As a result of the current Federal government funding situation, the information on this website may not be up to date or acted upon.

The NIH Clinical Center (the research hospital of NIH) is open. For more details about its operating status, please visit https://cc.nih.gov.

Updates regarding government operating status and resumption of normal operations can be found at https://www.opm.gov.

NCI Dictionary of Genetics Terms

  • Resize font
  • Print
  • Email
  • Facebook
  • Twitter
  • Google+
  • Pinterest

The NCI Dictionary of Genetics Terms contains technical definitions for more than 200 terms related to genetics. These definitions were developed by the PDQ® Cancer Genetics Editorial Board to support the evidence-based, peer-reviewed PDQ cancer genetics information summaries.

Browse:
polymorphism
(PAH-lee-MOR-fih-zum)
A common mutation. “Common” is typically defined as an allele frequency of at least 1%. All genes occur in pairs, except when x and y chromosomes are paired in males; thus a polymorphism with an allele frequency of 1% would be found in about 2% of the population, with most carriers having one copy of the polymorphism and one copy of the normal allele.