Polygenic

Polygenic refers to a trait that is controlled by a group of non-allelic genes. This term is often used in genetics to describe a characteristic that is influenced by more than one gene. Examples of polygenic traits include skin color, height, and body mass index (BMI).

Overview

Polygenic traits are determined by the combined effects of multiple genes. These traits often show a wide range of phenotypes, or physical expressions, because they are influenced by the environment as well as by genes. This is in contrast to Mendelian traits, which are controlled by a single gene and typically show a simple pattern of inheritance.

Genetics of Polygenic Traits

The genes that contribute to polygenic traits are called quantitative trait loci (QTLs). Each QTL contributes a small amount to the overall phenotype. The combined effect of these QTLs, along with environmental influences, determines the final phenotype.

Polygenic traits often follow a normal distribution in populations, with most individuals showing an intermediate phenotype and fewer individuals showing extreme phenotypes. This is known as the bell curve.

Examples of Polygenic Traits

Many common traits are polygenic, including:

• Height: This is influenced by many genes, each of which contributes a small amount to overall height.
• Skin color: This is determined by multiple genes that control the production of melanin, the pigment that gives skin its color.
• Body mass index (BMI): This is influenced by genes that control metabolism, appetite, and other factors.

See Also

• Mendelian inheritance
• Quantitative trait locus
• Genetic variation

Polygenic Resources
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