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penetrance vs. expressivity

[pen-i-truhns] / ˈpɛn ɪ trəns /

noun

Genetics.
  1. the frequency, expressed as a percentage, with which a particular gene produces its effect in a group of organisms.

[ek-spre-siv-i-tee] / ˌɛk sprɛˈsɪv ɪ ti /

noun

  1. the quality or state of being expressive.

  2. Genetics. the degree to which a particular gene produces its effect in an organism.