NKG2D expression on the surfaces of NK cells was reduced in SLE patients compared to healthy controls [51], and there was a significant negative correlation between the expression of this receptor and SLE Disease Activity Index (SLEDAI) scores, disproving the previous conclusion [52] that “NKG2D is unlikely to play a key role in the pathogenesis of lupus” [53]. The gene discussed is KLRK1; the disease is systemic lupus erythematosus.