# confused.. hypo gene in beardies



## Tricky&TheFox (Nov 30, 2008)

As far as i know, for a beardie to ever produce hypos it must carry the hypo gene, either 2 copies or 1 - if a beardie has no hypo gene in either parent it is not capable of producing a hypo (visual) baby, it can only produce hets.

I've just been informed that the hypo gene can 'skip' a few generations and crop up down the line?! 

I don't understand how this can be possible, example, i've bred my rainbow tiger male (no hypo genes) to my female citrus het hypo leather (obv 1 gene), therefore the babies have a 25% chance of carrying the hypo gene from the female - am i correct so far?

now, the babies reach breeding age, and are put to a visual hypo - and you get no visual hypos whatsoever, therefore I would assume this baby does not carry the hypo gene.

according to what i've just read, the above would not be the case, and that the baby may carry the gene although it may never prove it by breeding??

This is what I read..(this is with a het hypo and het hypo pairing)

Yes that is right 25% are visuals, 50% will be 'typical' het and 25% just carriers as the hypo gene can be carried several generations and can still be thrown even if it has skipped some.

please tell me i'm not losing my mind :bash::bash:


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## paulh (Sep 19, 2007)

iona_gecko said:


> As far as i know, for a beardie to ever produce hypos it must carry the hypo gene, either 2 copies or 1 - if a beardie has no hypo gene in either parent it is not capable of producing a hypo (visual) baby, it can only produce hets.


I'm not up on hypo in bearded dragons. For the purposes of this discussion, I will accept that a hypo beardie can have either one or two copies of the hypo mutant gene in the gene pair.

If a beardie does not get a hypo gene from either parent, it is not a hypo and cannot produce hypo babies. A het hypo has a hypo mutant gene and a normal gene in the gene pair. These are one copy hypos and generally do not look normal.



iona_gecko said:


> I've just been informed that the hypo gene can 'skip' a few generations and crop up down the line?!


This may be a case of reduced penetrance.

"Penetrance is another variation in gene expression which is also influenced by internal or external factors. Sometimes the phenotype usually associated to with a certain genotype fails to appear at all. Such genes are said to have reduced pentrance. Penetrance is measured as the percent of cases in which the gene actually appears, compared to those known to possess the controlling genotype. A gene whose effects are always expressed has a penetrance of 100%, as with most blood groups. Many genes have a lower penetrance value. In chickens a recessive tremor mutant expresses the tremor only in 35% of those with the homozygous recessive genotype. The other 65% are normal! The 'action' of the mutant gene does not 'penetrate' to the end effect. Naturally, our expected Mendelian ratios are not observed in such situations." Wilmer Miller, A survey of genetics, p. 33 (see Wilmer Jay Miller's web site)

Or perhaps the pedigree data is incorrect.



iona_gecko said:


> I don't understand how this can be possible, example, i've bred my rainbow tiger male (no hypo genes) to my female citrus het hypo leather (obv 1 gene), therefore the babies have a 25% chance of carrying the hypo gene from the female - am i correct so far?


Not correct. If the female is a one copy hypo, then each baby has a 50% chance of getting the hypo gene. Most of these would be one copy hypos. If the female does not have a hypo gene, then none of the babies would be hypos.



iona_gecko said:


> now, the babies reach breeding age, and are put to a visual hypo - and you get no visual hypos whatsoever, therefore I would assume this baby does not carry the hypo gene.
> 
> according to what i've just read, the above would not be the case, and that the baby may carry the gene although it may never prove it by breeding??


This breeding test is good only for recessive mutant genes. As there are both one copy and two copy hypos, hypo is not a recessive mutant gene. And this test tells you nothing.



iona_gecko said:


> This is what I read..(this is with a het hypo and het hypo pairing)
> 
> Yes that is right 25% are visuals, 50% will be 'typical' het and 25% just carriers as the hypo gene can be carried several generations and can still be thrown even if it has skipped some.
> 
> please tell me i'm not losing my mind :bash::bash:


You are not loosing your mind; the quote is garbage. And it is garbage for all mutant genes.

