by Anne Marie Helmenstine, Ph.D. Updated June 13, 2014. Definition: A molecular orbital is an orbital or wavefunction of a molecule's electron. Electrons around a molecule can be associated with more than one atom and are often expressed as a combination of atomic orbitals.
Hereditary angioedema is a disorder characterized by recurrent episodes of severe swelling (angioedema). The most common areas of the body to develop swelling are the limbs, face, intestinal tract, and airway. Minor trauma or stress may trigger an attack, but swelling often occurs without a known trigger.
Angioedema is a swelling of the deeper layers of the skin, subcutaneous tissues and the tissues immediately underlying mucous membranes, or submucosal tissue. Most cases of angioedema result from an allergic-type reaction that results in vascular leakage, which causes submucosal swelling. The lips, tongue, larynx and face are often involved. Oftentimes, foods, medications, insect bites, pollen and similar allergens can cause such a reaction. Over the past two decades, it has become widely known that ACE inhibitors, a class of the most commonly prescribed antihypertensive medications, can also cause angioedema in patients who are predisposed.