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BACKGROUND: Pyogenic liver abscess is an uncommon pediatric condition, and represents a rare causative agent in otherwise healthy children. Such infections may signal an underlying inborn error of immunity. Alpha-1 antitrypsin (A1AT), encoded by the gene, is a serine protease inhibitor with key immunomodulatory functions. In mouse models, A1AT prevents degradation of the antimicrobial SPLUNC1 protein to enhance host defense against . In humans, while A1AT variants can be associated with a generally increased risk of respiratory infection, to our knowledge no corresponding impact with respect to has been reported.CASE DESCRIPTION: We report a previously healthy 14-month-old girl who developed liver abscess without identifiable predisposing factors. Comprehensive immunologic evaluation was unremarkable except for whole exome sequencing revealing homozygous S allele pathogenic variant (c.863 A>T, p.E288V) known as the S allele associated with partial A1AT deficiency. The clinical presentation, microbiologic findings, and disease course suggested that defective A1AT function may have contributed to dysregulated inflammation and susceptibility to infection.CONCLUSION: This case highlights a potential association between homozygosity in the pathogenic S variant of and susceptibility to severe , in this case liver abscess. While A1AT deficiency is classically associated with pulmonary and hepatic disease, the immunomodulatory role of A1AT suggests broader relevance in host defense. Early recognition of underlying defects in children with unusual or severe infections may inform prognosis, guide management, and prompt appropriate genetic counseling and surveillance for long-term complications.