Helicobacter pylori infection and HFE hemochromatosis

Is blood of uncomplicated hemochromatosis patients safe and effective for blood transfusion? A systematic review

Hemochromatosis is a disorder of the iron metabolism, characterized by high body iron content, necessitating frequent phlebotomies to remove excess iron. In some countries, this blood is discarded and not used for blood transfusion because of the non-voluntary character of this donation, and because a potential risk of microbial contamination of the donor blood is assumed. A systematic review was performed in order to collect and critically examine solid evidence with regard to the effectiveness and safety of blood for transfusion when derived from hemochromatosis patients who do not suffer from complications or organ damage. Using three databases (The Cochrane Library, MEDLINE, and Embase) we searched for studies from date of inception until January 2012. Out of 3470 articles, 80 references that were relevant to our question were selected, including many opinion pieces, comments, letters, and narrative reviews. Based on our selection criteria, we finally retained only six observational studies, so evidence on this subject is scarce and furthermore, the strength of the available evidence is low to very low, due to poor study designs. We found no evidence that red blood cell concentrates from hemochromatosis patients without complications of iron overload do not comply with the physiological quality requirements for transfusion, nor that their blood would present a greater risk to recipient safety than blood from non-hemochromatosis donors. However, in vitro findings from two studies suggest that iron-overloaded patients would be more susceptible to bacterial growth, but future in vivo studies are warranted to confirm this. Based on this, we call for harmonization of the blood donor selection policy among countries allowing hemochromatosis patients who do not suffer from complications of iron overload to donate blood, once iron levels are normalized.

Iron and the liver: update 2008

The cross-talk which has taken place in recent years between clinicians and scientists has resulted in a greater understanding of iron metabolism with the discovery of new iron-related genes including the hepcidin gene which plays a critical role in regulating systemic iron homeostasis. Consequently, the distinction between (a) genetic iron-overload disorders including haemochromatosis related to mutations in the HFE, hemojuvelin, transferrin receptor 2 and hepcidin genes and (b) non-haemochromatotic conditions related to mutations in the ferroportin, ceruloplasmin, transferrin and di-metal transporter 1 genes, and (c) acquired iron-overload syndromes has become easier. However, major challenges still remain which include our understanding of the regulation of hepcidin production, the identification of environmental and genetic modifiers of iron burden and organ damage in iron-overload syndromes, especially HFE haemochromatosis, indications regarding the new oral chelator, deferasirox, and the development of new therapeutic tools interacting with the regulation of iron metabolism.

Current approach to hemochromatosis

Iron overload diseases of genetic origin are an ever changing world, due to major advances in genetics and molecular biology. Five major categories are now established: HFE-related or type1 hemochromatosis, frequently found in Caucasians, and four rarer diseases which are type 2 (A and B) hemochromatosis (juvenile hemochromatosis), type 3 hemochromatosis (transferrin receptor 2 hemochromatosis), type 4 (A and B) hemochromatosis (ferroportin disease), and a(hypo)ceruloplasminemia. Increased duodenal iron absorption and enhanced macrophagic iron recycling, both due to an impairment of hepcidin synthesis, account for the development of cellular excess in types 1, 2, 3, and 4B hemochromatosis whereas decreased cellular iron egress is involved in the main form of type 4A) hemochromatosis and in aceruloplasminemia. Non-transferrin bound iron plays an important role in cellular iron excess and damage. The combination of magnetic resonance imaging (for diagnosing visceral iron overload) and of genetic testing has drastically reduced the need for liver biopsy. Phlebotomies remain an essential therapeutic tool but the improved understanding of the intimate mechanisms underlying these diseases paves the road for innovative therapeutic approaches.

Iron storage disease: facts, fiction and progress

There are many forms of iron storage disease, some hereditary and some acquired. The most common of the hereditary forms is HFE-associated hemochromatosis, and it is this disorder that is the main focus of this presentation. The body iron content is regulated by controlling absorption, and studies in the past decade have clarified, in part, how this regulation functions. A 25-amino-acid peptide hepcidin is up-regulated by iron and by inflammation, and it inhibits iron absorption and traps iron in macrophages by binding to and causing degradation of the iron transport protein ferroportin. Most forms of hemochromatosis results from dysregulation of hepcidin or defects of hepcidin or ferroportin themselves. Hereditary hemochromatosis was once considered to be very rare, but in the 1970s and 1980s, with the introduction of better diagnostic tests, it was considered the most common disease among Europeans. Controlled epidemiologic studies carried out in the last decade have shown, however, the disease itself actually is rare, and only its genotype and associated biochemical changes that are common. We do not understand why only a few homozygotes develop severe disease. It now seems unlikely that there are important modifying genes, and although alcohol is known to have some effect, excess drinking probably plays only a modest role in determining the hemochromatosis phenotype. Hereditary hemochromatosis is readily treated by phlebotomy. Secondary forms of the disease require chelation therapy, and the recent introduction of effective oral chelating agents is an important step forward in treating patients with disorders in which iron overload often proves to be fatal, such as thalassemia, myelodysplastic anemias, and dyserythropoietic anemias. While much has been learned about the regulation of iron homeostasis in the past decade, many mysteries remain and represent challenges that will keep us occupied for years to come.