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Alanine aminotransferase (ALT)ALT is found in blood serum and in certain body tissues, especially hepatic tissues. It is released into the bloodstream by injury or disease affecting the liver (see SGPT).
AllelesAlternate forms or varieties of a gene. Alleles for a trait occupy the same locus or position on homologous chromosomes and thus govern the same trait.
AmenorrheaAbsence or abnormal stoppage of menstruation; also called amenia.
AnemiaIron deficiency leading to decreased red blood cell levels and insufficient amounts of hemoglobin and myoglobin, resulting in weakness, fatigue, susceptibility to infection, and paleness.
ArrhythmiaAny variation from the normal heart beat rhythm, including sinus premature beat, heart block, atrial fibrillation, atrial flutter, and paroxysmal tachycardia.
ArthralgiaJoint pain.
ArthropathyAny joint disease.
Aspartate aminotransferase (AST)A hepatic enzyme released into the blood when certain organs or tissues, particularly the liver and heart, are injured. AST is also known as serum glutamic oxaloacetic transaminase (SGOT).
AutosomeAny chromosome other than a sex chromosome. Humans have 22 pairs of autosomal chromosomes; and the HFE gene is on autosomal chromosome 6.
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C282Y mutationA missense mutation that causes the amino acid tyrosine to replace a cysteine at position 282 in the HFE protein, which normally helps regulate iron uptake. This causes the HFE protein to misfold and malfunction, which can lead to increased iron absorption. About 5 of every 1,000 Americans of European dissent are homozygotes for this mutation.
CardiomyopathyGeneral diagnostic term designating primary myocardial disease that may lead to chronic heart disease.
CarrierAn individual who has one copy of a mutant allele that causes disease only when two copies are present. Although the associated disease does not affect carriers, two carriers can produce a child who has the disease.
Chelation therapyThe use of a ring-shaped compound, or iron-chelating agent, capable of forming complexes with circulating iron and assisting in its removal from the body (see deferoxamine).
ChromosomeA threadlike package of genes and other DNA in the cell nucleus. Humans have 23 pairs of chromosomes; 44 autosomes, and 2 sex chromosomes. Children get half their chromosomes from the mother and half from the father.
CirrhosisCirrhosis is a disease characterized by scarring of the liver, causing fibrosis and nodular regeneration. Destruction of normal liver architecture prevents the liver from properly digesting food, metabolizing drugs, or making proteins. Cirrhosis is a serious condition.
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Deferoxamine (desferal Rx)Iron-chelating agent used therapeutically to treat acute iron intoxication or chronic iron overload in transfusion-dependent patients. May also be used to treat hemochromatosis in patients such as anemics who cannot tolerate phlebotomy. It forms a water-soluble complex with iron that is excreted in urine and feces (see chelation therapy).
Diabetes mellitus type IThe islets of Langerhans are destroyed as a consequence of genetic susceptibility, followed by the onset of autoimmune destruction triggered by an environmental factor such as a viral infection. The number and size of insulin-producing cells in the pancreas are eventually reduced, leading to decreased insulin production and glucose intolerance.
Diabetes mellitus type IIA chronic disease that results when the body's insulin does not effectively move glucose from the blood to the interior of cells. Excess glucose builds up in the blood and is removed by the kidneys, resulting in excessive thirst, frequent urination, hunger, fatigue, weight loss, and increased insulin production.
Diagnostic testBlood testing used when a specific disease is suspected, to verify the disease’s presence and severity (see TS and SF).
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ErythropoiesisThe production of erythrocytes, or red blood cells.
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Fasting blood drawFor a fasting blood draw, avoid the following items 24 hours prior to blood draw: vitamin C, nutritional supplements, medicinal iron or estrogen preparations, iron-containing placebos of some oral contraceptives, and alcohol.
FerritinIron-storage protein (see serum ferritin).
Free radicalsHighly reactive molecules with unsatisfied electron valence pairs, capable of causing tissue damage and enhancing the effects of aging. Elevated iron levels are thought to increase the occurrence of free radical formation in the body.
