A study of a cohort of HCMV serum-positive patients revealed that the expression of KIR2DL1 on NKG2C+ NK cells led to significantly larger clonal expansion than KIR2DL2, suggesting that an interaction of KIR2DL1 and HLA-C2 ligands seems to promote the expansion of NKG2C+ NK cells in response to HCMV infection (41). The gene discussed is KIR2DL1; the disease is cytomegalovirus infection.