Haemochromatosis revisited.

Haemochromatosis is a genetic disease caused by hepcidin deficiency, responsible for an increase in intestinal iron absorption. Haemochromatosis is associated with homozygosity for the HFE p.Cys282Tyr mutation. However, rare cases of haemochromatosis (non-HFE haemochromatosis) can also be caused by pathogenic variants in other genes (such as HJV, HAMP, TFR2 and SLC40A1). A working group of the International Society for the Study of Iron in Biology and Medicine (BIOIRON Society) has concluded that the classification based in different molecular subtypes is difficult to be adopted in clinical practice and has proposed a new classification approaching clinical questions and molecular complexity. The aim of the present review is to provide an update on classification, pathophysiology and therapeutic recommendations.

Quality of Life Scores Remained Different among the Genotypic Groups of Patients with Suspected Hemochromatosis, Even after Treatment Period.

BACKGROUND: Hemochromatosis is a genetic condition of iron overload caused by deficiency of hepcidin. In a previous stage of this study, patients with suspected hemochromatosis had their quality of life (QL) measured. We observed that QL scores differed among genotypic groups of patients. In this reported final phase of the study, the aims were to compare QL scores after a treatment period of approximately 3 years and to analyze a possible association of the serum ferritin values with QL scores. METHODS: Sixty-five patients were enrolled in this final phase and divided into group 1 (patients that showed primary iron overload and homozygous genotype for the HFE p.Cys282Tyr mutation) and group 2 (other kinds of genotypes). Short Form 36 (SF-36) was performed and consisted of eight domains with a physical and also a mental component. RESULTS: Both groups had a significant decrease in serum ferritin concentrations: group 1 had a variation from 1844 ± 1313 ng/mL to 281 ± 294 ng/mL, and group 2 had a variation from 1216 ± 631 ng/mL to 236 ± 174 ng/mL. Group 1 had a smaller mean value for these six SF-36 domains compared with group 2, indicating a worse QL. CONCLUSIONS: In this final stage, six domains demonstrated a difference among genotypic groups (role emotional and mental health, adding to the four of the initial phase), reassuring the impact of the identified genotype on the QL of hemochromatosis patients. Furthermore, despite that both patient groups demonstrated similar and significant decreases in serum ferritin values, no association was found between the decrease in this biological parameter and the SF-36 domains.

Hemochromatosis classification: update and recommendations by the BIOIRON Society.

Hemochromatosis (HC) is a genetically heterogeneous disorder in which uncontrolled intestinal iron absorption may lead to progressive iron overload (IO) responsible for disabling and life-threatening complications such as arthritis, diabetes, heart failure, hepatic cirrhosis, and hepatocellular carcinoma. The recent advances in the knowledge of pathophysiology and molecular basis of iron metabolism have highlighted that HC is caused by mutations in at least 5 genes, resulting in insufficient hepcidin production or, rarely, resistance to hepcidin action. This has led to an HC classification based on different molecular subtypes, mainly reflecting successive gene discovery. This scheme was difficult to adopt in clinical practice and therefore needs revision. Here we present recommendations for unambiguous HC classification developed by a working group of the International Society for the Study of Iron in Biology and Medicine (BIOIRON Society), including both clinicians and basic scientists during a meeting in Heidelberg, Germany. We propose to deemphasize the use of the molecular subtype criteria in favor of a classification addressing both clinical issues and molecular complexity. Ferroportin disease (former type 4a) has been excluded because of its distinct phenotype. The novel classification aims to be of practical help whenever a detailed molecular characterization of HC is not readily available.

Iron and platelets: A subtle, under-recognized relationship.

The role of iron in the formation and functioning of erythrocytes, and to a lesser degree of white blood cells, is well established, but the relationship between iron and platelets is less documented. Physiologically, iron plays an important role in hematopoiesis, including thrombopoiesis; iron levels direct, together with genetic factors, the lineage commitment of megakaryocytic/erythroid progenitors toward either megakaryocyte or erythroid progenitors. Megakaryocytic iron contributes to cellular machinery, especially energy production in platelet mitochondria. Thrombocytosis, possibly favoring vascular thrombosis, is a classical feature observed with abnormally low total body iron stores (mainly due to blood losses or decreased duodenal iron intake), but thrombocytopenia can also occur in severe iron deficiency anemia. Iron sequestration, as seen in inflammatory conditions, can be associated with early thrombocytopenia due to platelet consumption and followed by reactive replenishment of the platelet pool with possibility of thrombocytosis. Iron overload of genetic origin (hemochromatosis), despite expected mitochondrial damage related to ferroptosis, has not been reported to cause thrombocytopenia (except in case of high degree of hepatic fibrosis), and iron-related alteration of platelet function is still a matter of debate. In acquired iron overload (of transfusional and/or dyserythropoiesis origin), quantitative or qualitative platelet changes are difficult to attribute to iron alone due to the interference of the underlying hematological conditions; likewise, hematological improvement, including increased blood platelet counts, observed under iron oral chelation is likely to reflect mechanisms other than the sole beneficial impact of iron depletion.

