The strong inhibitory <i>KIR2DL1*00201</i>+<i>C2</i> interaction reduced ALL risk (<i>p</i> = 0.01), while <i>KIR2DL1*00302</i> +<i>C2</i> (<i>p</i> = 0.008), <i>KIR2DL3*00201</i>+<i>C1</i> (<i>p</i> = 0.03), and <i>KIR3DL1*00501</i>+<i>Bw4 80I</i> (<i>p</i> = 0.008) interactions protected against AML (<i>p</i> < 0.05). The gene discussed is KIR2DL1; the disease is acute lymphoblastic leukemia.