The majority of hereditary hemochromatosis is due to inheritance of hemochromatosis gene mutations. Hemochromatosis gene mutations are common among individuals of European ancestry; however, only a small proportion of individuals with these mutations develop clinical disease. Other genetic and nongenetic factors contribute to disease expression. Hemochromatosis genotyping should only be performed among individuals with iron overload (e.g., elevated fasting transferrin saturation >45%) or a known family history of hemochromatosis-associated hereditary hemochromatosis.