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In this sense, epistasis can be contrasted with genetic dominance, which is an interaction between alleles at the same gene locus. As the study of genetics developed, and with the advent of molecular biology, epistasis started to be studied in relation to quantitative trait loci (QTL) and polygenic inheritance.
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.
Environmental factors and other external influences can also play a role in phenotypic variation. Genetic architecture is a broad term that can be described for any given individual based on information regarding gene and allele number, the distribution of allelic and mutational effects, and patterns of pleiotropy, dominance, and epistasis. [1]
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 systematic approach to studying epistasis on a genome wide scale has significant implications for functional genomics. By identifying the negative and positive interactions between an unknown gene and a set genes within a known pathway, these methods can elucidate the function of previously uncharacterized genes within the context of a ...
The way in which the B and b alleles interact with each other to affect the appearance of the offspring depends on how the gene products interact (see Mendelian inheritance). This can include lethal effects and epistasis (where one allele masks another, regardless of dominant or recessive status).
The effects of dominance and epistasis are not reliably transmitted to progeny (see Mendelian inheritance, laws of segregation and independent assortment). This means that h 2 represents the phenotypic variation that is reliably passed from one generation to the next and which can be used to predict changes in mean fitness between generations.
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 ...