100% penetrance:
het hypo (one copy hypo) x het hypo (one copy hypo) -->
25% two copy hypo
50% one copy hypo
25% normal (not carrier)

less than 100% penetrance:
het hypo (one copy hypo) x het hypo (one copy hypo) -->
25% two copy hypo
less than 50% one copy hypo
more than 25% normal looking. Most are normal; some are normal-looking carriers


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## Tricky&TheFox (Nov 30, 2008)

thanks, not entirely sure I've got that right *scratches head* het hypo is not visible in beardies and they look the same as normals so there's no way of telling without testing or proving out, only when there's two copies can you visually tell.

Oh very true, 50% chance not 25%, gah I did have an okay grasp of this til today *head desk*


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## paulh (Sep 19, 2007)

iona_gecko said:


> thanks, not entirely sure I've got that right *scratches head* het hypo is not visible in beardies and they look the same as normals so there's no way of telling without testing or proving out, only when there's two copies can you visually tell.
> 
> Oh very true, 50% chance not 25%, gah I did have an okay grasp of this til today *head desk*


A het hypo has a hypo gene paired with a normal gene. If these beardies look normal, then the hypo mutant gene is recessive to the normal gene. 

"Yes that is right 25% are visuals, 50% will be 'typical' het and 25% just carriers as the hypo gene can be carried several generations and can still be thrown even if it has skipped some."

This is still garbage. 25% would be visuals, 50% would be normal looking hets (carriers), and 25% normals (normal looking and not carriers)


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## Tricky&TheFox (Nov 30, 2008)

That's what I thought but then I was told that in the classifieds and it completely confused me


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## Gemstone Dragons (Jul 29, 2009)

paulh said:


> A het hypo has a hypo gene paired with a normal gene. If these beardies look normal, then the hypo mutant gene is recessive to the normal gene.
> 
> "Yes that is right 25% are visuals, 50% will be 'typical' het and 25% just carriers as the hypo gene can be carried several generations and can still be thrown even if it has skipped some."
> 
> This is still garbage. 25% would be visuals, 50% would be normal looking hets (carriers), and 25% normals (normal looking and not carriers)


The above is correct, perhaps my wording was wrong, what i was trying to explain is that once you have Hypo in a line it is near on impossible to breed it out and it takes several generations to completely take its effects out of a line - which is what i meant by it being found to skip generations.

For example, a clutch of babies i had, red citrus (no hypo gene visually for at least 3 generations) paired with a hypo trans female produced some babies showing the hypo gene effects visually.


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## Tricky&TheFox (Nov 30, 2008)

so the red citrus must have been het hypo for sure and carried on down the line?


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## Gemstone Dragons (Jul 29, 2009)

Ok got my pedigree records out for you......

That Red Citrus parents were -

Red citrus X Red citrus - no hypo gene.

Grandparents on mums side were -

Citrus X Red

Grandparents on dads side were -

Red citrus X Citrus (het Hypo)

The babies from him on his side had 1 grandparent het Hypo and 1 grt, grandparent visually Hypo.

So for my boy to be het Hypo it must have come from his 1 grandfather being het for it and skipped his dad.

1 great grandparent out of 8 was visually hypo making 1 grandparent out of 4 a het.

I had 3 clutches from that pairing and am keeping a record of any future pairings with him.

I am also not the first breeder this has happened too even with dragons several generations of their own breeding so knowing 100% what is behind them.

A true visual Hypo has every single nail clear, lots of dragons with some or half their nails clear, lighter shoulder pads or washed out/diluted/ fading colouring are produced showing the Hypo gene is behind them/strong in that breeding line.


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## Ssthisto (Aug 31, 2006)

Gemstone Dragons said:


> Ok got my pedigree records out for you......
> 
> That Red Citrus parents were -
> Red citrus X Red citrus - no hypo gene.
> ...


