Tumor cells often downregulate expression of MHC-I to evade T cell recognition, however, low, altered, or missing MHC-I expression exposes tumor cells to NK cell recognition as NK cells are able to distinguish between self and non-self by binding with MHC-I through highly polymorphic receptors known as Ly49s in mice, and killer cell immunoglobulin-like receptors (KIRs) in humans. The gene discussed is KIR3DL2; the disease is neoplasm.