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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.
A trait can also be determined by multiple genes, known as polygenic inheritance. Genes also have different levels of penetrance, which determines how much they will be expressed. In addition, the environment affects the expression of numerous genes, therefore making the test cross inapplicable in many cases.
At present the best-understood examples of polygenic adaptation are in humans, and particularly for height, a trait that can be interpreted using data from genome-wide association studies. In a 2012 paper, Joel Hirschhorn and colleagues showed that there was a consistent tendency for the "tall" alleles at genome-wide significant loci to be at ...
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 ...
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 .
In fact, the terms 'multifactorial' and 'polygenic' are used as synonyms and these terms are commonly used to describe the architecture of disease causing genetic component. [2] Multifactorial diseases are often found gathered in families yet, they do not show any distinct pattern of inheritance.
Phenotypes may be predicted with at least better-than-chance accuracy using a Punnett square, but the phenotype that may appear in the presence of a given genotype can in some instances be influenced by many other factors, as when polygenic inheritance and/or epigenetics are at work.
Human genetics is the study of inheritance as it occurs in human beings.Human genetics encompasses a variety of overlapping fields including: classical genetics, cytogenetics, molecular genetics, biochemical genetics, genomics, population genetics, developmental genetics, clinical genetics, and genetic counseling.