Myeloperoxidase deficiency: a single center experience

Abstract

Aim: Myeloperoxidase (MPO) deficiency is the most common inherited defect of phagocytes. In this article, we aimed to reveal clinical characteristics of our patients with primary MPO deficiency.
 Material and Method: In our study, patients aged 0-18 years, who were consulted to Ankara City Hospital Pediatric Hematology Department between 1 October 2019 and 1 December 2021 due to neutropenia, were retrospectively examined. If a patient had neutropenia in the complete blood count and inconsistently normal neutrophil count in the peripheral blood smear formula it was accepted as pseudoneutropenia. Patients with pseuduneutropenia were included in the study.
 Results: Fifteen patients diagnosed with MPO deficiency were analyzed in the study. Nine of the patients were female, 6 were male, median age of the patients was 7 (0 – 17.5) years. The mean white blood cell (WBC) count of the patients was reported as 8219±2879/mm3, and the mean neutrophil count and percentage in the complete blood count printout was 33.30±15.88/mm3 and 0,74%±0, 94% respectively. The mean neutrophil count and percentage counted in the peripheral blood smear were 5186±1710 and 63.8%±10.59%, respectively. The mean LUC value on the complete blood count printout was 54.35%±19.47% (Normal range, 0-4%). In the flow cytometry evaluation of peripheral blood samples of the patients, it was observed that neutrophils were stained with CD33, CD13, CD16, CD11b monoclonal antibodies but not with MPO.
 Conclusion: Peripheral smear evaluation is important when investigating the etiology of neutropenia. Many hematology analyzers using the MPO staining technique are indicative of MPO deficiency by identifying large unstained cells that do not stain with MPO. In patients who present with recurrent infections and MPO deficiency, other reasons that may predispose to infections should be investigated.