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Genetic screeningTesting of a population group to identify a subset of individuals who carry a genetic mutation (H63D, C282Y) and are consequently at higher risk for having or transmitting a specific genetic disorder. Patients should receive counseling before undergoing genetic screening.
GenotypeThe genetic identity of an individual that does not contribute to outward characteristics. Genetic makeup.
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H63D mutationA missense mutation that causes the amino acid aspartate to replace a histidine at position 63 in the HFE protein, which can lead to primary iron overload. H63D has an allele frequency of approximately 16% in the U.S. general population.
HematocritThe percentage of packed red blood cells found in a unit volume of blood. Normal levels are 35%-45% for females and 40%-50% for males.
Heme ironThe iron found in the hemoglobin and myoglobin of foods such as meat, poultry, and fish. It is 2-3 times more absorbable than nonheme iron.
HemochromatosisThe disease that occurs as a result of significant iron overload. Hemochromatosis can have genetic and nongenetic causes.
HemoglobinThe protein that gives red blood cells their color; about 75% of the body’s iron is bound to hemoglobin and involved in oxygen transport from the lungs to the rest of the body. Regular levels are approximately 16 g/dL for men and 14 g/dL for women.
Hemolytic anemiaAnemia caused by the destruction of red blood cells by a disease process. Occurs in newborns as a result of blood- group incompatibility between mother and baby. It is also caused by abnormal red cell membranes or abnormal hemoglobin, i.e., sickle cell anemia and thallassemia. Complications include all the ill effects of profound anemia as well as possible problems caused by jaundice.
HemosiderinAn iron-containing pigment formed when the potential to store iron as ferritin is exceeded; a type of storage iron.
HemosiderosisExcessive iron accumulation due to transfusion, medication, dietary overload, and other reasons. May produce the same pathologic changes as hereditary hemochromatosis.
Hepatic biopsyRemoval of a small piece of liver tissue for microscopic examination or testing. A liver biopsy can be used to confirm the hemochromatosis diagnosis by assessing the amount of iron per gram in liver tissue.
Hepatic enzymesVarious enzymes (ALT, SGPT, AST, SGOT, and GGT) that leak into the bloodstream as a result of injury to liver cells from infection, iron overload, or bile flow obstruction. Elevated enzymes are suggestive of liver damage.
Hepatic iron concentrationThe amount of iron in the liver. Measured by atomic absorption spectrophotometry of hepatic parenchymal cells or histologically with Perl’s stain. Normal values are <80 mol/g dry weight; >80 mol/g indicates overload.
HepatitisInflammation of the liver.
Hepatocellular carcinomaA malignant growth made up of liver epithelial cells that tend to infiltrate the surrounding tissues and give rise to metastases. Liver cancer.
HepatomegalyEnlargement of the liver.
Hereditary hemochromatosisThe genetic disease that results from significant iron overload.
The majority of hereditary hemochromatosis (also known as Type I Hemochromatosis) is associated with homozygous mutations in the HFE gene. There are other heritable forms, presumably associated with other genes.
HeterozygousPossessing two different forms (alleles) of a particular gene, one inherited from each parent, e.g. C2824/H63D.
HFE geneThe gene-encoding translation of the HFE protein, which plays a roll in iron absorption. Mutations of this gene can predispose to developing primary iron overload. An estimated 10% of the U.S. population carries an HFE gene mutation.
HFE gene mutationsThe HFE gene protein product is a transmembrane glycoprotein that modulates iron uptake. Mutations in this gene compromise its function and can lead to iron overloading.
HFE proteinAn HLA-like protein that is expressed on the surface of duodenal crypt enterocytes and participates in iron uptake and transport. Mutations in this gene appear to cause these cells to lose the ability to sense the level of body iron stores.
HomozygousPossessing two identical forms (alleles) of a particular gene, one inherited from each parent. Individuals who are homozygous for a trait are referred to as homozygotes, e.g. C2824/C2824.
HyperferremiaHigh levels of serum iron caused by random iron overload (repeated transfusions, primary hemochromatosis), liver disease, disordered or decreased erythropoiesis, or hemolytic anemia.
HyperthyroidismOveractive thyroid.
HypotensionAbnormally low blood pressure.
HypothyroidismUnderactive thyroid.
HypovolemiaAbnormally decreased volume of blood circulating in the body.
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Iron overloadThe accumulation of excess iron in body tissues.

