Meningococci are a type of bacteria. They can cause severe infections, including bloodstream infections (sepsis) and infection of the membranes around the brain and spinal cord (meningitis). Antibiotics can fight these infections. However, even with treatment, outcomes in patients with meningococcal disease vary widely. Several factors, including genes, probably affect outcomes. For example, patients who die may have very high levels of certain proteins that promote inflammation. These proteins are called cytokines. Genes affect whether the cytokines are released. The particular forms of genes that affect cytokine release and outcomes in patients with meningococcal disease are not well studied.