INTRODUCTION: The incidence of Inborn Errors of Immunity (IEI) has increased in the last years. The aim of this study is to characterize the different subcategories of IEI in a pediatric hospital in Chile.

METHOD: A retrospective, descriptive study with a non-probabilistic selection model in a public tertiary pediatric hospital in Santiago, Chile. Children under 18 years old with a confirmed diagnosis of IEI between 2001 and 2022 were included, classified according to the International Union of Immunological Societies (IUIS) 2022 criteria.

RESULTS: 138 patients were included, with a mean age of 3.12 years. The male:female ratio was 1.5:1. Antibody deficiency disorders were the most frequent (41%), followed by Combined immune deficiencies (CIDs) with associated or syndromic features (23%) and immune dysregulation diseases (8.7%). No IEI patients were described in IUIS VIII, IX and X groups. In our center “Bone Marrow Failure” are exclusively followed by hematologist. Less than 1% had a history of consanguinity and 12% had a family history of IEI. 85.5% had infections, of which the most frequent were pneumonias, 53% presented atopy, 35% autoimmunity, 15% lymphoproliferation and 3.7% a history of neoplasia. 47/138 (34%) of the patients had a genetic study mostly since 2015 (43/47) due to an increase of access. 25 patients (18%) have been presented as candidates for hematopoietic stem cell transplantation (HSCT), of which 15 have been transplanted. In this group, 53% correspond to severe combined immunodeficiency (SCID), with an average age of the procedure of 0.6 years. Five of those patients had a genetic study: IL2RG (1), IL7Rα (1), RAG-2 (2) and Artemis (1). One patient underwent gene therapy.

CONCLUSIONS: In our study, we described an increase of the diagnosis of IEI. The age of presentation was early and antibody deficiency disorders were the most frequent as describe in the literature.