Genetics peeps blue greying out?

[ycbm]

Hi guys, friend is interested in the possible genetics of her horse. He was a blue and white as a youngster and is gradually greying out but quite late and quite slowly.

Is there anything different about a blue and white that greys out from a piebald black and white that greys out? He was, from his early photos, never black and white but genuine blue.
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[poiuytrewq]

Hi guys, friend is interested in the possible genetics of her horse. He was a blue and white as a youngster and is gradually greying out but quite late and quite slowly.

Is there anything different about a blue and white that greys out from a piebald black and white that greys out? He was, from his early photos, never black and white but genuine blue.
.

Interesting question. My Shetland was very much blue and white, he’s now definitely pure white/grey

 

[[153312]]

When you say 'early' photos, how early?

Grey is a disorder of the melanocytes, the pigment producing cells, so they overproduce pigment at first leading to hyperpigmentation in youngsters then gradually the cells die off/stop producing pigment. Can't remember the molecular basis of it but irrc something to do with magnesium movement into cells......

The blue hue on modified black based horses is usually a result of white hairs interspersed and changing the wavelength of light that is reflected from the patches of pigment. So the melanocytes in some hairs/some areas of the individual hair shafts have stopped melanin synthesis before those around them and there's all or fully white hairs mixed in with darker ones to give the appearance of blue light being reflected. That is how you get blue roans, and also how you get things like 'blue' in other animals, e.g. fish - there's black pigment there, not blue, under a layer of white that changes the wavelength reflected off the scales, and I'd presume it's a similar process in horses, as both are melanin which gives the black pigments, though hair doesn't have guanine but non pigmented hair is white anyway....

hope i'm not talking bs here

 

[I'm Dun]

He could have some sort of sabino or W gene which gives the impression of roan. He could actually be roan. He could have Lp or similar. He could have just started to grey out early. Without photos its impossible to say.

 

[[153312]]

Oh I am talking bullshit ID has just brought up a lot of possibilities I never even considered ???

 

[Lois Lame]

I don't know, Cowrie, I thought your post was great.

 

[poiuytrewq]

Sounded good to me too!

 

[chaps89]

So, silly question alert, and apologies OP for going off on a tangent -
Is the white hair you get on a piebald/skewbald genetically (?) different to a ‘grey’ horse which is white as opposed to grey?
Is that why greys get melanoma problems but coloureds don’t tend to?

 

[[153312]]

So, silly question alert, and apologies OP for going off on a tangent -
Is the white hair you get on a piebald/skewbald genetically (?) different to a ‘grey’ horse which is white as opposed to grey?
Is that why greys get melanoma problems but coloureds don’t tend to?

Yes and no.

The white hair is unpigmented in both. It's the mechanism underlying the lack of pigment that is different. White patches that have never had colour dont have functioning melanocytes at all but greys have done in the past (and some do start producing pigment again which is why you get fleabites).
Greys have melanoma because of a duplication of a short bit of DNA in a gene that mostly controls downstream signal cascades. (Basically how cells/things in cells talk to each other - one cell sends out a molecule that binds to the outside of another one, this changes the conformation of the thing it binds to and changes how that interacts with stuff inside the other cell.... Etc etc you get the idea.) So they stop behaving as they ought to and effectively stop following instructions.

Really reductionist explanation oops ... I'm procrastinating... ?

 

[[153312]]

Though it should be easy to test my white/blue theory by just looking at the animals hair lol and/or putting coloured lenses on

 

[PinkvSantaboots]

My friend has a blue and white chaps registered show pony mare and her blue bits are definitely getting lighter, she looks more like a grey than a coloured although I think in the ring she often really stands out, she has won alot in coloured classes so I think judges do really like her and moves beautifully ?

I think she is 9 now but her dark bits have definitely faded.

