IRON OVERLOAD TURMOIL'' AND "MANAGEMENT OF HEMOCHROMATOSIS (original) (raw)

Iron-overload–related disease in HFE hereditary hemochromatosis

New England Journal of Medicine, 2008

Background Most persons who are homozygous for C282Y, the HFE allele most commonly asssociated with hereditary hemochromatosis, have elevated levels of serum ferritin and transferrin saturation. Diseases related to iron overload develop in some C282Y homozygotes, but the extent of the risk is controversial.

Hereditary Hemochromatosis: an Inherited Abnormality of Iron Regulation

International Journal of Current Science Research and Review, 2022

Hereditary Hemochromatosis (HH) is an autosomal recessive genetic disease characterized by abnormalities in iron regulation, mostly due to mutations in the HFE gene, leading to increased iron absorption due to hepcidin deficiency. The classification of HH is based on the type of mutated gene, which must be distinguished from non-genetic conditions that cause secondary elevations in serum iron levels such as multiple transfusions and increased iron supplementation. Pathophysiological mechanisms of HH include increased absorption of iron in the upper intestine, decreased expression of the iron regulatory hormone hepcidin, altered function of the HFE protein, and tissue damage and fibrogenesis caused by iron overload. The human body is physiologically unable to excrete excess iron load so excess iron in serum will be deposited in various organs, causing organ dysfunction. The clinical manifestations of hemochromatosis vary widely depending on the location of iron deposition in the organ. The classic clinical triad of hemochromatosis is liver cirrhosis, skin pigmentation, and diabetes mellitus. Hemochromatosis can be screened for and diagnosed by examining serum ferritin levels, transferrin saturation, unsaturated iron-binding capacity, total ironbinding capacity, liver biopsy, magnetic resonance imaging, and genetic testing. The main treatment for hemochromatosis at this time is phlebotomy although other therapeutic methods can also be used to help lower iron levels and improve the patient's clinical course, such as therapy with chelating agents, erythrocytopharesis, and liver transplantation. If hemochromatosis is not treated, the patient can experience progressive liver damage leading to cirrhosis and hepatocellular carcinoma, and complications due to damage to various tissues and organs.

Hereditary hemochromatosis: A prevalent disorder of iron metabolism with an elusive etiology

American Journal of Hematology, 1994

Hereditary hemochromatosis is a prevalent inherited disorder with an estimated frequency of homozygosity of 0.2 to 0.45% in Caucasians. The disease is characterized by progressive iron overload until a massive accumulation of body iron occurs. Undetected, the disorder eventually can produce either cirrhosis, diabetes mellitus, cardiac disease, arthritis, or hepatocellular carcinoma or a combination of these manifestations. Early diagnosis and treatment prevents organ damage and normalizes life expectancy. Screening studies to detect hemochromatosis are most effectively accomplished by measurement of the serum iron and total iron binding capacity. Treatment is most effectively performed by frequent phlebotomy until body stores are empty and then 3 to 4 times yearly for life. The basic defect of hemochromatosis appears to increase iron absorption, decrease iron excretion, and produce preferential deposit of iron in hepatic parenchymal cells rather than Kupffer cells. The genetic abnormality of hemochromatosis is located on chromosome 6 in close association with the gene for HLA antigens. Recent speculation postulates that tumor necrosis factor may be involved in the etiology of this disease because of its location on chromosome 6 and its effect upon iron transport.

Inherited Disorders of Iron Overload

Frontiers in Nutrition

Dietary iron absorption and systemic iron traffic are tightly controlled by hepcidin, a liver-derived peptide hormone. Hepcidin inhibits iron entry into plasma by binding to and inactivating the iron exporter ferroportin in target cells, such as duodenal enterocytes and tissue macrophages. Hepcidin is induced in response to increased body iron stores to inhibit further iron absorption and prevent iron overload. The mechanism involves the BMP/SMAD signaling pathway, which triggers transcriptional hepcidin induction. Inactivating mutations in components of this pathway cause hepcidin deficiency, which allows inappropriately increased iron absorption and efflux into the bloodstream. This leads to hereditary hemochromatosis (HH), a genetically heterogenous autosomal recessive disorder of iron metabolism characterized by gradual buildup of unshielded non-transferrin bound iron (NTBI) in plasma and excessive iron deposition in tissue parenchymal cells. The predominant HH form is linked to mutations in the HFE gene and constitutes the most frequent genetic disorder in Caucasians. Other, more severe and rare variants are caused by inactivating mutations in HJV (hemojuvelin), HAMP (hepcidin) or TFR2 (transferrin receptor 2). Mutations in SLC40A1 (ferroportin) that cause hepcidin resistance recapitulate the biochemical phenotype of HH. However, ferroportin-related hemochromatosis is transmitted in an autosomal dominant manner. Loss-of-function ferroportin mutations lead to ferroportin disease, characterized by iron overload in macrophages and low transferrin saturation. Aceruloplasminemia and atransferrinemia are further inherited disorders of iron overload caused by deficiency in ceruloplasmin or transferrin, the plasma ferroxidase and iron carrier, respectively.

HFE-associated hereditary hemochromatosis

Genetics in Medicine, 2009

In populations of northern European descent, the p.C282Y mutation in the HFE gene is highly prevalent, and HFE-associated hereditary hemochromatosis is the most common type of inherited iron overload disorder. Inappropriate low secretion of hepcidin, which negatively regulates iron absorption, is postulated to be the mechanism for iron overload in this condition. The characteristic biochemical abnormalities are elevated serum transferrin-iron saturation and serum ferritin. Typical clinical manifestations include cirrhosis, liver fibrosis, hepatocellular carcinoma, elevated serum aminotransferase levels, diabetes mellitus, restrictive cardiomyopathy and arthropathy of the second and third metacarpophalangeal joints. Most patients are now diagnosed before the development of these clinical features. Molecular genetic tests are currently available for genotypic diagnosis. In selected individuals, diagnosis might require liver biopsy or quantitative phlebotomy. Iron depletion by phlebotomy is the mainstay of treatment and is highly effective in preventing the complications of iron overload if instituted before the development of cirrhosis. Genetic testing is currently not recommended for population screening because of low yield as the majority of the healthy, asymptomatic p.C282Y homozygotes do not develop clinically significant iron overload. HFE gene testing remains an excellent tool for the screening of first-degree relatives of affected probands who are p.C282Y homozygotes.