Both NK1.1 and CD244 are aberrantly expressed on Ebf1+/– pro-B and CD25– pre-B cells.14 In contrast, several EB primary tumor cell isolates strongly displayed both CD25 and CD244, likely indicating they had progressed to the late pre-B stage before transformation occurred and CD244 expression was further upregulated. The gene discussed is IL2RA; the disease is epidermolysis bullosa.