Interestingly, although glucose uptake is significantly increased in the SCD Berkeley mouse erythrocytes compared to normal, which agrees with previous studies done in human SCD erythrocytes5, there was no difference between SCD and SCD/Sphk1−/− or WT and Sphk1−/− erythrocytes (Supplementary Fig. 3a), indicating that differences in PPP and glycolysis pathways in SCD and SCD/Sphk1−/− erythrocytes are not caused by variation in glucose uptake. Here, SPHK1 is linked to Schnyder corneal dystrophy.