Glucose-6-Phosphate Dehydrogenase Deficiency in Blood Donors Is Associated with Decreased Post-Transfusion Red Cell Recovery

Background:

Pre-transfusion refrigerated storage of red cells (RBCs) induces a series of metabolic and structural changes in stored RBCs (i.e., the "storage lesion"). The resulting, progressive, time-dependent decrease in RBC quality leads to decreased post-transfusion RBC recovery (PTR). Markers of oxidative stress increase during storage, suggesting the possibility that oxidative stress may be a key contributor to the storage lesion. Glucose-6-phosphate dehydrogenase (G6PD) deficiency, an X-linked condition, decreases the ability of RBCs to withstand oxidative stress by compromising their ability to synthesize NADPH. Therefore, we hypothesized that RBCs from G6PD-deficient donors would have inferior storage quality, as compared to RBCs from G6PD-normal (i.e., control) donors.

Aims:

This study examined whether G6PD deficiency, the most common enzyme deficiency worldwide, which impairs the RBC response to oxidative stress, also decreases RBC storage quality.

Methods:

Male volunteers were screened for G6PD deficiency by enzymatic assay, and next generation sequencing was performed to identify the G6PD variant in deficient subjects. In addition, participants were screened for the presence of hemoglobin variants and thalassemia by high performance liquid chromatography and complete blood count. Twenty seven control and 10 G6PD-deficient volunteers each received informed consent, donated 1 unit of leukoreduced RBCs that was stored in AS-3 under standard blood banking conditions, and completed an autologous 51-Chromium-labeled PTR study after 40-42 days of storage. Hemolysis rate in the transfused unit was measured on the day of the PTR study using a Drabkin assay. Results for control and G6PD-deficient PTRs and hemolysis rates were compared using unpaired t-tests.

Results:

A total of 145 males were screened for G6PD deficiency, yielding 15 deficient (10%) and 130 G6PD normal control (90%) subjects. Twenty seven control (G6PD normal) and 10 deficient participants who did not have hemoglobin variants or microcytosis completed the study. All blood donors met the hemoglobin acceptance criteria for autologous whole blood donation of at least 11.5 g/dL. G6PD gene sequencing of the 10 enrolled G6PD-deficient subjects identified the A- variant in 9 volunteers and the Mediterranean variant in 1. The autologous mean 24-hour PTR for control RBC units was 86.8 ± 2.8% (mean ± SD). The autologous mean 24-hour PTR for G6PD-deficient RBC units was 81.0 ± 7.2% (mean ± SD), which was significantly lower than that for control RBCs (p=0.001). None of the control volunteers (0/27) had PTR results below 75%, one of the key FDA acceptability criteria for stored RBCs. In contrast, two G6PD-deficient volunteers (2/10) had PTR results below 75% (i.e., 68.8% and 70.1%). There was no association between enzymatic G6PD activity and PTR when adjusted for G6PD status (i.e., among control or G6PD-deficient subjects, the enzymatic G6PD activity did not predict PTR). Finally, there was no difference between control and deficient RBC units in mean in vitro hemolysis rates at the end of storage (0.29 ± 0.18% vs. 0.24 ± 0.07%, respectively; p=0.38)

Conclusions:

This is the first report of the effect of G6PD deficiency on the storage quality at outdate of transfused donor RBCs stored in AS-3 additive solution as assessed by PTR, the FDA gold standard. These results demonstrate that the storage quality of G6PD-deficient RBCs is inferior to G6PD-normal RBCs. In particular, based on the FDA criteria that acceptable RBC units should have a 24-hour PTR of ≥75% at the end of storage, RBC units from G6PD-deficient donors had a 20% failure rate. The clinical consequences of the mean 5.8% decreased PTR of G6PD-defcient RBC units remain to be determined. Patients with sickle cell disease often require lifetime transfusions and up to 12.3% of phenotypically-matched RBC units utilized in their care may be G6PD-deficient. Thus, these data raise the question of whether there is value in screening blood donors for G6PD deficiency, particularly in the setting of chronic transfusion therapy, such as for patients with sickle cell disease and thalassemia.