Allogenic hematopoietic stem cell transplantation (HSCT) is often performed for patients with acute lymphoblastic leukemia and acute myelogenous leukemia, chronic myelogenous leukemia and chronic lymphocytic leukemia, Non-Hodgkin's lymphoma and Hodgkin's lymphoma, multiple myeloma, aplastic anemia, sickle cell disease and thalassemia. Killer cell immunoglobulin like receptors (KIRs) found on natural killer (NK) cells, and their HLA-ligands are important determinants for allogenic HSCT. Researchers at St. Jude found that variations in the genetic structure of the KIRs result in functional differences in NK cells and developed an expedient method for identifying optimal donors. The single-nucleotide polymorphism (SNP) assay types various allele groups of KIR2DL1 with distinct functional properties based on polymorphism at position 245. They also established a SNP assay to type different KIR ligands based on polymorphism at position 77 in HLA-C and position 83 in HLA-B and -A. In addition to providing valuable information about a potential donor, these SNP assays for KIR and KIR ligand typing are much cheaper and faster than existing high-resolution typing.