Broken cells and hidden genes: Detection of <scp> <i>SLC4A1</i> </scp> variant of hereditary spherocytosis in a blood donor

During component preparation, plasma separated using the platelet-rich plasma (PRP) method (2035 relative centrifugal force [rcf] for 9 min) showed gross hemolysis (3.47%). Components were processed within 6 h of blood collection. Root-cause analysis (RCA) ruled out equipment-related or processing errors (Figure 1). Blood culture and the anti-globulin test excluded sepsis or immune hemolysis. The donor pilot tube (1490 rcf for 3 min) showed clear plasma which hemolyzed when recentrifuged at 3350 rcf for 3 min suggesting mechanical hemolysis and prompting investigation into donor red cell abnormalities (Figure 2). The donor, a first-time young male without a history of jaundice/anemia/drug intake had a pre-donation hemoglobin (Hb) of 12.6 g/dL (Hb cut-off as per Indian regulation is ≥12.5 g/dL).1 Post-donation values were Hb-11.3 g/dL, platelet count 261 × 103/μL, MCV 96.3 fL, MCH 30.6 pg, MCHC 31.7 g/dL, and the peripheral blood smear showed numerous spherocytes (Figure 3). Glucose-6-phosphate dehydrogenase screen was negative, and hemoglobin high-performance liquid chromatography was normal. Osmotic fragility test showed increased RBC fragility, and eosin 5′maleimide indicated a significant reduction in dye binding, suggesting hereditary spherocytosis (HS).2 Clinical exome sequencing identified a missense variant in SLC4A1 protein (also known as band 3 or anion exchanger 1, AE1) classified as likely pathogenic in ClinVar database.3 The donor was diagnosed with HS type 4 (Autosomal Dominant) and advised to refrain from future blood donations. Mild or benign HS variants have been reported in blood donors which were identified through osmotic fragility tests.4 Further, red cells from HS donors have shown increased osmotic fragility during storage as evident by a decrease in post-transfusion survival by the fourth week of storage.5 However, in the present case, mechanical hemolysis was observed while components were being prepared indicating the increased susceptibility of the red cells to mechanical stress. Also, a concomitant iron deficiency (as indicated by low to normal MCHC) could not be ruled out considering the high frequency of iron deficiency in the Indian population.6 Iron deficiency was not investigated as the donor was a first-time donor and was not anemic before blood donation. Mild or minor hereditary spherocytosis is reported to occur in approximately 20–30% of patients of HS where Hb is typically maintained within the near-normal range (11–15 g/dL).7 The present case highlights the importance of donor factors for component quality as well as their consideration in the RCA for component quality-related issues even in an apparently healthy donor. Identification of donor factors may have implications for both donor safety and patient outcomes. HCP, GP, PC, and GKV contributed to conceptualization and resource provision. SS and HCP conducted data curation, formal analysis, and manuscript writing. HCP and GKV contributed to conceptualization and resource provision. SS and HCP conducted data curation, formal analysis, and manuscript writing. The authors declare no conflicts of interest. All data supporting the findings of this study are available within the paper.