Encyclopedia of Clinical Neuropsychology

2018 Edition
| Editors: Jeffrey S. Kreutzer, John DeLuca, Bruce Caplan


  • Martin HahnEmail author
  • Rohan Palmer
Reference work entry
DOI: https://doi.org/10.1007/978-3-319-57111-9_1862


Alterations; Alternate forms; Variant


Polymorphisms are alterations of genetic material that results in a variety of forms (alleles) that might take on different functional roles. Genetic polymorphisms result from several mechanisms. A common source of polymorphisms is mutations due to errors in DNA replications and repair. For example, replication slippage may cause variable number tandem repeat (VNTR) polymorphisms at microsatellites. Polymorphisms may also arise from exposure to mutagens (for e.g., radiation) in the external and internal environment.

Polymorphisms occur in different sizes. A single nucleotide polymorphism (SNP) is the result of a single base pair change. Larger alterations may result from restriction fragment length polymorphisms (RFLPs), simple sequence repeats (SSRs), or copy number variants (CNVs). Association studies employ genetic polymorphisms to identify genetic risks of disorders. For instance, several CHRNA5/A3/B4 polymorphisms have been...

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References and Readings

  1. Schlaepfer, I. R., Hoft, N. R., Collins, A. C., Corley, R. P., Hewitt, J. K., Hopfer, C. J., et al. (2008). The CHRNA5/A3/B4 gene cluster variability as an important determinant of early alcohol and tobacco initiation in young adults. Biological Psychiatry, 63, 1039–1046.CrossRefGoogle Scholar

Copyright information

© Springer International Publishing AG, part of Springer Nature 2018

Authors and Affiliations

  1. 1.Department of BiologyWilliam Paterson UniversityWayneUSA
  2. 2.Institute for Behavioral GeneticsUniversity of Colorado at BoulderBoulderUSA