Human genetic resistance to malaria refers to inherited changes in the DNA of humans which increase resistance to malaria and result in increased survival of individuals with those genetic changes. The existence of these genotypes is likely due to evolutionary pressure exerted by parasites of the genus Plasmodium which cause malaria. Since malaria infects red blood cells, these genetic changes are most commonly alterations to molecules essential for red blood cell function (and therefore parasite survival), such as hemoglobin or other cellular proteins or enzymes of red blood cells. These alterations generally protect red blood cells from invasion by Plasmodium parasites or replication of parasites within the red blood cell.