Dictionary

evolution, cultural See cultural evolution.

evolutionarily conserved gene A gene that has remained essentially unchanged throughout evolution. Conservation of a gene indicates that it is unique and essential: There is not an extra copy of that gene with which evolution can tinker, and changes in the gene are likely to be lethal.

evolutionarily conserved sequence A base sequence in a DNA molecule (or an amino acid sequence in a protein) that has remained essentially unchanged throughout evolution.

Ewing sarcoma See sarcoma, Ewing.

exacerbation A worsening. In medicine, exacerbation may refer to an increase in the severity of a disease or its signs and symptoms. For example, an exacerbation of asthma might occur as a serious effect of air pollution, leading to shortness of breath.

exaggerated startle disease See hyperexplexia.

exam, pelvic See pelvic exam.

exam, rectal See digital rectal exam.

exanthem A rash on the outside of the body. By contrast, a rash on the inside of the body (for example, inside the mouth) is called enanthem. A patient with measles can have both exanthem and enanthem. See also enanthem; measles; rash.

exanthem subitum A sudden rash. See also measles.

excess iron An overload of iron that can damage the heart, liver, gonads, and other organs. See also iron excess.

excise To cut out entirely. For example, a scalpel or laser beam may be used to excise a tumor. The terms excise and resect are not synonymous. Excise implies total removal, whereas resect does not.