Genetic Profile of Inborn Errors of Immunity Using Whole Exome Sequencing in Individuals With BCG Localized Adverse Events

Purpose: In Mycobacterium tuberculosis endemic regions, BCG vaccine is administered early after birth to confer protection against severe form of tuberculosis disease. Previous reports suggest that BCG adverse events, even localized ones (BCGitis), can be the first manifestation of immunodeficiency. We investigated children with a history of BCGitis who needed drug treatment looking for possibly pathogenic variants in inborn errors of immunity genes (IEI-genes). Methods: Forty-four probands were evaluated. The exome sequences obtained by Next-Generation Sequencing were filtered for variants in the 344 IEI-genes described by the International Union of Immunological Societies (IUIS) and classified according to the recommendations of the American College of Medical Genetics. The identified candidate variants were validated by Sanger sequencing. Results: Out of the 44 probands, 36 were sporadic cases and 8 were familial cases. Thirty-one in 44 (70.5%) presented immunoallergic or other infectious clinical conditions besides BCGitis; 19 in 44 (43.2%) presented variants classified as pathogenic or likely pathogenic in 17 different IEI-genes, of which 35.3% were genes related to defects in intrinsic and innate immunity, including Mendelian Susceptibility to Mycobacterial Disease (MSMD) genes (IRF8, IFNGR1, JAK1, STAT1, TLR3 and TBK1). Remaining genes were distributed in another five IUIS classifications groups (CARD14, CFH, CHD7, FOXN1, NFAT5, NLRP3, NOD2, PMS2, STAT3, TNFRSF13B and TNFSF12). Conclusion: The high prevalence of pathogenic or likely pathogenic variants found in IEI-genes may be associated with BCGitis, which should be considered a sign of an inborn error of immunity.