Pleiotropy: Definition, Overview, Meaning, Examples, Topics

Pleiotropy is the phenomenon where a pleiotropic gene results in several, sometimes unrelated, phenotypic traits of an organism. Pleiotropy is very important in biology since it indicates the complexity of the relationship of genetic interaction, one gene affecting several aspects of the growth and functions of an organism. Pleiotropy is important for fields like genetics and medicine, as it helps in understanding the interdependence of genes and traits in the human body. This important part of the unit genetics in biology.

Latest: NEET 2024 Paper Analysis and Answer Key 

Don't Miss: Most scoring concepts for NEET | NEET papers with solutions

New: NEET Syllabus 2025 for Physics, Chemistry, Biology

NEET Important PYQ & Solutions: Physics | Chemistry | Biology | NEET PYQ's (2015-24)

This Story also Contains

1. What is Pleiotropy?
2. Gene Pleiotropy
3. Examples of Pleiotropy
4. Human Genetic Disorders

What is Pleiotropy?

Pleiotropy is one of the phenomena by which one gene, termed a pleiotropic gene, influences several apparently unrelated phenotypic traits. This involves higher complexity in the interaction of genes and their impacts on an organism.

It provides wider applications in understanding evolutionary biology, medicine, and genetic engineering. An example of classic pleiotropy is the gene causing sickle cell anaemia. It is somehow related to the shape of the blood cells and resistance to malaria.

Also Read

• Principles Of Inheritance And Variation MCQs

• Mendelian Disorders

• Molecular Basis Of Inheritance

• DNA

Gene Pleiotropy

Pleiotropy is the phenomenon where the pleiotropic gene affects several phenotypic traits because of the influence of the product of the gene on various biological pathways. For example, an allele of a single gene may cause widespread effects on many tissues or organs. An example of pleiotropy is the gene associated with sickle cell anaemia, which also causes effects on malaria resistance.

On the other hand, polygenic traits are influenced by several genes working together. Each gene contributes a little effect to the overall phenotype. Human height and skin colour are examples of this category. While pleiotropy emphasizes the concept of how one gene can influence multiple traits while polygenic inheritance explains how many genes work together to influence a single trait. This distinction makes clear the complexity surrounding genetic interaction and can explain how phenotypes are shaped.

Examples of Pleiotropy

These examples are:

Phenylketonuria (PKU)

Phenylketonuria (PKU) is an autosomal recessive disease which results from PAH gene mutations and hence no production of phenylalanine hydroxylase enzyme. This leads to intellectual disability, behavioural issues, eczema, and a strange smell which may work to describe how one gene mutation has the potential to cause multiple different traits.

Sickle Cell Anemia

Sickle cell anemia is associated with a defect in the HBB gene resulting in the production of red blood cells that are difficult to shape. HbS results from a single mutation and directly produces anaemia, and pain crises, is prone to infections, and organ damage and is an excellent example of pleiotrophy.

Human Genetic Disorders

Pleiotropy does manifest in a variety of human genetic disorders. A mutation in a gene here leads to multiple effects across different parts of the body. For example, FBN1 gene mutations lead to Marfan syndrome, which includes manifestations in the skeleton and the heart and even some defects in the eyes. NF1 is another disorder its loss of function of the NF1 gene has both skin and nerve tumours as well as cognitive difficulties.

These conditions explain the phenomenon of pleiotropism, where one pleiotropic gene causes multiple, often unrelated, phenotypic effects. This puts clearly into vision that genetic influences within the body can sometimes be remarkable, and that mutation of a single gene can have extensive effects on different body systems.

Also Read