Evaluation of a Child with Suspected Inborn Error of Immunity

Inborn errors of immunity (IEI), which includes primary immunodeficiencies, are a heterogenous group of disorders that affect the immune system leading to infections, autoimmunity, atopy, inflammation, or malignancy. The most recent update by Inter-national Union of Immunological Societies (IUIS) reports more than 500 gene defects in 10 categories. The initial approach to diagnosis should be dictated by the clinical history and physical examination. Traditional laboratory studies and genetic testing represent the backbone of diagnostic testing. The treatment options depend on the specific disorder and include support measures, immunoglobulin replacement therapy, antibiotic prophylaxis, immunosuppression, biological therapy, hematopoietic stem cell transplantation, and gene therapy. The early clinical suspicion and expeditious testing contribute to im-proved outcomes. This review provides a general approach to patients with suspected IEIs, highlighting aspects of infections and non-infectious manifestations, clinical history, physical examination, and immune laboratories, functional and genetic evaluation.