A descriptive analysis of autoimmune cytopenias in children with inborn errors of immunity.

Introduction: Inborn errors of immunity (IEI) are a heterogenous group of disorders that lead to impairment and dysfunction of one or more parts of the immune system. Autoimmunity and autoimmune cytopenias have increasingly been recognized as early markers of IEI. This study describes the type, severity and range of cytopenias in children with IEI of varying immunophenotypes at a single Canadian centre. Methods: A retrospective chart review was completed of children with IEI followed at the Stollery Children's Hospital in Edmonton, Alberta from January 2015 to December 2022. Patients were included if they received a diagnosis of an IEI and had single or multi-lineage cytopenia(s). The IEI diagnoses were grouped into immunophenotypic categories and cytopenias were compared using descriptive statistics. Results: Immune cytopenias were common in all phenotypic categories, though there was variability in the type and severity. Thrombocytopenia was most likely to be seen in combined (53.8%), syndromic (59%) and immune regulatory disorders (63.6%). Neutropenia was most common in phagocytic (71.4%), immune regulatory (63.7%) and humoral disorders (52.6%). Multi-lineage cytopenias were present in 67.2% of cases and 10.4% had persistent cytopenias. Conclusions: Immune cytopenias are common in varying types of IEI and are not isolated to a specific disease category. When seeing a patient with concerns for IEI, providers should investigate both for features of immunodeficiency and autoimmunity, in particular autoimmune cytopenias. The pattern of cytopenia may favour specific immunophenotypes and help prioritize further testing and timely referral.