Compared with normal NK cells, the main characteristics of ANKL cells are: CD7-/+het, CD16+dim/-, CD56+bri, CD57-, CD94+bri, HLA-DR+, Granzyme B+het/-, Perforin+ het/-, KIRs-, Ki-67+ or PD-1+ or CD30+, abnormal expression of CD45RA and CD45RO. The gene discussed is PRF1; the disease is aggressive NK-cell leukemia.