Penetrance is the percentage of the expression of the phenotype in an organism from its adjacent genotype  (e.g. how many members of a population with a specific genotype that show the expected phenotype).
Incomplete penetrance is when some individuals with a particular (dominant) mutation express a wild type phenotype. An example is polydactyly.
- ↑ Hartl, D.L., Ruvolo, M. (2012) Genetics:Analysis Of Genes And Genomes, United States of America: Jones and Bartlett
- ↑ NHS. (ND). Penetrance. Available at: http://www.geneticseducation.nhs.uk/genetic-glossary/221-penetrance (Accessed at: 26/11/14)