In HCMV-uninfected donors, there are roughly equal proportions of CD57+NKG2C+ and CD57−NKG2C+ NK cells whereas the ratio of CD57+NKG2C+ to CD57−NKG2C+ NK cells ranges from <1 to >60 in HCMV-infected donors (99); whether this variation reflects varying duration of HCMV infection is not known. The gene discussed is KLRC2; the disease is cytomegalovirus infection.