Chromosome
A chromosome, or chromosome body, is a long, continuous strand of DNA that contains genes and regulatory elements. It is a macromolecular unit of genetic information. Humans had twenty-three chromosome pairs.

Chromosomes could be negatively impacted by:
excess or deficiency of trace elements
industrial waste byproducts in air and water
vitamin deficiencies
viral contaminants
magnetic field failure
increase in visible light
potassium overexposure
calcium resorption
bad personal hygiene
red dye number two
long-term disease exposure
extraterrestrial diseases
airborne particles (inert or carcinogenic)
gravitational variations
solar flux variations
neutrino bombardment
chemical exposure
nuclear radiation
gamma ray exposure
ultraviolet radiation
parasitic organisms ( okudagram)

In 2364, Doctor Beverly Crusher claimed that chromosomal damage was preventing the Aldeans from conceiving and also explained their lack of appetite, extreme pallor, and sensitivity to light. ()

In 2369, Julian Bashir and Jadzia Dax ran a chromosome scan of a clone of Ibudan. ()

In 2372, The Doctor used undamaged chromosomes from Danara Pel's cerebellum to recreate her original DNA code. ()

When the Silver Blood  and its crew began to deteriorate from subspace radiation in 2375, The Doctor found that their chromosomes were breaking down on a molecular level. ()

The Brunali made microgenetic alterations in the 3rd, 13th, and 17th chromosomes of certain children so that they would produce a spaceborne virus, turning them into weapons against the Borg. ()

During an away mission in the  in 2376, Mortimer Harren asserted that genetics, not environment, were the determining factor in personality. In response, Captain Janeway jokingly asked, "How's your thirteenth chromosome? Missing a couple of base pairs in gene 178?" ()

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