Control of iron metabolism – Lessons from neonatal hemochromatosis

Abstract

When hepatologists begin their investigations at the scene of liver damage, iron is certainly on the list of ‘‘usual suspects’’ to be rounded up. Hemochromatosis, a well-known cause of chronic liver disease, is the most prevalent genetic disorder in adults [1]. Serum iron parameters are therefore included in most guidelines on how to investigate patients with elevated transaminases or chronic liver disease [2]. The hemochromatosis (HFE) genotype is an important piece of evidence in patients with liver disease and elevated transferrin saturation with hyperferritinemia, because homozygosity for the C282Y allele of HFE is considered sufficient to diagnose hemochromatosis under these circumstances [1]. Compound heterozygosity for C282Y and H63D has been almost removed from the watch-list and is currently considered a mere risk factor for liver diseases – sufficient to cause hemochromatosis or even cirrhosis only in combination with other health burdens. Hence, a partner in crime for HFE mutation must be found in patients with liver disease and C282Y/H63D compound heterozygosity [3]. If there is evidence for iron overload in the absence of hemochromatosis-associated HFE genotypes and the hepatopathologist finds iron confined to hepatocytes, sharp investigators are well advised to search for the culprit in the genes encoding transferrin receptor 2 (TFR2) and ferroportin (SLC40A1) or even to hunt for combined mutations in these genes if a patient presents with severe iron overload or early-onset disease [4]. If the patient is adolescent or before the 3rd decade of life and presents with heart failure or hypogonadism in addition to – often overlooked – liver disease, other genes will be committed in custody. Mutations in HJV and HAMP, which respectively encode hemojuvelin and hepcidin, will be sufficient to identify juvenile hemochromatosis [5]. Through the power of genetics, iron-related diseases are now subject to close scrutiny. In addition, genetic studies have greatly advanced our understanding of hemochromatosis. This progress is reflected in the proposed re-classification of human iron