Methods: Our patient’s medical record was analyzed retrospectively, including her medical history, results from immune laboratory tests, and genetic analyses.Results: We present a 16-year-old female with a history of chronic cough complicated with episodes of hemoptysis and diagnosed with bronchiectasis secondary to common variable immunodeficiency. Whole exome sequencing analysis revealed a novel heterozygous variant in the NFKB2 gene (NM_001077494.3), c.931C>T resulting in p.Arg311Cys.Conclusion: The presence of NFKB2 mutations can lead to the development of early-onset common variable immunodeficiency.Statement of Novelty: We have identified a novel variant in the NFKB2 gene associated with antibody deficiency.

Severe combined immunodeficiency (SCID) is caused by critical genetic defects affecting the immune system. Early diagnosis and intervention are essential for preventing life-threatening infections, end-organ damage, and complications. Newborn screening for SCID is currently performed in many provinces and territories across Canada. The SickKids Newborn Screening Centre in Toronto, Ontario, is a quaternary referral centre that has evaluated SCID newborn screen-positive infants since the program’s introduction in 2013. Here, we provide updated algorithms for clinical investigation and follow-up of infants with an initial positive screen.Statement of novelty: We provide algorithms for the clinical follow-up of SCID newborn screen-positive infants at a quaternary referral centre.