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A polygene is a member of a group of non-epistatic genes that interact additively to influence a phenotypic trait, thus contributing to multiple-gene inheritance (polygenic inheritance, multigenic inheritance, quantitative inheritance [1]), a type of non-Mendelian inheritance, as opposed to single-gene inheritance, which is the core notion of Mendelian inheritance.
In Mendelian inheritance, genes have only two alleles, such as a and A. Mendel consciously chose pairs of genetic traits, represented by two alleles for his inheritance experiments. In nature, such genes often exist in several different forms and are therefore said to have multiple alleles. An individual usually has only two copies of each gene ...
Polygenic inheritance can be explained as Mendelian inheritance at many loci, [9] resulting in a trait which is normally-distributed. If n is the number of involved loci, then the coefficients of the binomial expansion of ( a + b ) 2n will give the frequency of distribution of all n allele combinations .
This model illustrates polygenic additive effects on phenotype Genetic effects are broadly divided into two categories: additive and non-additive. Additive genetic effects occur where expression of more than one gene contributes to phenotype (or where alleles of a heterozygous gene both contribute), and the phenotypic expression of these gene(s ...
Eye color is an example of a (physical) phenotypic trait. A phenotypic trait, [1] [2] simply trait, or character state [3] [4] is a distinct variant of a phenotypic characteristic of an organism; it may be either inherited or determined environmentally, but typically occurs as a combination of the two. [5]
Autosomal dominant A 50/50 chance of inheritance. Sickle-cell disease is inherited in the autosomal recessive pattern. When both parents have sickle-cell trait (carrier), a child has a 25% chance of sickle-cell disease (red icon), 25% do not carry any sickle-cell alleles (blue icon), and 50% have the heterozygous (carrier) condition. [1]
The infinitesimal model, also known as the polygenic model, is a widely used statistical model in quantitative genetics and in genome-wide association studies.Originally developed in 1918 by Ronald Fisher, it is based on the idea that variation in a quantitative trait is influenced by an infinitely large number of genes, each of which makes an infinitely small (infinitesimal) contribution to ...
Research on ecologically important traits often focuses on single alleles. [17] However, it has been found that in many cases, phenotypes have a polygenic basis - they are controlled by many different alleles. Complex traits in particular are more likely to have a polygenic basis. [18]