# Whats the meaning of Het? or double het?



## RedTailBoa (Dec 29, 2009)

question is as the title says, what do they mean?!? thanks


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## pigglywiggly (Jul 19, 2008)

het stands or heterozygous, it means an animal carries a recessive colour

double het = carries two recessve traits


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## Jay_1987 (Oct 14, 2009)

Het means hetrozygous which means and animal carries a gene but Doesnt show it i.e. Its not visual.


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## reptile_man_08 (Jan 14, 2008)

And for it to become visual it must be homozygous, where there are two recessive genes.


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## imginy (Jun 14, 2009)

Here is a good sight I use for bearded dragons. Genetics
Yes as people said if it is het it only has half the gene needed and if its double het it will have half the gene for one trait and also half the gene for another.


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## MrMike (Jun 28, 2008)

pigglywiggly said:


> het stands or heterozygous, it means an animal carries a recessive colour
> 
> double het = carries two recessve traits





Jay_1987 said:


> Het means hetrozygous which means and animal carries a gene but Doesnt show it i.e. Its not visual.





reptile_man_08 said:


> And for it to become visual it must be homozygous, where there are two recessive genes.


Not true. Heterozygous means the animal carries two different alleles at the locus in question. An animal will visually express a dominant or codominant mutation when heterozygous for it.


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## Deano (Oct 26, 2006)

MrMike said:


> Not true. Heterozygous means the animal carries two different alleles at the locus in question. An animal will visually express a dominant or codominant mutation when heterozygous for it.


he he we got there eventually - het means 2 different genes at the same alle. So technically, a visual co-dominant morph, such as a pastal royal is HET pastel, but as the gene is co-dom, you can see it. If the animal has a pair of the mutent genes, it's homozygous. In the case of a co-dom gene, this is refered to the 'super' form - super pastal, which looks different again. For recessive genes, only the homozygous form looks different to normal.

'Het' is more commonly used when refering to recessive genes, such as Amel and Anery in Corn snakes. This is because an animal that is 'het' for a recessive trait does not show it visually, so the 'het' label is important to confirm the genetics that the animal is carrying. 

A het Amel corn looks normal, but has 1 amel gene (recessive), so we call it a het amel corn.

A het pastel Royal looks pastel, as its co-dom, so no-one says het pastel, they just refer to the visual morp and call it a pastal.

Double het means the animal has 2 different genes at 2 different alles (2 points in it's DNA strand). It might have 1 normal and 1 amel gene at 1 point, and 1 normal and 1 Anery at another point. Both these mutations are recessive so the animal looks normal, but it carries a double het - Amel and Anery - which is Snow, so this animal is 'double het snow'.


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## Ssthisto (Aug 31, 2006)

And if the original poster is interested in Boas, the most common "Double Het" you see out there is Hypo het Albino (AKA "Double het Sunglow") - Hypo is dominant so you SEE that if the snake is het for it; Albino is recessive, so that's "hidden" in heterozygous form.


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## RedTailBoa (Dec 29, 2009)

thanks for your inputs guys, is there a webpage, or a book i can get hold of to give me a comprehensive guide to all the differences and terms used for all these different morphs and gene differences n things? i need to start learning all this stuff it fascinates me


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## Ssthisto (Aug 31, 2006)

Have a look in the "Sticky" threads at the top of the Genetics forum - they should give you a pretty good overview 

http://www.reptileforums.co.uk/genetics/76499-genetics-questions-were-afraid-ask.html


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