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Non-allelic or non-alletic

I stumbled across the term in my Human Genetics textbook. It didn't explain it there, and a quick google search only showed scientific papers that refer to 'recombinations with non-allelic genes' without explaining what they are.

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The term non-allelic gene refers to a gene that has no dominant or recessive allele. – Hyacinth James Mar 4 at 10:19

It is my understanding that a non-allelic gene is one that affects another's traits, but is not as a typical dominant / recessive manner. If I am correct, this is the same thing as epistasis - meaning that one gene modifies how another is expressed. There exists epistatic genes for horse coat color. One gene is the coat color itself (horses may have either brown or red color alleles at this loci), the second gene is for a protein that allows the coat color gene to be expressed. For example, a horse has two brown alleles at the coat color locus. It also has a wild type gene in the second (modifier) position. This modifier allows the color brown to be expressed and the horse is brown. B/B, wt/wt --> Brown If the horse has the two brown alleles, but has a mutant allele at the modifier position, then coat color is not expressed and the horse is white. B/B, mt/mt --> white

Because the modifier alleles are separate genes from the coat color alleles, the two are non-allelic - yet they both affect the same trait in some way.

I hope this helps.

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+1 This is also my understanding of terdon's link. I would argue that the name non-allelic gene is very poorly chosen though. Theoretically speaking there might not have any single gene that does not affect the phenotypic expression of other genes. And of course a non-allelic gene can be a non-allelic gene only if it is polymorphic (and have multiple alleles)! – Remi.b Nov 28 '13 at 8:04

The context of the term "non-allelic" is non-allelic recombinations which means recombinations between genes that are not exactly alleles but have enough sequence homology to permit recombination.

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Is sequence homology needed for recombination? – One Face Feb 17 '15 at 8:19
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@CRags For homologous recombination, yes. Even for other kinds of recombination (for e.g. VDJ) there is a stretch of sequence that acts as a homologous block. – WYSIWYG Feb 17 '15 at 9:08
    
Thanks for clarification – One Face Feb 17 '15 at 9:22

My understanding of it got me to the point that non-allelic recessive means a single allele can show its effect in the complete absence of its partner; whether it is a dominant or recessive - as in the case if hemophilia. Because at the molecular level normally we define a recessive allele as that which cannot encode any enzyme. Help me to get through this.

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Some of the information contained in this post requires additional references. Please edit to add citations to reliable sources that support the assertions made here. Unsourced material may be disputed or deleted.

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Well done for your first post. If you can, please do add some information sources to back up what you have said here :) – L.B. Feb 16 '15 at 18:33

Alleles of two or more independent genes interact to produce a phenotypic expression different from normal expression

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We're looking for long answers that provide some explanation and context. Don't just give a one-line answer; explain why your answer is right, ideally with citations. Answers that don't include explanations may be removed.

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Answers should be longer than a single sentence and should provide references and citations where necessary. Please consider editing your answer as in its current form, it will likely receive Close Votes. – AMR Nov 29 '15 at 17:37

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