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 Hereditary angioedema (a serious genetic disorder that causes periodic swelling of the throat and other areas) 2  Mononucleosis (a type of viral infection)  Mumps (viral infection of the salivary glands in the neck)