Transiently acquired hemoglobin variants in patients with sickle cell disease: A case series and systematic review of the literature

Introduction

Patients with sickle cell disease (SCD) are transfused phenotypically-matched red blood cells (RBCs) for various indications. While screening for units that are sicklenegative is standard practice, the transfusion of RBCs containing other hemoglobin variants can be of concern to transfusion services and clinicians due to possible adverse events. Thus, this study aimed to review possible adverse events in patients with SCD with transiently acquired hemoglobin variants.

Methods

A case series of pediatric patients with SCD receiving chronic transfusions are presented, along with a systematic review of patients with SCD who were noted to have a transiently acquired hemoglobin variant. Data and patient outcomes were extracted and summarized.

Results

For the case series, 3 pediatric patients had transiently noted HbC peaks, with no adverse events documented. For the systematic review, 12 studies were included with a total of 75 patients with SCD. HbC was the most common hemoglobin variant in > 90 %. Other variants noted were: HbD, HbJ, HbD/G, HbG- Philadelphia, HbA2’, and HbO-Arab. The maximum peak of reported variants was < 20 % (14 % for HbC). No clinically significant adverse events were reported secondary to these transiently acquired variants.

Conclusion

Transiently acquired hemoglobin variants are commonly encountered in transfused patients with SCD, with no reported clinically significant adverse outcomes. Because phenotypic matching prioritizes donors with similar racial backgrounds, it increases the likelihood that the donor may carry hemoglobin variants. Blood centers and transfusion services should be aware of this phenomenon and avoid deferring donors with nonsickle hemoglobin variants.