Objective: Inborn errors of immunity (IEI) represent a heterogeneous and expanding group of disorders with a broad clinical spectrum extending beyond recurrent infections. This study aimed to evaluate the demographic, clinical, and immunological characteristics of adult patients referred with suspicion of IEI.
Materials and Methods: In this single-center retrospective observational study, the medical records of 433 patients referred to the Immunology and Allergy outpatient clinic between January 2021 and December 2022 with symptoms suggestive of IEI were retrospectively reviewed.
Results: The most common presenting complaints were frequent respiratory tract infections, skin/mucosa findings like delayed wound healing or oral aphthous ulcers, family history of IEI, diarrhea, uncontrolled severe asthma, and frequent urinary tract infections. Decreased serum IgG, IgM, and IgA levels were observed in 11.3% (n=49), 10.4% (n=45), and 14.1% (n=61) of the patients, respectively. Reduced IgG subclass levels were detected as follows: IgG1 in 6.7% (n=29), IgG2 in 10.6% (n=46), IgG3 in 3.7% (n=16), and IgG4 in 6% (n=26). Flow cytometric analysis revealed decreased CD19+ B cell counts in 20.3% (n=88), CD4+ T cell counts in 10.4% (n=45), CD8+ T cell counts in 6.9% (n=30), CD16+ natural killer (NK) cell counts in 15.2% (n=66), and CD56+ NK cell counts in 11.1% (n=48) of the patients. Selective IgA deficiency was identified in 24 patients, selective IgM deficiency in 15, IgG subclass deficiency in 22, and isolated IgG deficiency in 20 patients. Following comprehensive immunological evaluation, 21 of the 433 patients (4.8%) were newly diagnosed with IEI and immunoglobulin replacement therapy was initiated.
Conclusion: Although most patients presenting with signs suggestive of immune dysfunction do not ultimately receive a diagnosis of IEI, a meaningful proportion can still be identified through appropriate immunological evaluation. These findings emphasize the importance of interpreting laboratory abnormalities together with both infectious and non-infectious clinical manifestations in the diagnostic assessment of suspected immunodeficiency.