Definition
Allele is an alternate form of a gene, which is the basic unit of inheritance. A gene is located at a particular site on the chromosome and can have several alleles for that locus. For example, A, B, and O are different alleles for the ABO blood-type marker locus of a gene. Alleles greatly influence the expression of physical and behavioral phenotypes or traits such as eye color. For instance, the apolipoprotein E (APoE) gene is a well-known risk factor for developing Alzheimer’s disease. The APoE gene has three common alleles: epsilon 2, epsilon 3, and epsilon 4. There is some evidence that carriers of the APoE epsilon 4 allele are at a greater risk for the development of Alzheimer’s disease. In contrast, the APoE epsilon 3 allele has been suggested as a “protective” factor in the development of Alzheimer’s disease (Plomin et al. 2003).
Cross-References
This is a preview of subscription content, log in via an institution.
Buying options
Tax calculation will be finalised at checkout
Purchases are for personal use only
Learn about institutional subscriptionsReferences and Readings
Plomin, R., Defries, J. C., Craig, W., & McGuffin, P. (2003). Behavioral genetics in the postgenomic era. Washington, DC: American Psychological Association.
Author information
Authors and Affiliations
Corresponding author
Editor information
Editors and Affiliations
Rights and permissions
Copyright information
© 2018 Springer International Publishing AG, part of Springer Nature
About this entry
Cite this entry
DeLuca, J. (2018). Allele. In: Kreutzer, J.S., DeLuca, J., Caplan, B. (eds) Encyclopedia of Clinical Neuropsychology. Springer, Cham. https://doi.org/10.1007/978-3-319-57111-9_1855
Download citation
DOI: https://doi.org/10.1007/978-3-319-57111-9_1855
Published:
Publisher Name: Springer, Cham
Print ISBN: 978-3-319-57110-2
Online ISBN: 978-3-319-57111-9
eBook Packages: Behavioral Science and PsychologyReference Module Humanities and Social SciencesReference Module Business, Economics and Social Sciences