Genetic variations in blood donors that affect red blood cells for transfusion.

Summary

During banking of blood for transfusion, red blood cells are stored in additive solution in the cold for the duration of their shelf life and may be irradiated or ‘washed’ as standard practice for specific clinical needs. These manipulations, together with certain genetic variations in the donor, can alter the quality of red cells making them unsuitable for transfusion to certain vulnerable recipient groups. Previously, with the help of NIHRBR (study 112), we studied a relatively rare genetic variant that can cause Familial Pseudohyperkalaemia (FP). This condition is asymptomatic in the donor but when the FP red cells are cooled for storage, they leak potassium more rapidly than standard red cells. High levels of potassium in the blood unit may cause cardiac arrest when transfused at large volumes, especially in small babies. Use of ‘fresh’ red cells for infant large volume transfusion reduces the risk with standard red cell units, but ‘fresh’ FP red cell units can contain unexpectedly high levels of potassium. Our data resulted in a change in guidelines which prevents the red cell units from donors genotyped for this specific variant being transfused in infants. We have also studied the effect of irradiation on red cells with FP. The results show that FP red cells do not have higher potassium following irradiation than controls. This is an important finding as it provides assurance that red cells from FP donors are suitable for patients apart from infants.

We now want to examine the effect of ‘washing’ on FP red cells. We also want to investigate other variants that have been reported to cause FP. Our study so far has focused on the variant rs148211042 in the ABCB6 gene. There are four other variants of interest in ABCB6 that need investigation for their effect on red cell quality. It would also be of interest to determine the effect of homozygous inheritance of ABCB6 variants. We may also identify variants that result in improved red cell storage and quality, making them beneficial for transfusion to certain recipient groups.

Ultimately, we want to be able to identify these red cell variants in donors, who are themselves asymptomatic, so that these donations can be targeted to the appropriate recipient group.