Eosin-5′-maleimide (EMA)-binding assay as a diagnostic method of hereditary spherocytosis

Objectives Erythrocyte membrane disorders are caused by a deficiency of structural proteins in the erythrocyte membrane. Accurate differential diagnosis within this group of disorders (is essential for appropriate management. The eosin-5′-maleimide (EMA) binding assay is a novel test that is used for the differential diagnosis of erythrocyte membrane disorders. In this study, we have examined and reported blood counts, reticulocyte indices, and the EMA binding assay results with clinical findings of cases admitted to our laboratory for suspected red blood cell (RBC) membrane disorder. Methods We performed the EMA binding assay on the blood samples of 103 patients who were screened for hereditary erythrocyte membrane disorders at the Flow Cytometry Laboratory of Ankara Numune Training and Research Hospital. The total cohort was grouped as patients with hereditary spherocytosis (HS) (n=36) and control group (patients without erythrocyte membrane disorders (n=60), and non-HS patients with a preliminary diagnosis of hemolytic anemia (n=7). The control group included during data collection, the results of the EMA binding assay were recorded along with demographic features, clinical information, morphologic features, blood count parameters, RBC and reticulocyte indices, and a conventional osmotic fragility (OF) test. Receiver Operating Characteristics (ROC) analyses were performed to evaluate the diagnostic accuracy of the EMA binding assay and reticulocyte parameters. Results Both EMA testing and flow cytometric (FC) OF test were significantly lower in overall (n=36), ≤10-year-old (n=12), and >10-year-old (n=24) patients with HS than in healthy controls (p<0.001). The EMA binding assay had 100 % sensitivity and specificity in screening HS. Conclusions Combined with conventional blood tests, clinical findings, and medical history, the EMA binding assay is a reliable and convenient tool for screening for HS and differentiating hereditary erythrocyte membrane disorders.