Novel mutations in the bone morphogenetic protein 6 gene in patients with iron overload and non-homozygous genotype for the HFE p.Cys282Tyr mutation.

BACKGROUND: Five main genes are associated with hemochromatosis; however, current studies show that, in addition to these genes, others may be associated with primary iron overload (IO). One of these is the bone morphogenetic protein 6 (BMP6), which encodes a protein that modulates hepcidin synthesis and, consequently, iron homeostasis. AIM: To identify BMP6 gene pathogenic variants in patients with IO and non-homozygous genotype for the HFE p.Cys282Tyr mutation. MATERIALS AND METHODS: Fifty-three patients with primary IO and non-homozygous genotype for the HFE p.Cys282Tyr were selected. Subsequent bidirectional DNA sequencing of BMP6 exons was performed. RESULTS: Two novel variants were found. One at homozygous state p.Gln158Ter (c.472C>T) was pathogenic, the other one at heterozygous state p.Val394Met (c.1180G>A) was of uncertain significance (VUS); the third variant at heterozygous state p.Arg257His (c.770G>A) has already been described and associated with IO. No BMP6 pathogenic variants that would explain iron overload phenotypes were detected in 94% of the studied patients. CONCLUSION: Identification of the BMP6 pathogenic variants in Brazilian patients with primary IO might contribute to the genetic understanding of this phenotype.

HFE-Related Hemochromatosis in a Chinese Patient: The First Reported Case.

HFE-related Hemochromatosis is the most common genetic iron overload disease in European populations, particularly of Nordic or Celtic ancestry. It is reported that the HFE p.C282Y mutation is present in 1/10 people of northern European descent, resulting in one in two hundred people will be homozygous. However, the HFE p.C282Y heterozygosity is virtually absent among East Asians, including Japanese, Koreans, and Chinese. In this article, we report a case of HFE-related hemochromatosis caused by compound heterozygosity HFE p.C282Y/p.R71X. This is the first report of hemochromatosis associated with HFE p.C282Y mutation in China.

What's Important and New in Hemochromatosis?

Major advances in the understanding of genetic iron overload have led to a clarification of the nosology and terminology of the related diseases. The term hemochromatosis should be reserved to the entities where iron overload is related to hepcidin deficiency or hepcidin resistance. The diagnosis of hemochromatosis is non-invasive, based on clinical examination, blood investigations and, whenever possible, magnetic resonance imaging. Phlebotomies remain the mainstay of the treatment, but new therapeutic approaches should, in the future, constitute a valuable advance, hopefully both as an adjunct to bleeding in the induction phase and as its replacement in the maintenance phase. The goal of the present review is to update the terminology of hemochromatosis in light of major pathophysiological advances, and the main features of its diagnostic and therapeutic approaches.

Too much iron: A masked foe for leukemias.

The role of iron in non-erythroid hematopoietic lineages and its implication in hemato-oncogenesis are still debated. Iron exerts an important role on hematopoietic stem cell transformation and on mature white blood cell differentiation. Iron acts experimentally as an oncogenic cofactor but its exact role in the transformation of the myelodysplastic syndrome into leukemia continues to be discussed. Body iron overload frequently develops mainly as the result of multiple erythrocyte transfusions in patients with leukemia or myelodysplastic syndrome, and, in the latter, as a result of increased ineffective erythropoiesis. Iron overload, especially through the deleterious effects of reactive oxygen species, leads to organ damage that likely impacts the global outcome of patients, especially after hematopoietic stem cell transplantation (HSCT). In these pathological settings (before and after HSCT), oral iron chelation should be considered whenever body iron overload has been firmly established, ideally by magnetic resonance imaging.

