Frizzling gene

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Frizzling gene

Postby julieszoo » 05 Jan 2011, 22:38

Could someone please explain how this gene works. I understood it was dominant, and that the birds with the correct feathering are the heterozygous ones? I commented on a post in the sales section where someone mentioned frizzle being carried as I could not see how this could be the case, and the reply has confused me. Was hoping one of you genetics whizzes could help please [-o<
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Re: Frizzling gene

Postby Hen-Gen » 10 Jan 2011, 17:33

OK
The frizzling gene is a single gene dominant.
f+f+ is normal feathered
Ff+ is frizzled
FF is super frizzled
A super frizzled bird is partially bald and the growing feathers are so brittle that they repeatedly break off. For this reason the usual mating is Normal x Frizzle because this gives 50% of each with no Super Frizzles.

However this simple pattern of inheritance is complicated by the existance of another gene called the frizzle modifier gene. In this case the mutation is recessive so:-
Fm+Fm+ is normal
Fm+fm is normal but a carrier
fmfm is modified
The frizzle modified bird prevents the frizzled bird growing frizzled feathers so it looks completely, or nearly completely, normal. So in this case a bird can carry the frizzle gene but not be frizzled. But if this bird is then mated to a normal bird that does not have the frizzle modifier gene then half the offspring will come frizzled which gives the impression that the frizzle gene itself has been carried as a recessive even though this is not the case.
Not an easy one to get your head around and in the majority of cases where a frizzled bird crops up from two normals then its due to a mismating. But nevertheless in some cases this other explanation is correct.
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Re: Frizzling gene

Postby andoy » 10 Jan 2011, 19:23

=D>
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Re: Frizzling gene

Postby julieszoo » 11 Jan 2011, 18:33

Many thanks Hen-Gen that is very helpful :thumbright: I guess that if you breed frizzle feathered birds you would try hard to eliminate the frizzle modifier gene as it is effectively reducing the number of visual frizzles that can be bred?
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Re: Frizzling gene

Postby andoy » 11 Jan 2011, 20:29

yes, frizzle modifier is not exactly helpful in a breeding program for Frizzle. However, in theory if you develop a strain that is homozygous for both Frizzle and frizzle modifier genes, then you have a Frizzle that breeds true. I.e. Breed individuals from this strain together and get 100% Frizzled offspring. However, this would be quite difficult to develop because of the nature of frizzle modifier and detecting/testing for it.
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Re: Frizzling gene

Postby Hen-Gen » 12 Jan 2011, 17:33

I've asked that as a question elsewhere, andoy, because I would be interested to know whether anyone has tested out that theory.
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Re: Frizzling gene

Postby araucana » 12 Jan 2011, 17:46

Andy - you know I'm thick, you'll have to explain in diagrams for me at the scot nat.. I can't get my head around frizzle at all - and I'm going to have to understand as I'm going to have 2 chamois poland straight feather hens, 1 frizzle hen, and a straight feathered cock!!! :grin:
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Re: Frizzling gene

Postby andoy » 12 Jan 2011, 18:18

hi Hen-Gen :wave: yes I'm going by the genetic books and a few papers I've read. I know not how extensive they have tested. I'll ask a friend of mine who works on genetic study and has access to more in-depth scientific papers/studies. I would have thought some members/breeders in Frizzle society would have an interest in this subject as it would mean Frizzle breed could breed true. Though, quite a few lines need to be set to make it viable for the breed. I have no interest in the frizzle gene at all and no facility/space to try it out myself even if I did.

Hutt suggests that frizzle modifier (fm) is common enough in other breeds (outside of Frizzle breed). I image Frizzle breeders select it out inadvertently.

Arucana:
--> Well homozygous for the recessive frizzle modifier (fm) (2 copies of fm) has effect of nullifying one dose of Frizzle.
--> A homozygous Frizzle is a Frazzle (i.e. 2 doses/copies of Frizzle is a Frazzle).
--> Therefore a Frazzle that is also homozygous to frizzle modifier (fm), should look like a Frizzle (heterozygous or single copy of Frizzle).

will explain over sushi rolling sessions and a few pints of beer ;)
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