Iron overload usually occurs as a result of a genetic predisposition to absorb iron in excess of normal.

Iron overload can also occur as a complication of:

  • Other hematologic disorders, e.g., inherited and acquired anemias.
  • Chronic transfusion therapy or repeated injections of iron dextram.
  • Chronic hepatitis.
  • Excessive iron ingestion.
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Juvenile hemochromatosisNon-HFE hemochromatosis in a person younger than age 30. Also known as Hemochromatosis Type 2A or 2B (see Heritable and Acquired Disorders Associated with Iron Overload.)
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Missense mutationA nucleotide substitution within a gene that changes a codon so that it codes for a different amino acid in the protein. This usually changes the activity of the protein.
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NeoplasmAny new and abnormal tissue growth.
Non-alcoholic steatohepatitis (NASH)A liver that contains fatty deposits and shows evidence of inflammation but has not been damaged by alcohol.
Nonheme ironThe iron in plant-based and iron-fortified foods.
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PenetranceThe proportion of individuals with a specific genotype who manifest the genotype at the phenotype level. In other words, those carrying a gene that also outwardly express traits for that gene.
PhenotypeManifestation of a genetic trait as a clinically observable sign or symptom.
PhlebotomyTo puncture a vein for the purpose of withdrawing blood. The preferred treatment for those suffering from hemochromatosis.
Porphyria cutanea tardaDisorder of heme biosynthesis due to a defective liver enzyme (uroporphyrinogen decarboxylase). Symptoms include photosensitivity; hepatic dysfunction; discolored teeth, gums and skin; excessive hair; and psychiatric symptoms that result from porphyrin accumulation in the blood.
PrevalenceThe percentage of cases of a disease in a population at a given time.
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Recessive traitA genetic disorder that appears only in patients who have two copies of a mutant allele, one from each parent. An individual who has one copy of the mutant allele is a carrier.
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S65C mutationA missense mutation that causes a cysteine to replace a serine at nucleotide position 193. The mutation is in a region implicated in binding the transferrin receptor to the HFE protein, and has a modest effect on iron metabolism. S65C has an allele frequency of 1.5% in the general population.
Secondary hemochromatosisAcquired forms of hemochromatosis. Caused by various anemias, chronic transfusion therapy, or other nongenetic conditions.
SerumBlood serum is the noncellular clear liquid that separates from blood on clotting. Serum is equivalent to plasma without plasma’s clotting elements.
Serum ferritin test (SF)Determines serum ferritin levels. The body increases production of serum ferritin when excess iron is absorbed. Normal levels are <200 ng/ml for premenopausal females, <300 for males and postmenopausal females.
Serum glutamic- oxaloacetic transaminase (SGOT)A hepatic enzyme detected in blood tests and used in cases of suspected coronary occlusive heart disease, or liver diseases such as hepatitis or cirrhosis. A 2 to 3-fold increase in SGOT is found in 50-60% of patients with HHC (see AST).
Serum glutamic pyruvic transaminase (SGPT)An enzyme released into the bloodstream due to injury or disease affecting the liver: it is found mainly in blood serum and hepatic tissues. SGPT levels are checked for suspected liver disease and mononucleosis, or to monitor the effect of long-term drug therapy on the liver (see ALT).
Sideroblastic anemiaTerm used to describe a group of rare blood disorders characterized by the bone marrow's inability to manufacture normal red blood cells.
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TachycardiaExcessive rapidity in the action of the heart; the term is usually applied to a heart rate above 100 beats per minute.
ThalassemiaAn inherited hemoglobin synthesis disorder resulting in reduced globin chain synthesis and chronic hemolytic anemia. Treating anemia by chronic transfusion therapy predisposes to secondary hemochromatosis.
Therapeutic phlebotomyA procedure in which a unit of blood is collected via venipuncture to treat a condition such as iron overload.
Total iron binding capacity (TIBC)Measurement of the maximum iron concentration that transferrin can bind. Increased TIBC levels may indicate iron-deficiency anemia; decreased TIBC may indicate cirrhosis (TIBC = UIBC + serum iron).
TransaminaseOne of the aminotransferase enzymes, which catalyze the transfer of an amino group from an alpha-amino acid to an alpha-keto acid.
TransferrinA protein synthesized in the liver that transports iron in the blood to red blood cells for use in heme synthesis.
Transferrin receptor, TfRA transmembrane disulfide-linked dimer of identical 85-kDa polypeptides mediating iron uptake. The amount of transferrin receptor expressed on a cell is proportional to the cell's need for iron. Since the majority of metabolic iron is used for hemoglobin synthesis, 80% of total TfR is on erythroid precursor cells.
Transferrin saturation test (TS)Proportion of transferrin proteins that are carrying iron. Normal range is 16%-45% in a fasting TS. Elevated TS indicates iron overloading.(serum iron [SI] / TIBC x 100) or (SI / SI + UIBC x 100).
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Unsaturated iron binding capacity (UIBC)About one third of transferrin iron-binding sites are occupied by iron; therefore, serum has considerable reserve iron-binding capacity. This is called serum unsaturated iron binding capacity (UIBC) (see TIBC).
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Vibrio vulnificusA microbe that causes food-poisoning-like symptoms.
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Wild typeIn genetics, the standard phenotype for any organism, or a gene that determines a standard phenotypic trait.
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Glossary References

Discovering Nutrition

List and Glossary of medical terms by Robert H. Vander Stichele

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