Except it didn't skip Dad - in that case, Dad was *also *het hypo and just plain nobody knew about it.


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## Gemstone Dragons (Jul 29, 2009)

So dad and then his boy used in this breeding are both het hypo?

Then how comes het hypo x visual hypo didn't produce any babies in 3 clutches with 100% clear nails - the only way to tell a true visual hypo?

Some of the babies had an odd couple of clear nails and the colour changed as a couple grew showing possible het signs but no visual 100% clear nailed hypo babies let alone 25% of each of those 3 clutches.

If the statistics were true and the father to the babies was het hypo 25% of those 3 clutches would have all had clear nails, that's clutches of 19, 21 & 23.

If the breeding was hypo trans x unknown het hypo by statistics about 15 of those babies would have had completely clear nails on every foot being definate visual hypos.


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## paulh (Sep 19, 2007)

Ssthisto said:


> Except it didn't skip Dad - in that case, Dad was *also *het hypo and just plain nobody knew about it.


That is the nature of recessive mutant genes. Het hypo x normal produces 1/2 normal looking het hypo and 1/2 normal. As both look normal, you can't tell what they are without a breeding test.

I had one case where a recessive mutant gene popped out after 5 generations. This sort of thing explains why recessive mutant genes are generally more common in the wild population than dominant or codominant mutant genes.


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## HadesDragons (Jun 30, 2007)

Right, there's a lot going on in this thread, and I'm going to try to address most of the main points - apologies if I miss one of them... Also, just a quick note that whenever I give percentages for a pairing, what I really mean is "on average you'll get x% of babies - I just don't want to keep writing it 

Going right back to the original post, for a pairing to produce visually Hypo babies (as in the two mutant copies, clear-nailed, lavender-padded visual Hypo), *both* parents must carry the gene. It's recessive so the beardie has to get a copy of the mutant Hypo gene from each parent - both must be either visually Hypo (two copies) or het Hypo (one copy).

The only exception to this is a novel mutation occurring at that gene locus, which is compatible with the Hypo gene, to produce similar effects. In practice you're likely talking odds in excess of a million to one (more likely 10-100 million to one or greater) per baby. For the purposes of this, we can pretty much ignore the odds of this happening.




The trouble is, "Hypo" as a trait (which I will refer to as "Lookalike Hypo") and "Hypo" as a gene (which I will refer to as "True Hypo") are more complex than that. I think the easiest way to explain is in pictures, so here are some photos to explain it.

These beardies are pretty much the same colour (and the same degree of paleness), but - if you look carefully - you'll see one has dark nails and one has clear; one is a "True Hypo" (left) and one is a "Lookalike Hypo" with dark nails (right):










"True Hypo" causes a reduction in the amount of melanin in the skin (making them paler), causes clear nails, lavender shoulder pads etc. It's inherited in a simple, Mendelian fashion (ie a beardie is either not Hypo at all, or het Hypo, or Homozygous Hypo)

"Lookalike Hypo" is what happens when you (or someone long before you) selectively breed for paleness. It causes a reduction of melanin in the skin, and can sometimes cause a few nails to be clear or paler than usual. It is polygenic (meaning lots of genes are involved - like with breeding for increased colour in beardies). A beardie can be a bit "Lookalike Hypo", a bit more "Lookalike Hypo", very "Lookalike Hypo" and so on. This trait has nothing to do with the simple "True Hypo" gene, other than looking similar.

