Hereditary hemochromatosis (iron overload) is a genetic disorder that typically occurs in individuals who inherit two copies (one from the mother and one from the father) of the C282Y mutation in the gene called HFE ("H" stands for hereditary or "high"; "Fe" is the chemical symbol for iron). However, not everyone who inherits mutations in HFE will develop hemochromatosis. The reasons that some people develop iron overload and others do not are still being studied.
If hemochromatosis is suspected, your doctor may order blood tests for iron, transferrin saturation, and ferritin. Ferritin levels greater than 300 ng/mL in men and 200 ng/mL in women support a diagnosis of hemochromatosis. However, ferritin levels can also be increased by many common disorders other than hemochromatosis.
Source: https://www.uptodate.com/contents/hereditary-hemochromatosis-beyond-the-basics