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Polygenic trait

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A trait that is controlled by a group of nonallelic genes (called polygene)


Polygenic traits are controlled by two or more than two genes (usually by many different genes) at different loci on different chromosomes. These genes are described as polygenes. A polygene refers to a group of genes that when expressed together produce a particular phenotype or trait. Multiple genes are involved for a particular trait to manifest. In humans, height, skin colour, and weight are determined by multiple genes that are expressed together. Polygenes allow a wide range of physical traits. For instance, height is regulated by several genes so that there will be a wide range of heights in a population. Accordingly, there are more than 400 genes at play in determining the height of an adult human apart from the non-genetic factors (e.g. nutrition) that influence the trait. The predisposition to type 2 diabetes is believed to be associated with polygenes.

Since there are several genes are at play in determining a trait, Mendelian inheritance alone may not explicate the phenotype of an organism. A phenotypic ratio where the effect of a single gene can be predicted would therefore not apply to polygene expression.

Word origin: poly ("many") + genic ("of genes")

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