The trouble begins when you consider that "Lookalike Hypo" - being unrelated to the single "True Hypo" locus - can be bred into the same beardie as the "True Hypo" gene. In effect you get the melanin-reduction effects of the "True Hypo" gene stacking with the melanin-reduction effects of the "Lookalike Hypo" trait. In its most extreme form, you'd get something like this:











Now, if you were to breed the beardie above to a completely non-Hypo dragon (ie it has no copies of the "True Hypo" gene), all of the babies would inherit a single copy of the "True Hypo" gene from the beardie above. This doesn't make a difference to them visually - thay'd have dark nails etc, but would still have "True Hypo" influence, in the sense that they could - if paired to the right dragon - produce visual, homozygous "True Hypo" babies. However, they'd also inherit a lot of the effects of the "Lookalike Hypo" trait, and would be paler than usual - probably looking similar to the beardie here:











That beardie's not a "True Hypo" (it has dark nails, doesn't have two copies of the "True Hypo" gene etc), but it's pale - to quote one breeder, it's "hypo'd to death" - I suspect that's the origin of:



Gemstone Dragons said:


> once you have Hypo in a line it is near on impossible to breed it out and it takes several generations to completely take its effects out of a line


and



Gemstone Dragons said:


> A true visual Hypo has every single nail clear, lots of dragons with some or half their nails clear, lighter shoulder pads or washed out/diluted/ fading colouring are produced showing the Hypo gene is behind them/strong in that breeding line.


The "True Hypo" gene can't be "weak" or "strong" - it's just a single gene. As far as I'm aware and anyone's proven there are only two alleles ("flavours") of the "True Hypo" gene - the normal, wild one, and the mutant "Hypo" one.

What "hypo'd to death" means is that - despite not being clear-nailed and despite not being a homozygous, visual "True Hypo" - it shows a lot of the effects of melanin reduction: paleness, muted, pastelly colours which wash out as the dragon ages etc etc.



Breeding one of those babies to another completely non-Hypo dragon would produce 50% of babies which are not het for "True Hypo". Keep one of those, and in the space of two generations, you've banished the "True Hypo" gene from the line. In the 50% of babies which are not het for "True Hypo", the "True Hypo" gene is gone. It's that simple and easy to remove "True Hypo" from a line. 

Incidentally, it's also that easy to add it back in again - breed one of the babies which is not het for "True Hypo" to a homozygous "True Hypo" and you'll get babies which are all het for "True Hypo". Breed any of those to a true Hypo and 50% of babies will be homozygous "True Hypos". 

Two generations to take it out of a line (ie to produce dragons which will *never* produce visually "True Hypo" babies, regardless of what they're paired to), two generations to stick it back in. Easy.



Now the "hypo'd to death" effect referred to above is actually caused by the "Lookalike Hypo" trait - most top-end "True Hypo" beardies (as with the near-pure-white one above) have a lot of "Lookalike Hypo" influence. As this is not simple Mendelian, and involves a lot of genes, it takes a long time and carefully-planned pairings to remove its effect from a line. This is nothing to do with the "True Hypo" trait - in our hypothetical line, this is long-gone, and won't be returning (unless we reintroduce it further down the line). We're still struggling with pale, washed out beardies, some of which may show the odd clear nail. This is not a sign that the beardies are het for "True Hypo" (we've already removed that from the line and proved it by breeding trials) - it's the effect of a lot of small genes reducing melanin production due to the "Lookalike Hypo" trait taking longer to be bred out of a line.

If you were to start with the very white beardie above and try to remove the effects of "Hypo" (in whatever form) from the line, you'd be waiting a long time. "True Hypo" would go quickly (two generations), but the effects of "Lookalike Hypo" would be present for a long time to come. "Lookalike Hypo" is the selective breeding which has gone on to make fairly pale "True Hypo" dragons into very pale "True Hypo" dragons.



As another illustration, this is what happens if you introduce "True Hypo" into a "dark" line:










You can see the clear nails, and she's a homozygous "True Hypo" who will produce "True Hypo" babies if appropriately paired, but - without the additional effects of the "Lookalike Hypo" trait from selective breeding - she's not very pale or exciting.

If you wanted to remove all melanin reduction from her line (ie both "True Hypo" and "Lookalike Hypo") and return to very dark beardies which have no trace of the "True Hypo" gene, you could probably do it in two generations - the time it takes to remove "True Hypo" as explained earlier. Despite it being the exact same "True Hypo" gene as the white beardie earlier, the effects of melanin reduction would be felt for a much shorter period of time in this line due to the lesser impact of the "Lookalike Hypo" trait.



