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.
1 Other causes Thyroid gland disease and some types of inflammatory arthritis are more common in people with urticaria (hives) and angioedema. 2  In some people whose swellings persist for years without an obvious cause, an autoimmune process may be responsible.ngioedema is a condition in which small blood vessels leak fluid into the tissues, causing swelling. There is no known cure, but it may be possible to prevent the swelling with medications or occasionally diet. Allergy is a very rare cause of angioedema.