We have shown that the expression of the genes KLRB1, KLRC1, KLRD1, KLRF1 is consistently decreased in MI, that is in a good accordance with the study by Yan et al. [26], where a loss of NK cell activity was found in patients with acute MI, in particular, due to a decrease in KLRB1 expression. The gene discussed is KLRF1; the disease is myocardial infarction.