 

[rabatsa]

As greying out rates vary from horse to horse I doubt that the base colour has much to do with it. I bought a bay 2 yr old that had a star and one white sock, no giveaway goggles or anything, he did not start to show any signs of greying out until he was a 4yr old and it really speeded up a couple of years later until by the time I last saw him as a 12 yr old he only had dark grey patches on his knees and hocks on an otherwise white pony.

 

[shortstuff99]

@Cowrie I hope you're going to carry on academia into genetics!

 

[Hackback]

As I guess grey is a gene that sits on top of the colour genes it can go with any colour. We have a blue roan on the yard that is greying out. He is genetically blue roan but that damn grey gene that he got from his mother still got him. Grey genes are a nuisance and ought to be banned!

 

[I'm Dun]

Oh I am talking bullshit ID has just brought up a lot of possibilities I never even considered ???

I've got a blue dog so also found it interesting, even though I have no idea how colour genetics work in dogs other than blue is a form of dilute

 

[Gloi]

The first question it will depend on the colour as a foal whether born black/white or blue roan/white. My friends Shetty was blue/white as a weanling but will have been born black/white. He went all white as he aged.
@Cowrie something you may find interesting to investigate is the effect of grey on double dilute horses and their rate of developing melanoma. I knew a double dilute with grey who developed multiple melanoma at a young age as the grey developed and thought it might be an interesting thing to look into.

 

[[153312]]

The first question it will depend on the colour as a foal whether born black/white or blue roan/white. My friends Shetty was blue/white as a weanling but will have been born black/white. He went all white as he aged.
@Cowrie something you may find interesting to investigate is the effect of grey on double dilute horses and their rate of developing melanoma. I knew a double dilute with grey who developed multiple melanoma at a young age as the grey developed and thought it might be an interesting thing to look into.

I knew TRPM1 was protective against melanoma (the gene that is responsible for the leopard complex), but will have a look into double dilutes, thank you

 

[chaps89]

Yes and no.

The white hair is unpigmented in both. It's the mechanism underlying the lack of pigment that is different. White patches that have never had colour dont have functioning melanocytes at all but greys have done in the past (and some do start producing pigment again which is why you get fleabites).
Greys have melanoma because of a duplication of a short bit of DNA in a gene that mostly controls downstream signal cascades. (Basically how cells/things in cells talk to each other - one cell sends out a molecule that binds to the outside of another one, this changes the conformation of the thing it binds to and changes how that interacts with stuff inside the other cell.... Etc etc you get the idea.) So they stop behaving as they ought to and effectively stop following instructions.

Really reductionist explanation oops ... I'm procrastinating... ?

Thankyou for explaining it in a way I could understand!

 

[Gloi]

I knew TRPM1 was protective against melanoma (the gene that is responsible for the leopard complex), but will have a look into double dilutes, thank you

The melanoma seemed to develop as the horse greyed out. The black from the greying seemed to go into blobs on the pink skin from the double dilute. It had pink skin rather than the black skin most grey's have.

 

[catkin]

My friend has a blue and white chaps registered show pony mare and her blue bits are definitely getting lighter, she looks more like a grey than a coloured although I think in the ring she often really stands out, she has won alot in coloured classes so I think judges do really like her and moves beautifully ?

I think she is 9 now but her dark bits have definitely faded.

I had a blue and white mare who was the same, very dark blue patches that faded with age. Her skin was black under the blue and pink under the white. The blue faded to flea bitten grey which remained all her life (she was 28 when we lost her).

 

[Lois Lame]

The melanoma seemed to develop as the horse greyed out. The black from the greying seemed to go into blobs on the pink skin from the double dilute. It had pink skin rather than the black skin most grey's have.

I'm curious about this double dilute with the grey gene and I wonder what he or she looked like and how the grey gene affected her colour.

 

[Gloi]

I'm curious about this double dilute with the grey gene and I wonder what he or she looked like and how the grey gene affected her colour.

There was no sign of grey at first she looked like a normal perlino with pink skin. As she aged ,as I remember, small black marks started appearing in the skin some of which became larger. Don't know how it would have progresses as she was pts.