There's a lot to take in there and it might be a bit confusing if you don't have a science background, but that's essentially what happens with Hypo lines. It also hopefully explains the "hypo'd to death" concept, and the residual consequences of introducing any pale Hypo dragon (which is likely both "True Hypo", with some effects of "Lookalike Hypo") into a non-Hypo line - even once the "True Hypo" gene is entirely removed, you may be seeing the effects of the "Lookalike Hypo" trait which was also introduced for generations to come.







iona_gecko said:


> so the red citrus must have been het hypo for sure and carried on down the line?


If it was to produce visual, clear nailed, Hypo babies then yes - barring the 10-100 million to one shot from right at the beginning, it's at least het Hypo.



Gemstone Dragons said:


> Ok got my pedigree records out for you......
> 
> That Red Citrus parents were -
> 
> ...


The dad would have been het Hypo if it arrived that way - it didn't "skip" him as single genes can't do that.




Gemstone Dragons said:


> So dad and then his boy used in this breeding are both het hypo?
> 
> Then how comes het hypo x visual hypo didn't produce any babies in 3 clutches with 100% clear nails - the only way to tell a true visual hypo?


Assuming the pedigree is correct and that the dad of iona_gecko's beardie was bred to a homozygous Hypo (remember, if you bred e.g. her beardie's dad's brother - a clutch mate - rather than her beardie's actual dad, it's only a 50% chance that the brother is actually het Hypo) without producing any homozygous Hypo babies, there are three possible explanations.

The first one (probably the more likely) is that the "True Hypo" gene carried by iona_gecko's beardie (if iona_gecko's beardie produced Hypo babies) actually came from the maternal side of Jo's pedigree - ie one of the mum's parents and grandparents and so on was het Hypo. The "True Hypo" gene didn't pass down the paternal line at all, so the dad of iona_gecko's beardie is not het Hypo, it's the mum who is instead. This explains why the dad didn't produce any Hypo babies when paired to a homozygous Hypo. Unless all of the beardies in the maternal line have been test-bred to het Hypo or homozygous Hypo beardies, the Hypo gene could have been passed along as a het - undetected - in that side of the line.

The second possibility is that Jo got unlucky in the test breeding: from het Hypo x homozygous Hypo there's a 50% chance of each baby being a visual, homozygous Hypo. That means there's also a 50% chance of each baby not looking Hypo, and being a het instead. 



Gemstone Dragons said:


> If the statistics were true and the father to the babies was het hypo *50%* of those 3 clutches would have all had clear nails, that's clutches of 19, 21 & 23.


The odds of 63 babies all coming out as het Hypo is the same as tossing 63 heads in a row with a coin - highly unlikely (a "big number with lots of zeros" to one chance), but still possible. Given the number of beardies being bred, it's got to happen to someone sooner or later.

I actually came close with a pairing a couple of years ago - I was breeding a homozygous Hypo het Trans to a homozygous Trans het Hypo (1/8 chance of getting a Hypo Trans per baby). From 68 babies I got two Hypo Trans beardies (1/34) - if you think about it, I was two babies away from getting no Hypo Trans babies at all in that pairing, despite a 1/8 chance per dragon. The odds are much more likely than getting 0/63 with a 50% chance per baby, but they're still fairly "extreme" odds. It goes the other way as well - I once got 17/21 Leatherbacks in a single clutch (50% chance per baby) - that's just the nature of chance.

The third chance is the one mentioned right at the start - that iona_gecko's baby had a novel mutation which is compatible with the "True Hypo" gene (10-100 million to one odds), making it het Hypo when neither of it's parents were.



Gemstone Dragons said:


> Some of the babies had an odd couple of clear nails and the colour changed as a couple grew showing possible het signs but no visual 100% clear nailed hypo babies let alone 25% of each of those 3 clutches.


