Syrian rex x rex mating

[Hekomi]

Ah, Nancy, I had no idea you bred/worked with rex! I thought it wasn't very prolific over here. I did ask on the Rodents Genetics Group for more info, and both Bill from Brookside and Chris Henwood say that it is fine to breed rex to rex.

I wonder how the different perspectives come about? Maybe it was something about some specific lines that caused that? Huh. So strange! I had always heard the same thing, about eyelashes curling under.

[Nancy's Hamsters]

Originally Posted by Hekomi

Ah, Nancy, I had no idea you bred/worked with rex! I thought it wasn't very prolific over here. I did ask on the Rodents Genetics Group for more info, and both Bill from Brookside and Chris Henwood say that it is fine to breed rex to rex.

I wonder how the different perspectives come about? Maybe it was something about some specific lines that caused that? Huh. So strange! I had always heard the same thing, about eyelashes curling under.

Well one CAN breed Wh to Wh and have several litters that are all just Roans too. A "loose" Rex coat(not show quality Kinks) bred to another same quality coat may not produce the issue as well. Also My Mentor didn't re-home her pups until they were 8 weeks to 16 weeks if they were to be petted out and her keeper potential pups were often kept beyond 6 months. So she had the chance to see the issue with the inverted eyelashes better then say an rxrx pup sold before the eyelashes began to hit the eyeball.

Here is my Rex SH girl Hadiya(gotta love them whiskers)
Hadiya-d.JPG

and her 1/2 brother who was a Rxrx LH and was from the oops litter
Tynan-c.JPG

Since my Rex coats were too closely related I had to use pups from them who were carriers for sure with Hadiya, but with Tynan it was and unknown until they were bred to a Hadiya offspring and I got Rex.

[souffle]

Breeding rex to rex means you get all rexes which means that statistically you have a much greater chance of getting pups with eyelash issues. The eyelash thing does seem to carry so 2 rex chances X 2 rex chances means a much greater changed of getting two Rexes with a proneness to inverted eyelashes meeting up. Rexes can also be smaller and the type and size tends to suffer when you breed rex to rex as well as the quality of the fur. It is better to keep outcrossing to normal coats to maintain size and type as well as lessening the chance of the hamsters having inturned eyelashes.

That is not to say you can'y get eyelash problems with rex carrier X rex carrier matings of course. It is just less frequent as not all the pups are rex.

[Sam Zika]

There's some confusion here about how dominant and recessive genes work.

Some dominant genes cause a different phenotype whether they are homozygous or heterozygous. Some of these have negative effects when homozygous. They can be severe defects like anophthalmic white Syrian hamsters (homozygous for white-belly), Campbell's dwarf hamsters homozygous for ruby-eyed mottled, or dogs homozygous for merle. Others cause a phenotype that is not necessary a defect, but people find it unattractive, like homozygous satin Syrian hamsters or homozygous rex rats, which both have very thin fur.

In rats, rex is dominant.
rere = normal fur
Rere = rex
ReRe = double rex; very thin fur

Rex in Syrian hamsters is genetically completely different. It is recessive.
RxRx = normal fur
Rxrx = normal fur
rxrx = rex
There is no "double rex" in Syrians. That terminology doesn't even make sense for a recessive gene.

Crossing two Rere rats has a risk of producing ReRe pups, which will have very thin fur. Crossing two rxrx hamsters will produce only rxrx pups, but they will not be any "more" rex than their parents. The only way they can be at higher risk of inverted eyelashes than their parents is if the parents are related, making the pups inbred. This goes back to the basic tenet of husbandry: More inbreeding equals higher risk of genetic defects.

If you have a rex line, chances are the two rex parents are related, and so yes, the pups would have a greater risk of inverted eyelashes. But it would be because they were inbred, not because both parents were rex.

It seems not all rex lines have this problem; some breeders have worked with rex for many years without seeing it. More info here on a Facebook group: https://www.facebook.com/groups/1575...9081832492289/

[vidasmile]

I‘ve read the whole thread and found Sam Zika‘s question challanging!
Here are my thoughts about this:

1. Genes determine not only fur colour, type or pattern. They do determine far more traits than that. I quess it can be a gene determining the eyelashes. And it can be dominant. Lets name it F.
Lets name the gene for inverted eyelashes with letter f:
f could mean normal eyelashes
F could mean slightly currled eyelashes (or if there is no currled eyelashes in rex, so we could assume that this gene could mean the possibility of inverted eyelashes)

2. The homozygos and heterozygos individuals with dominant genes can get different appearance or as scientists say – phenotype. Saying that hamster with 2 dominant genes in the allele can look diffrent than a hamster with 1 dominant gene in the allele. Fot example with Sg gene. Sgsg (heterozygous silver grey) hamsters have greyish colour with buttermilk colour, while SgSg (homozygous silver greys) have only grey colour.
The same can be with gene for eyelashes:
Genotype Ff (heterozygous) could have normal eyelashes phenotype, but acctually be a carrier of inverted eyelashes.
FF (homozygous) genotipe could determine phenotype with inverted eyelashes.

3. I think inverted eyelashes gene could be linked to rex coat gene. Like we know that yellow gene is linked to sex gene.
So this makes sence. Lets mate two rex whith these genotypes rxrxFf and rxrxFf. We will get 25% pups with inverted eyelashes (rxrxFF), 50% rex who are carrying the possibility of inverted eyelashes (rxrxFf) and 25% rex with no possibility of inverted eyelashes (rxrxff).

4. Linked genes answer the question why some breeders don’t meet the problems with inverted eyelashes breeding rex to rex. If one of the pair is homozygous for both genes rxrxff – the whole litter will be with normal eyelashes.
Assume rxrxff is paired with rxrxFf. We get 75% rex with normal eyelashes and not carrying inverted eyelashes possibility (rxrxff) and 25% will be with normal eyelashes but carrying inverted (rxrxFf).

It is even better if we got lucky and mate two hamsters with rxrxff. Then 100% of litter will be rex with normal eyelashes and not carrying (inverted eyelashes).

Whoala!