GPI and aplastic anemia: It is likely that more patients with small GPI-deficient granulocyte clone sizes have been enrolled in the Registry in recent years due to improvements in disease awareness, enhanced emphasis on screening (e.g., screening for GPI-deficient cells is now routine in patients with aplastic anemia) and early detection, and the increased availability and utilization of high-sensitivity flow cytometry for detection of PNH clones [4, 6, 25, 26].