Ceruloplasmin deficiency does not induce macrophagic iron overload: lessons from a new rat model of hereditary aceruloplasminemia.

Hereditary aceruloplasminemia (HA), related to mutations in the ceruloplasmin (Cp) gene, leads to iron accumulation. Ceruloplasmin ferroxidase activity being considered essential for macrophage iron release, macrophage iron overload is expected, but it is not found in hepatic and splenic macrophages in humans. Our objective was to get a better understanding of the mechanisms leading to iron excess in HA. A clustered regularly interspaced short palindromic repeats (CRISPR)/ CRISPR associated protein 9 (Cas9) knockout of the Cp gene was performed on Sprague-Dawley rats. We evaluated the iron status in plasma, the expression of iron metabolism genes, and the status of other metals whose interactions with iron are increasingly recognized. In Cp-/- rats, plasma ceruloplasmin and ferroxidase activity were absent, together with decreased iron concentration and transferrin saturation. Similarly as in humans, the hepatocytes were iron overloaded conversely to hepatic and splenic macrophages. Despite a relative hepcidin deficiency in Cp-/- rats and the loss of ferroxidase activity, potentially expected to limit the interaction of iron with transferrin, no increase of plasma non-transferrin-bound iron level was found. Copper was decreased in the spleen, whereas manganese was increased in the plasma. These data suggest that the reported role of ceruloplasmin cannot fully explain the iron hepatosplenic phenotype in HA, encouraging the search for additional mechanisms.-Kenawi, M., Rouger, E., Island, M.-L., Leroyer, P., Robin, F., Remy, S., Tesson, L., Anegon, I., Nay, K., Derbré, F., Brissot, P., Ropert, M., Cavey, T., Loréal, O. Ceruloplasmin deficiency does not induce macrophagic iron overload: lessons from a new rat model of hereditary aceruloplasminemia.

Spleen iron, molybdenum, and manganese concentrations are coregulated in hepcidin-deficient and secondary iron overload models in mice.

Iron excess increases the hepatic expression of hepcidin, the systemic iron metabolism regulator that favors iron sequestration in the spleen. Genetic iron overload related to hepcidin insufficiency decreases the spleen iron concentration and increases hepatic iron concentration, whereas during secondary iron overload, the hepcidin expression increases together with spleen iron concentration in addition to hepatic iron concentrations increase. Links between iron metabolism and other metals being suggested, our aim was to investigate, during iron overload, the relationships between the hepatic hepcidin expression level and the hepatic and splenic concentrations of iron, manganese, copper, zinc, and molybdenum, determined using inductively coupled plasma mass spectrometry. Hepcidin-deficient mice, secondary iron overload mice models, and their respective controls were studied. Spleen molybdenum and manganese concentrations paralleled the modulation of both spleen iron concentrations, increasing in secondary iron overload and decreasing in hepcidin deficiency related iron overload, as well as hepatic hepcidin mRNA expression. Our data suggest that iron, manganese, and molybdenum metabolisms could share mechanisms controlling their distribution that are associated to hepcidin modulation. In diseases with abnormal hepcidin levels, including chronic inflammation, special attention should be paid to those metals that can participate with the phenotype.-Cavey, T., Latour, C., Island, M.-L., Leroyer, P., Guggenbuhl, P., Coppin, H., Roth, M.-P., Bendavid, C., Brissot, P., Ropert, M., Loréal, O. Spleen iron, molybdenum, and manganese concentrations are coregulated in hepcidin-deficient and secondary iron overload models in mice.

Pathophysiology and classification of iron overload diseases; update 2018.

Iron overload pathophysiology has benefited from significant advances in the knowledge of iron metabolism and in molecular genetics. As a consequence, iron overload nosology has been revisited. The hematologist may be confronted to a number of iron overload syndromes, from genetic or acquired origin. Hemochromatoses, mostly but not exclusively related to the HFE gene, correspond to systemic iron overload of genetic origin in which iron excess is the consequence of hepcidin deficiency, hepcidin being the hormone regulating negatively plasma iron. Iron excess develops following hypersideremia and the formation of non-transferrin-bound iron, which targets preferentially parenchymal cells (hepatocytes). The ferroportin disease has a totally different iron overload mechanism consisting of defective egress of cellular iron into the plasma, iron deposition taking place mostly within the macrophages (spleen). Hereditary aceruloplasminemia is peculiar since systemic iron overload involves the brain. Two main types of acquired iron overload can be seen by the hematologist, one related to dyserythropoiesis (involving hypohepcidinemia ), the other related to multiple transfusions (thalassemias, myelodysplasia, hematopoietic stem cell transplantation). Congenital sideroblastic anemias, either monosyndromic (anemia) or polysyndromic (anemia plus extra-hematological syndromes), develop both compartimental iron excess within the erythroblast mitochondria, and systemic iron overload (through dyserythropoiesis and/or transfusions).

