Monosomies

Part of speech: noun

Definitions

1. A genetic condition characterized by the presence of only one copy of a particular chromosome instead of the usual pair
2. A type of chromosomal abnormality resulting in a single chromosome rather than a homologous pair
3. The occurrence of having a single chromosome that typically exists in duplicate within the genetic makeup of an organism

Etymology: Monosomy is a compound built from two Greek elements: "mono-", meaning "single" or "alone," and "-soma", meaning "body." In genetics, "soma" is the standard term for the body's non-reproductive cells, which is why a cell's chromosomal makeup is described in these terms. The word "chromosome" itself combines Greek "chroma" (colour) with "soma" (body), since chromosomes take up stain so readily under the microscope. The "-some" ending in "monosomy" thus links back to the same Greek root, and the word belongs to a family of cytogenetic terms such as "trisomy," where a chromosome appears three times instead of twice. "Monosomy" was formed in the early twentieth century, once cytogenetics had made it possible to count chromosomes, so it is a modern scientific coinage from classical roots rather than a word the Greeks used.