A brief explanation of difficult words and terms in HAE

On this page you will find a HAE related glossary. If you don’t locate what you are looking for do not hesitate to send us a note with your topic.

Click to expand and see the explanations to terms starting with that specific letter.

Abdomen is the medical (Latin) name for the cavity between the chest and pelvis and its internal organs.

ACE inhibitor
ACE inhibitors (short for Angiotensin Converting Enzyme inhibitors) are a class of drugs used to treat high blood pressure. Amongst other mechanisms, ACE inhibitors inhibit degradation of bradykinin, leading to an increase of bradykinin levels, which can trigger angioedema. This can happen the first time an ACE inhibitor is taken. ACE inhibitors are for examples captopril, enalapril, lisinopril and ramipril.

Acquired Angioedema
Acquired angioedema (AAE) also known as acquired C1 inhibitor deficiency. Usually starts in the fourth decade of life. There are 2 forms: of acquired angioedema – type I (AAE-I) and acquired angioedema type II (AAE-II). AAE-I is associated with other diseases, most commonly B-cell lymph proliferative disorders. AAE-II is an autoimmune process defined by the presence of an autoantibody directed against the C1 inhibitor molecule (C1-INH).

Adrenaline is a hormone that is formed in the adrenal medulla and released into the blood in stressful situations. Among other things, adrenaline increases blood pressure, speeds up the heartbeat and dilates the bronchi. It is administered (in combination with other drugs) in an emergency involving anaphylactic shock. In this situation, it causes the blood vessels to constrict, increases cardiac output and makes it easier for the patient to breathe.

An agonist is a naturally occurring or synthetic substance (e.g. a drug) that binds to a cell receptor and activates it, thereby triggering certain responses in the cell. An example of an agonist is the tissue hormone bradykinin, which increases the permeability of the blood vessels by binding to its receptor. The opposite of an agonist is an antagonist.

An allergy is an overreaction of the immune system to substances in the environment that are usually harmless, such as pollen or food components, or to insect venom and drugs. The substances that trigger the allergy are called allergens. The body responds to allergens with signs of inflammation and production of antibodies. The tissue hormone histamine is the main cause of reactions such as swelling, redness and itching. In extreme cases, an allergic reaction can escalate to anaphylactic shock, which can result in cardiovascular failure. An allergic reaction can manifest itself on the skin in the form of wheals (urticaria).

Anaphylactic shock
Anaphylactic shock is the most severe form of an allergic reaction and can be triggered by allergens such as drugs, insect venom or food components. Within a few minutes of contact with the allergen, there is a rapid drop in blood pressure with reduced perfusion of important organs. In extreme cases, fatal cardiovascular failure occurs.

Androgen is the generic term for any natural or synthetic compound, usually a steroid hormone, that stimulates or controls the development and maintenance of masculine characteristics in vertebrates by binding to androgen receptors. This includes the activity of the accessory male sex organs and development of male secondary sex characteristics. Androgens, which were first discovered in 1936, are also called androgenic hormones or testoids. Androgens are also the original anabolic steroids. They are also the precursor of all estrogens, the female sex hormones. The primary and most well-known androgen is testosterone.

Angioedema is the name for an acute swelling that occurs in subcutaneous tissue or mucous membranes and can last from several hours to days. The swelling can affect both external areas (face, extremities and genitalia) and internal organs (digestive tract). Laryngeal edema involves swelling in the larynx, which can be associated with life-threatening breathing difficulties.

Angiotensin Converting Enzyme Inhibitors (ACE Inhibitors)
See ACE Inhibitors.

In pharmacology, a drug that attenuates or even completely eliminates the effect of an agonist by blocking the site at which it binds to its receptor is called an antagonist. In doing so, the antagonist has no physiological effect of its own. The active substance icatibant is an antagonist that binds to the bradykinin B2 receptor, thereby inhibiting the effect of bradykinin.

Antifibrinolytic agent
An antifibrinolytic agent is a substance, such as a drug, that prevents the degradation of blood clots by inhibiting degradation of fibrin, an important component of the blood clot.

Antihistamines are drugs used, among other things, to treat allergies or anaphylactic shock. They bind to the receptor of the tissue hormone histamine, which is responsible for the symptoms of an allergic reaction, and attenuate or completely eliminate its effect.
Antihistamines have no effect on hereditary angioedema, as its symptoms are caused mainly by the peptide hormone bradykinin.

Autosomal inheritance
Autosomal inheritance is the inheritance of a characteristic (of a gene) via what are known as autosomes, of which there are 16 pairs, rather than the sex chromosomes.
Inheritance can be either dominant or recessive.

Brand name of C1-Inhibitor Concentrate marketed by CSL Behring.

Bradykinin is a naturally occurring peptide hormone that consists of nine amino acids and is formed locally in tissue. It is involved in the mediation of pain in the event of injury or inflammation. It increases the permeability of the vessels, dilates the blood vessels and causes smooth muscle to contract. In HAE, bradykinin is the key mediator for the development of swelling.

