Definition of Pleiotropy



Pleiotropy is a phenomenon that happens when a gene has an influence on two or more than two phenotypic traits that are not much related to each other. This type of gene that expresses multiple phenotypes is termed as a pleiotropic gene. If there occurs a mutation in this kind of gene, then multiple traits get affected consequently.

 


This phenomenon occurs due to several mechanisms that overlap one another. The mechanisms include gene pleiotropy, selectional pleiotropy, and developmental pleiotropy.

 


Example of Pleiotropy:

One of the inherited disorders known as phenylketonuria is an example of pleiotropy. The level of phenylalanine increases in the body due to the deficiency of an enzyme, phenylalanine hydroxylase. This deficiency happens due to an affected gene that is located on chromosome 12 and it is not able to produce the very enzyme. The amino acid is unable to get metabolized and hence stores in the body and causes mental retardation.

 

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