Iron as a Therapeutic Target in HFE-Related Hemochromatosis: Usual and Novel Aspects.

Genetic hemochromatosis is an iron overload disease that is mainly related to the C282Y mutation in the HFE gene. This gene controls the expression of hepcidin, a peptide secreted in plasma by the liver and regulates systemic iron distribution. Homozygous C282Y mutation induces hepcidin deficiency, leading to increased circulating transferrin saturation, and ultimately, iron accumulation in organs such as the liver, pancreas, heart, and bone. Iron in excess may induce or favor the development of complications such as cirrhosis, liver cancer, diabetes, heart failure, hypogonadism, but also complaints such as asthenia and disabling arthritis. Iron depletive treatment mainly consists of venesections that permit the removal of iron contained in red blood cells and the subsequent mobilization of stored iron in order to synthesize hemoglobin for new erythrocytes. It is highly efficient in removing excess iron and preventing most of the complications associated with excess iron in the body. However, this treatment does not target the biological mechanisms involved in the iron metabolism disturbance. New treatments based on the increase of hepcidin levels, by using hepcidin mimetics or inducers, or inhibitors of the iron export activity of ferroportin protein that is the target of hepcidin, if devoid of significant secondary effects, should be useful to better control iron parameters and symptoms, such as arthritis.

Rare anemias due to genetic iron metabolism defects.

Anemia is defined by a deficiency of hemoglobin, an iron-rich protein that binds oxygen in the blood. It can be due to multiple causes, either acquired or genetic. Alterations of genes involved in iron metabolism may be responsible, usually at a young age, for rare forms of chronic and often severe congenital anemia. These diseases encompass a variety of sideroblastic anemias, characterized by the presence of ring sideroblasts in the bone marrow. Clinical expression of congenital sideroblastic anemia is either monosyndromic (restricted to hematological lineages) or polysyndromic (with systemic expression), depending on whether iron metabolism, and especially heme synthesis, is directly or indirectly affected. Beside sideroblastic anemias, a number of other anemias can develop due to mutations of key proteins acting either on cellular iron transport (such as the DMT1 transporter), plasma iron transport (transferrin), and iron recycling (ceruloplasmin). Contrasting with the aforementioned entities which involve compartmental, and sometimes, systemic iron excess, the iron refractory iron deficiency anemia (IRIDA) corresponds to a usually severe anemia with whole body iron deficiency related to chronic increase of plasma hepcidin, the systemic negative regulator of plasma iron. Once clinically suggested, these diseases are confirmed by genetic testing in specialized laboratories.

Haemochromatosis.

Haemochromatosis is defined as systemic iron overload of genetic origin, caused by a reduction in the concentration of the iron regulatory hormone hepcidin, or a reduction in hepcidin-ferroportin binding. Hepcidin regulates the activity of ferroportin, which is the only identified cellular iron exporter. The most common form of haemochromatosis is due to homozygous mutations (specifically, the C282Y mutation) in HFE, which encodes hereditary haemochromatosis protein. Non-HFE forms of haemochromatosis due to mutations in HAMP, HJV or TFR2 are much rarer. Mutations in SLC40A1 (also known as FPN1; encoding ferroportin) that prevent hepcidin-ferroportin binding also cause haemochromatosis. Cellular iron excess in HFE and non-HFE forms of haemochromatosis is caused by increased concentrations of plasma iron, which can lead to the accumulation of iron in parenchymal cells, particularly hepatocytes, pancreatic cells and cardiomyocytes. Diagnosis is noninvasive and includes clinical examination, assessment of plasma iron parameters, imaging and genetic testing. The mainstay therapy is phlebotomy, although iron chelation can be used in some patients. Hepcidin supplementation might be an innovative future approach.

Therapeutic recommendations in HFE hemochromatosis for p.Cys282Tyr (C282Y/C282Y) homozygous genotype.

