Mechanisms of iron accumulation in hereditary hemochromatosis

Robert E Fleming1, William S Sly

  • 1Department of Pediatrics, Saint Louis University School of Medicine, 1402 South Grand Boulevard, St. Louis, Missouri 63104, USA. flemingr@slu.edu

Hereditary hemochromatosis (HH) is a common inborn error of iron metabolism characterized by excess dietary iron absorption and iron deposition in several tissues. Clinical consequences include hepatic failure, hepatocellular carcinoma, diabetes, cardiac failure, impotence, and arthritis. Despite the discovery of the mutation underlying most cases of HH, considerable uncertainty exists in the mechanism by which the normal gene product, HFE, regulates iron homeostasis. Knockout of the HFE gene clearly confers the HH phenotype on mice. However, studies on HFE expressed in cultured cells have not yet clarified the mechanism by which HFE mutations lead to increased dietary iron absorption. Recent discoveries suggest other genes, including a second transferrin receptor and the circulating peptide hepcidin, participate in a shared pathway with HFE in regulation of iron absorption. This review summarizes our current understanding of the relationship between iron stores and absorption and presents models to explain the dysregulated iron homeostasis in HH.

Related Concept Videos

The Early Endosome: Endocytosis of Transferrin01:28

The Early Endosome: Endocytosis of Transferrin

Essential proteins such as insulin or low-density lipoprotein (LDL) and micronutrients such as iron enter a eukaryotic cell through receptor-mediated endocytosis. Subsequently, the early endosomes fuse with the vesicles containing such receptor-ligand complexes and play a vital role in sorting the incoming ligands and receptors. While the ligands are either degraded inside the vesicle or released into the cytosol, their receptors are returned to the plasma membrane for further rounds of...
Necrosis01:16

Necrosis

Necrosis is considered as an “accidental” or unexpected form of cell death that ends in cell lysis. The first noticeable mention of “necrosis” was in 1859 when Rudolf Virchow used this term to describe advanced tissue breakdown in his compilation titled “Cell Pathology”.
Morphological Manifestations of Necrosis
Necrotic cells show different types of morphological appearance depending on the type of tissue and infection. In coagulative necrosis, cells become anucleated and die, but their...
Lifecycle of Erythrocytes01:22

Lifecycle of Erythrocytes

Erythrocytes, also known as red blood cells, constantly move through blood capillaries. As a result, they damage their plasma membrane due to the continuous friction. Typically, after 100 to 120 days, erythrocytes become rigid and fragile as they wear out. As they pass through small vessels in the spleen and liver, they can get trapped and break apart into fragments.
The resident phagocytic macrophages deal with these damaged cells by engulfing them and separating their globin and heme groups.
Microbes and Other Elemental Cycles01:24

Microbes and Other Elemental Cycles

Microbial activity plays a pivotal role in the biogeochemical cycling of iron and manganese, especially at the redox gradients characteristic of stratified aquatic environments. These cycles are driven by microbial transformations between oxidized and reduced forms of the metals, allowing organisms to exploit them for metabolic energy and structural purposes.Iron Cycling Across Redox GradientsIn neutral, oxygen-rich surface waters, iron is predominantly found in its oxidized, insoluble ferric...
Cirrhosis II: Pathophysiology01:24

Cirrhosis II: Pathophysiology

Cirrhosis is a progressive chronic liver injury caused by prolonged inflammation, excessive fibrotic remodeling, and impaired regeneration. Over time, repeated hepatic insults disrupt the liver’s architecture and function, leading to reduced blood flow, impaired bile drainage, and diminished metabolic capacity.Pathophysiology of cirrhosisCirrhosis arises from three main responses to chronic liver damage: inflammation, immune activation, and hepatocyte death. These processes lead to structural...
Jaundice01:25

Jaundice

Jaundice, or icterus, is the yellow discoloration of the skin, sclerae, and mucous membranes. It happens when plasma bilirubin levels rise above 2.5-3 mg/dL, leading to bilirubin deposition in tissue.Bilirubin is a byproduct of hemoglobin degradation. In macrophages, hemoglobin breaks down into globin and heme. Globin is converted into amino acids, while heme is turned into biliverdin by heme oxygenase, which is then reduced to unconjugated bilirubin by biliverdin reductase.Unconjugated...