Genetic iron overload has long been confined to the picture of classical hemochromatosis related to the HFE C282Y mutation (type 1 hemochromatosis). C282Y homozygosity affects approximately three people out of 1000 of the Caucasian population, representing one of the most frequent genetic predispositions. It has, however, rapidly become clear that the HFE C282Y mutation is not the sole culprit in genetic iron overload. Several novel mutations in HFE and other genes have been discovered and related to various entities, which are now known as types 2, 3 and 4 hemochromatosis. These diseases are far less frequent than the classical type 1 hemochromatosis but, by contrast, are not limited to the Caucasian population. Molecular diagnosis obviously plays a key role in the diagnostic strategy. In the future, it will undoubtedly enable not only identification of new diagnostic markers, but also provide potential molecular targets for pathophysiologically based innovative therapeutic approaches.