A nonsense mutation in IKBKB causes combined immunodeficiency.

Area of Science:

• Immunology
• Genetics

Background:

• Primary immunodeficiencies (PIDs) are a group of genetic disorders affecting the immune system.
• Identifying the molecular basis of PIDs provides crucial insights into immune system development and function.

Observation:

• Four patients from two consanguineous Qatari families presented with similar clinical and immunological features of combined immunodeficiency.
• Patients exhibited recurrent fungal, viral, and bacterial infections, hypogammaglobulinemia, reduced regulatory T-cells and NK-cells, and naive T-cells with impaired activation.

Findings:

• Whole-exome sequencing identified a homozygous nonsense mutation (R286X) in the IKBKB gene in all affected patients.
• The mutation resulted in undetectable IKKβ protein and severely decreased NEMO protein levels.
• Mutant IKKβ(R286X) could not form complexes with IKKα/NEMO, leading to impaired IκBα phosphorylation and NFκB nuclear translocation in patient B cells.

Implications:

• This study identifies a novel genetic cause of combined immunodeficiency due to a mutation in IKBKB.
• The findings highlight the critical role of the IKKβ/NFκB pathway in adaptive and innate immunity.
• Understanding this specific molecular etiology can aid in diagnosis and potentially inform therapeutic strategies for similar immunodeficiencies.