Much less widely known than the dangerous consequences of iron deficiencies is the fact that too much iron can also cause problems. The exact origin of the genetic iron overload disorder hereditary hemochromatosis (HH) has remained elusive. In a joint effort, researchers from the European Molecular Biology Laboratory (EMBL) and the University of Heidelberg, Germany, have now discovered that HH is a liver disease. They report in the current issue of Cell Metabolism that the disorder develops when a crucial gene is lacking in liver cells.