Longitudinal G6PD activity recovered from three cryopreserved aliquots of the same specimen. Data are shown for four specimens, three with normal G6PD activity and one with deficient G6PD activity. Specimens were cryopreserved at a single date in multiple aliquots. Aliquots of cryopreserved specimens were than thawed at multiple dates and analysed for G6PD activity. (A) Absolute G6PD activity at thaw dates after cryopreservation and (B) Difference in G6PD activity from that at Day 0. For easy comparison the dates were normalized to Days 1, 2, and 3 in Figure 2B.