I suspect that's the residual "hypo'd to death" effect caused by the "Lookalike Hypo" trait.


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## Tricky&TheFox (Nov 30, 2008)

thanks Hades that helped! It wasn't my bearded dragon we were discussing it was some dragons Gemstone is selling, used mine as an example but the breeding up there isn't for my dragon


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## Gemstone Dragons (Jul 29, 2009)

Thanks Andy, it was the 'hypo'd to death' bit I was meaning so thanks for explaining clearer the difference and how it's bred in/out, I was led to believe even 3-4 generations wouldn't necessarily breed it out and it could still crop up.


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## HadesDragons (Jun 30, 2007)

Gemstone Dragons said:


> Thanks Andy, it was the 'hypo'd to death' bit I was meaning so thanks for explaining clearer the difference and how it's bred in/out, I was led to believe even 3-4 generations wouldn't necessarily breed it out and it could still crop up.


It depends what the starting point is and what bloodlines you're putting into the line to try to remove the effects of "hypo'd to death". If you were trying to remove all traces of "paleness" (in whatever form), you could probably do it in the two generations it would take to remove "True Hypo" if you started with this line:











If you used this line as a starting point, it would probably take more than 3-4 generations (plus a lot of careful planning of pairings!) to remove all of the effects:











You also have to remember that as "Lookalike Hypo" is caused by the combined small effects of a lot of genes (and some of these will be recessive, some dominant, some co-dominant etc, just like the genes causing increased colour), the recessive and co-dom elements of "Lookalike Hypo" could potentially crop up again down the line (especially if you were keeping a "tight" line or during a backcross), even when "True Hypo" is long-gone from the line. 

If you had two dark-looking non-het Hypo beardies who both came from not-too-distant Hypo backgrounds, there's a reasonable chance you'd get a small percentage of pale babies from the pairing. This is due to these recessive/co-dom elements being passed down the line undetected and being carried by both parents (and not/barely influencing the parents visually). These recessive/co-dom "small-effect-paleness" genes then pair up in some of the babies to produce homozygous pairs, causing some/stronger visual effects (ie paleness) in those babies. 

The same can happen with increased colour - this is why two dark, dull beardies who have fairly recent colourful ancestors will often produce a small number of very bright, colourful babies when paired - the "red" or "yellow" genes which are recessive/co-dom can be passed along as hets without/barely influencing the carrier (hence the dark, dull parents), but if you get enough of them forming homozygous pairs in a baby, that baby will be colourful.


The "Lookalike Hypo" is the only bit of the Hypo morph (remembering that a typical Hypo morph dragon is "True Hypo" and also contains "Lookalike Hypo" traits) which can be "strong" or "weak". The "True Hypo" part of the morph is just a gene - it's either having a visual effect on the dragon (homozygous "True Hypo") or it's not (het "True Hypo" and "Wildtype"). It's the "Lookalike Hypo" trait which acts like a "modifier" and controls just how pale a beardie is.


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## Gemstone Dragons (Jul 29, 2009)

Nope you lost me on that bit lol

Will re-read it a few times in the morning 

That must be why a lot of the US breeders just use 'possible het' to describe their babies no matter what the pairing was, it covers their RS no matter what pops up or doesn't, known about or otherwise.


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## Ssthisto (Aug 31, 2006)

I think the basic explanation is:

1. Hypo (true hypo) is a single Mendelian recessive trait. It can hide in het form over generations without showing (if the heterozygous animal isn't bred to another het or homozygous animal, or the odds gods don't play fair in a clutch).
2. Lookalike hypo is a collection of many different genes that all combine to produce an animal that has reduced melanin. These individual little genes could be any combination of recessive (so you've got to breed two carriers/homozygous together to have visual babies), codominant (so a het is different to normal, but a homozygous is different to both normal and het) or even dominant (so hets and homozygous look the same) - but each individual gene has less of an effect by itself than the one "True Hypo" melanin reducing gene. It's the combination of all of the genes together that produces the Lookalike Hypo effect.


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