Pb2036: peripheral blood cytopenia, an early indicator of inborn errors of immunity

Topic: 11. Bone marrow failure syndromes incl. PNH - Biology & Translational Research Background: Inborn Errors of Immunity (IEI) are inherited monogenic disorders resulting in defective immune response. Non-infectious presentations are increasingly more apparent. Widely available, cost-effective early indicators are needed. Peripheral blood cytopenia may be a presenting laboratory feature or observed secondary phenomenon. Aims: This retrospective review of the South African Primary Immunodeficiency Registry (SAPIDR) aimed to assess the haematological indices at presentation; their association with International Union of Immunological Societies (IUIS) 2019 classification and mortality. Methods: Haematological indices of patients on the SAPIDR were retrospectively reviewed. Presentation with cytopenia and the associated with molecular diagnosis and outcome was analysed. Results: Of 396 patients on the SAPIDR, 66% (n=257) had available haematological results. Sixty percent were males and 85% under 18 years. The median age at diagnosis was 76 months (range from birth to 420 months). None were from a consanguineous relationship and 27% had a known family history of IEI. Majority (53%) had predominantly antibody deficiency. At presentation, infection was prominent (86%) followed by cytopenia (62%). Neutropenia was associated with IUIS III [Odds Ratio (OR) 3.65 Confidence interval (CI) (1.44-9.25)], thrombocytopenia with IUIS II [OR 14.39 CI (2.89-71.57)], lymphopenia with IUIS I [OR 12.16 CI(2.75-53.73)] and pancytopenia with IUSI I [OR 12.24 CI (3.82-39.05)] and IUIS II [OR 5.99 CI (2.80-12.76)]. Molecular diagnosis was confirmed in 30% where cytopenia at presentation [OR 2.26 (1.42-3.59)] namely persistent cytopenia [OR1.86 (1.06-3.26)] were predictive. Cytopenia showed shorter overall survival [OR 2.81 CI (1.288-4.16)]. Summary/Conclusion: Cytopenia(s) that are severe, persistent, unusual and/or recurrent should prompt further investigation for IEI. The full blood count and leucocyte differential, may facilitate earlier identification and serve as an adjunct to definitive molecular classification. Keywords: Immunodeficiency, Immunity, Pancytopenia