Although guidelines are available for hereditary hemochromatosis, a high percentage of the recommendations within them are not shared between the different guidelines. Our main aim is to provide an objective, simple, brief, and practical set of recommendations about therapeutic aspects of HFE hemochromatosis for p.Cys282Tyr (C282Y/C282Y) homozygous genotype, based on the published scientific studies and guidelines, in a form that is reasonably comprehensible to patients and people without medical training. This final version was approved at the Hemochromatosis International meeting on 12th May 2017 in Los Angeles.

Quality of life scores differs between genotypic groups of patients with suspected hereditary hemochromatosis.

BACKGROUND: Hereditary hemochromatosis (HH) encompasses a group of autosomal recessive disorders mainly characterized by enhanced intestinal absorption of iron and its accumulation in parenchymal organs. HH diagnosis is based on iron biochemical and magnetic resonance imaging (MRI) assessment, and genetic testing. Questionnaires, such as SF-36 (short form health survey), have been increasingly used to assess the impact of diseases on the patient's quality of life (QL). In addition, different genotypes are identified as results of genetic tests in patients with suspected primary iron overload. In the present study, our aim was to evaluate whether domains of QL are different according to genotypic groups in patients suspected of HH. METHODS: Seventy-nine patients with primary iron overload were included and two genotypic groups were formed (group 1: homozygous genotype for the HFE p.Cys282Tyr mutation; group 2: other genotypes). RESULTS: Group 1 had higher means of plasma transferrin saturation (86 ± 19%) and serum ferritin (1669 ± 1209 ng/mL) compared to group 2 (71 ± 12%, 1252 ± 750 ng/mL, respectively; p = 0.001). Four domains were significantly different among groups 1 and 2: physical functioning (p = 0.03), bodily pain (p = 0.03), vitality (p = 0.02) and social functioning (p = 0.01). CONCLUSIONS: Our main finding was that patients with p.Cys282Tyr homozygosity had a worse QL scenario assessed by SF-36, compared with patients with iron overload without the same genotype. Being aware of this relationship between genotypes and QL might be helpful in the overall management of patients suspected of hereditary hemochromatosis.

Hemochromatosis: a model of metal-related human toxicosis.

Many environmental agents, such as excessive alcohol intake, xenobiotics, and virus, are able to damage the human body, targeting especially the liver. Metal excess may also assault the liver. Thus, chronic iron overload may cause, especially when associated with cofactors, diffuse organ damage that is a source of significant morbidity and mortality. Iron excess can be either of acquired (mostly transfusional) or of genetic origin. Hemochromatosis is the archetype of genetic iron overload diseases and represents a serious health problem. A better understanding of iron metabolism has deeply modified the hemochromatosis field which today benefits from much more efficient diagnostic and therapeutic approaches.

Genetic hemochromatosis: Pathophysiology, diagnostic and therapeutic management.

The term hemochromatosis (HC) corresponds to several diseases characterized by systemic iron overload of genetic origin and affecting both the quality of life and life expectancy. Major improvement in the knowledge of iron metabolism permits to divide these diseases into two main pathophysiological categories. For most HC forms (types 1, 2, 3 and 4B HC) iron overload is related to cellular hepcidin deprivation which causes an increase of plasma iron concentration and the appearance of plasma non-transferrin bound iron. In contrast, iron excess in type 4A ferroportin disease is related to decreased cellular iron export. Whatever the HC type, the diagnosis rests on a non-invasive strategy, combining clinical, biological and imaging data. The mainstay of the treatment remains venesection therapy with the perspective of hepcidin supplementation for hepcidin deprivation-related HC. Prevention of HC is critical at the family level and, for type 1 HC, remains a major goal, although still debated, at the population level.

The interaction of iron and the genome: For better and for worse.

Iron, as an essential nutrient, and the DNA, as the carrier of genetic information which is physically compacted into chromosomes, are both needed for normal life and well-being. Therefore, it is not surprising that close interactions exist between iron and the genome. On the one hand, iron, especially when present in excess, may alter genome stability through oxidative stress, and may favor cell cycle abnormalities and the development of malignant diseases. The genome also receives a feedback signal from the systemic iron status, leading to promotion of expression of genes that regulate iron metabolism. Conversely, on the other hand, DNA mutations may cause genetic iron-related diseases such as hemochromatosis, archetype of iron-overload diseases, or refractory iron deficiency anemia (IRIDA).