Bradykinin B2 receptor
The bradykinin B2 receptor is a molecule located in the membrane of cells in the vessel wall that binds the peptide hormone bradykinin. In doing so, bradykinin increases the permeability of the vessels. The drug icatibant can displace bradykinin from its receptor, thereby inhibiting its effect.

C1 esterase inhibitor
C1-esterase inhibitor is a protein that inhibits the activity of the enzyme C1-esterase. In types I and II HAE, there is either a C1-esterase inhibitor deficiency, or this enzyme does not function properly. These abnormalities are either congenital or acquired through spontaneous mutation of a gene on chromosome 11. If there is insufficient C1-esterase inhibitor activity, an increase in bradykinin concentrations can cause the typical symptoms of angioedema: swelling of the limbs, face, larynx and gastrointestinal tract.

C1 Inhibitor
An alpha-2-globulin that is synthesized in the liver and member of the serpin family of serine protease inhibitors. It is the only inhibitor of C1r and C1s, the classical complement pathway proteases. It also regulates kinin generation via inactivation of factors XIIa and plasma kallikrein, and intrinsic coagulation via inactivation of factor XIa.

C1 Inhibitor Antigenic
Quantitative levels of C1 inhibitor.

C1 Inhibitor Functional
Functional levels of C1 inhibitor.

A subunit of the C1 enzyme complex that activates the serum complement system. Low C1q could indicate a diagnosis of acquired angioedema.

C2 kinin
A vasoactive peptide generated by cleavage of the C2b fragment by plasmin. Early HAE research postulated that a C2 kinin may be involved in angioedema formation, but most investigators now believe the vasoactive peptide bradykinin is the primary mediator of angioedema attacks.

C4 Antigenic Levels
Quantitative levels of the fourth component of complement.

Brand name of the C1-Inhibitor Concentrate marketed by Sanquin.

Brand name of the C1-Inhibitor Concentrate marketed by Viropharma.

Patients with colic suffer from extremely painful cramps affecting various organs, e.g. the intestine, kidneys or gall bladder. The cramps are like contractions because periods of pain alternate with symptom-free periods.

Complement System
The complement system is an important part of the immune system. It consists of more than 22 proteins, which occur in soluble or cell-bound form in blood plasma. The complement system is involved in blocking pathogens like bacteria or fungi. However, it can also damage tissues if it gets out of control in certain disorders, such as some autoimmune disorders.

Contact System
Also known as the kallikrein-kinin generating system. The plasma proteins involved in the contact system are the proenzymes prekallikrein, factor XII (FXII or Hageman factor), and the non-enzymatic co-factor high molecular weight kininogen (HK). FXII autoactivates in the presence of negatively charged macromolecules like proteoglycans. Activated factor XII (FXIIa) then converts prekallikrein to kallikrein, which in turn digest HK to release bradykinin. Bradykinin binds to receptors on nearby endothelial cells causing vasodilatation and increased capillary permeability.

A contraceptive is a method of preventing pregnancy, e.g. the “pill”, which contains female sex hormones (estrogens and progestogens). The “pill” is also thought to be a trigger for type III hereditary angioedema.

An anabolic steroid in some countries used for HAE prophylaxis. However, be aware of the adverse effect profile of this drug.

De Novo Mutation
An alteration in a gene that is present for the first time in one family member as a result of a mutation in a germ cell (egg or sperm) of one of the parents or in the fertilized egg itself.

Dominant inheritance
With dominant inheritance, a genetic trait prevails, even if it is found in only one parent. The trait is expressed in all offspring. With recessive inheritance, both parents must be carriers for the trait to show in their offspring. An example of dominant inheritance is the inheritance of HAE.

A recombinant kallikrein inhibitor that inhibits kallikrein – an enzyme that plays a key role in the biochemical processes that lead to HAE-related swelling.

Edema is an accumulation of fluid in the tissues or body cavities. In HAE, fluid is released from the vascular system due to increased permeability of cell layers in the vessel wall.

Edema of the glottis
Edema of the glottis is a mostly acute and life-threatening swelling of the mucous membrane in the larynx.

Endothelial Cells
A simple squamous layer of cells that line the interior surface of blood vessels, forming an interface between circulating blood in the lumen and the rest of the vessel wall. Endothelial cells are involved in many aspects of vascular biology including vasoconstriction and vasodilation.

An enzyme is a protein that speeds up and controls biochemical reactions in the body. C1-esterase inhibitor (C1-INH) is an example of an enzyme.

Redness of the skin due to capillary dilation.

Estrogens are the most important female sex hormones. They are formed primarily in the ovaries and, to a lesser extent, in the adrenal cortex. There is a noticeable decline in estrogen production during and after the menopause. Use of estrogens is related with type III HAE.

Fibrinolytic System
Fibrinolysis is the process where a fibrin clot, the product of coagulation, is broken down. Its main enzyme, plasmin, cuts the fibrin mesh at various places, leading to the production of circulating fragments that are cleared by other proteinases or by the kidney and liver.

Factor XII (FXII)
Activated factor XII (also referred to as Hageman factor) is a contact system protease that is inactivated by C1 inhibitor.

