Penetrance

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Penetrance is the percentage of the expression of the phenotype in an organism from its adjacent genotype [1] (e.g. how many members of a population with a specific genotype that show the expected phenotype).

An example of complete pentrance is neurofibromatosis type I. The symptoms of this mutation will be shown in all of the mutants - 100% penetrance. [2]

Incomplete penetrance is when some individuals with a particular (dominant) mutation express a wild type phenotype. An example is polydactyly.

Reference

  1. Hartl, D.L., Ruvolo, M. (2012) Genetics:Analysis Of Genes And Genomes, United States of America: Jones and Bartlett
  2. NHS. (ND). Penetrance. Available at: http://www.geneticseducation.nhs.uk/genetic-glossary/221-penetrance (Accessed at: 26/11/14)