Find definitions for terms related to hereditary angioedema (HAE)

ACE inhibitor: Class of medicines used to treat high blood pressure and other diseases.

Activating factor: A functioning plasma protein that works in the coagulation pathway to help form a clot.

Anabolic steroid: Also referred to as attenuated androgen, a class of steroid hormones used to prevent HAE attacks. Although their mechanism of action in HAE patients is unknown, these agents are believed to partially reverse the biochemical defect by increasing levels of C1-esterase inhibitor (C1-INH), helping to prevent angioedema attacks in patients with inherited C1-INH deficiency.

Bradykinin: A protein, which when released, causes blood vessels to expand (dilate) and leak fluid, such as serum, into surrounding tissue.

C1 inhibitor: Also referred to as C1-INH, a protein found in the fluid part of your blood that controls C1, a component of your body's complement system. Abnormal swelling can result when C1-INH is insufficient or defective.

Cleave: To cut; to split

Edema: Swelling caused by an excessive amount of fluid in the body tissues.

Enzyme: A protein that changes the rate of chemical reactions in the body.

Hereditary angioedema, or HAE: A rare, hereditary disease of the immune system that affects an estimated 1 in 50,000 adults and children globally. HAE causes attacks of spontaneous swelling that are often painful and severe, and can be life-threatening.

High-molecular-weight kininogen (HMWK): HMWK, a protein that acts on the inflammation and coagulation processes; inactive until it is cleaved by kallikrein and in turn, releases bradykinin.

Inhibitor: That which reduces, prevents, or stops; i.e., a substance that stops enzyme activity.

Kallikrein–kinin system: A system of proteins in the blood that has a role in the inflammatory pathway; through this system, bradykinin is released.

Kinin: A protein that is a component of the kallikrein-kinin system.

Laryngeal attack: An HAE attack that affects the larynx (throat); this can block or close the airway, leading to difficulty breathing and, potentially, death.

Plasma kallikrein: An enzyme present in blood plasma, urine and tissue; responsible for cleaving high-molecular-weight kininogen (HMWK), which then releases bradykinin.

Prekallikrein: Precursor to kallikrein; inactive until it's cleaved by an activated factor (specifically, activated factor XII) to generate active kallikrein.

Preventative therapy: In HAE, medicine taken to prevent attacks.

Subcutaneous: Beneath the skin

Trigger: In HAE, something that causes an attack. Stress and trauma are two common HAE attack triggers.