Brand name of Icatibant the B2 receptor antagonist from Shire HGT. See also Icatibant.

Hepatic Adenoma
Benign liver cell tumors.

A state of toxic damage to the liver.

Hereditary means inherited and signifies the transfer of characteristics and traits to offspring. Certain disorders like HAE can also be inherited.

Histamine is a tissue hormone that is derived from the amino acid histidine and, among other things, plays an important role in allergic reactions. In cases of allergy, it is the main cause of symptoms like swelling, redness and itching.

A hormone is a messenger that is formed in glands and released into the blood stream for transfer to an organ or tissue, where it triggers certain effects by binding to its receptor.
Known examples of hormones are insulin and adrenaline.

i.v. stands for intravenous. An i.v. injection is, for example, the administration of a drug solution into a vein.

Icatibant, a peptidomimetic molecule consisting of 10 amino acids, is a selective antagonist of the bradykinin B2 receptor. By binding to this receptor, it inhibits the effect of the tissue hormone bradykinin, e.g. in HAE.

Idiopathic means independent, occurring with no identifiable cause. Idiopathic disorders are disorders of unknown cause.

In medicine and pharmacology, an inhibitor is a substance that delays or inhibits biochemical processes.

The incidence is the number of new cases of a certain disease in the population (see prevalence).

Intravenous Injection (i.v.)
See i.v.

Brand name for Dyax Corp. kallikrein inhibitor. See also DX-88.

See definition of contact system.

Larynx is the anatomical name for the voice box.

Laryngeal edema
Laryngeal edema is edema of the voice box (see edema of the glottis).

In medicine, the appearance of a disorder is known as manifestation.

In medicine, the development of diseases is known as pathogenesis.

A peptide is a molecule in which at least two and up to about 100 amino acids are linked by what are known as amide or peptide bonds. Peptides can have various effects on the human body. For example, bradykinin is a peptide that acts locally as a hormone.

A peptidomimetic is a peptide in which naturally and non-naturally occurring amino acids are linked by amide bonds. Among other things, peptidomimetics are used as drugs. For example, the bradykinin B2 receptor antagonist icatibant is a peptidomimetic.

Pharmacokinetics is concerned with how quickly and to what extent the active substance of an administered drug is absorbed by the body, reaches the blood stream and is excreted again.

An antihistame that is also used to treat nausea and vomiting or pain – and as a sedative or sleep aid.

A fibrinolytic enzyme inactivated by C1 inhibitor.

Prevalence indicates how many people in the population or in a certain section of the population suffer from a disease (see incidence).

An early symptom indicating the onset of an attack or disease.

In medicine, proliferation means the propagation and growth of tissue through cell division.

Measures that are taken in order to prevent diseases or their symptoms are known as prophylaxis.

Proteins are large biological molecules consisting of 100 to more than 1000 amino acids. The amino acids are linked by what are known as amide bonds. There are 15 amino acids present in humans and these can be linked to proteins in any order. Smaller protein compounds (< 100 amino acids) are called peptides.

Recessive inheritance
With recessive inheritance, both parents must be carriers for a certain trait to show in their offspring. If only one parent has the recessive trait, it can be concealed by a trait from the other parent in their offspring. Even if a recessive trait does not show, it can still be passed on (see dominant inheritance).

A recurrence is the reappearance of a disease or its symptoms after regression of a previous episode.

Brand name of the recombinant C1-Inhibitor Concentrate marketed by Pharming.

s.c. stands for subcutaneous. A s.c. injection is, for example, the administration of a drug solution under the skin.

Subcutaneous injection (s.c.)
See s.c.

In medicine, substitution means replacement of a deficient naturally occurring substance through external administration of this substance. For example, diabetics undergo insulin replacement if their pancreas stops producing insulin or fails to produce enough insulin.

The material or substance on which an enzyme acts.

Tissue hormone
A tissue hormone is a messenger that is produced in specialized individual cells and has a primarily local effect. Derivatives of amino acids such as histamine or small protein molecules (peptides) such as bradykinin are examples of tissue hormones.

A tracheotomy is an incision in the windpipe. It is performed as an emergency if there is a risk of suffocation due to blocked airways (e.g. during an episode of HAE in the larynx) or if a prolonged period of intubation is required.

Tranexamic acid
Tranexamic acid is a drug (antifibrinolytic agent) that prevents the breakdown of blood clots by inhibiting the fibrinolytic enzyme plasmin.

In medicine, an injury or physical damage caused by an external force is known as trauma.

Urticaria is another name for hives. In this disorder, an allergen (foods, drugs) causes red, itchy wheals to form on the outer layer of skin. Urticaria can also be caused by emotional stress or physical influences (cold, heat, pressure).

Vascular Permeability
A phenomenon affecting blood vessels relaxation or contraction. Relaxation leads to extravasation.

A phenomenon affecting blood vessels relaxation or contraction. Relaxation leads to extravasation.

Signs of masculinization that include increased body or facial hair, change in voice, clitoral enlargement and male-type baldness.

Generic name – Ondasetron – a selective 5-HT3 receptor antagonist that is used prevent nausea and vomiting.

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