# Health and genetics



## GitaBooks (Aug 31, 2015)

I am studying animal genetics and have become interested in the relationship between color and health in animals. For example, a white cat with blue eyes is more prone to deafness, or a dilute dog is more prone to hair loss. There is a lot of useful information on here, but I was wondering if anyone could add to the list of possible weaknesses or lethal genes in mouse colors? I have a pretty good list down, but I'm no expert on this.

Keeping track of what health issues may crop up in varieties/breeds helps people to avoid selecting for that issue or ending up with genetically weak animals.

Thank you for the help. I hope this helps other people as well. : )

Albino: albino mammals have been shown to suffer from sight problems and sensitivity to bright lights as well as an increase in immune system problems and cancer. Any animal with red eyes may have problems with vision, including Argente, Champagne, Himalayan, Lilac/Dove, Siamese, silver, Recessive Yellow Pink Eyed, Pink-eyed and Ruby-eyed Whites, and Lavender. Some Cove Point Siamese may also have rub eyes.
American Fold: Skeleton problems
Brindle: increased risk of obesity and shortened lifespan, though selective breeding may help with this
Brindled: lethal in males (unless given copper in their first week of life) and in homozygous form
Dutch: said to be smaller and more flighty then most other mice varities
Gremlin: May or may not be connected with limb deformities 
Hairless: Prone to temperature control issues, scratches, and possibly other issues
Lethal Yellow: lethal in homozygous. Heterozygous mice are prone to tumors, weight problems and diabetes
Longhair (lgh): Possible skin lesion issues in homozygous
Manx: homozygous Recessive Manx may lead to spinal issues that cause weakness in the back-legs; heterozygous may have a kinked tail
Merle: likely related to Roan
Nude: Usually die before weaning. Different then hairless
Piebald Lethal: A lethal gene
Rex: May get weepy eyes more easily
Rhino Hairless: Prone to temperature control issues, scratches, and unnaturally wrinkly skin
Roan: Homozygous lethal
Rump White (Rw): Lethal in homozygous
Satin: Linked to an immune disorder that makes fighting viruses and tumors harder
Tailess: Too many varieties to specify, but may cause issues with temperature control and balance
Tri-color/Calico: Waltzer mice, or neurological issues that cause deafness and walking in circles
Variegated/Dominant Spotting (W/w): Lethal in doubled form

Let me know if I made any mistakes. : )


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## Lilly (Nov 21, 2015)

Just a few things that I can think of

American Fold: Skeleton problems
*While they have been listed as this by the AFRMA, a breeder has had her line going for 20 years or so without any of those issues being present at all according to her. I think it was just assumed that they would have issues without real knowledge*

Brindled: lethal in males (unless given copper in their first week of life) and in homozygous form
*In mice this is called brindle too, but referred to as sex-linked brindle just to tell it apart if needed. Also a section from Hiiret.fi that might interest you:*
Brindle appeared as a spontaneous mutation in 1953. It is a rather difficult variety to breed for several reasons even though it's dominant. First of all, it is sex related so that only females show the distinctive pattern. Males resemble more siamese mice with curly whiskers. Brindle is also usually lethal for males. If some brindle males survive and are fertile, mated with a brindle female all mice in the litter resemble the father. Another thing is a neurological condition present in the brindles, some of them tend to wobble when walking and shake. When lifted from the tail, the hind legs of these brindle mice also clasp together instead of spreading out. Some brindles lose control of their hind legs as they age, but this is fortunately rather rare. I know this information has been labeled nonsense by some fanciers, but all I can say is: if your brindles haven't been affected at all, consider yourself lucky!

Dutch: said to be smaller and more flighty then most other mice varities
*Smaller and flighty tends to be more about breeding than about the genetics, black selfs are smaller than pew for example, because with pew you can focus on size/type but with marked/patterned varieties you have to worry about the marking or pattern which slows down size/type development. Flighty would also be down to how much they're handled or how established the lines are.

I would be interested if it is actually to do with the genes as oppose to breeding because I find this kind of stuff fascinating too*

Roan: Homozygous lethal
*This one confused me so I asked Laigaie, apparently there used to be a dominant form present in California that had issues, but the recessive gene now bred in the fancy is not homozygous lethal*

Tri-color/Calico: Waltzer mice, or neurological issues that cause deafness and walking in circles
*There are no calico mice if you are thinking in the same sense as cats where it is sex linked and you get red/black/white markings. Mice cannot normally have red and black together. Tri-color is essentially the splashed gene + pied and as far as I know splashed does not have health issues specifically.*


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## Laigaie (Mar 7, 2011)

Before I start commenting on individual things, I'd like to take umbrage with the phrasing here. Many of these aren't weaknesses or problems, but instead quirks that are generally irrelevant to the health of the mice in question. That's not to say that they're irrelevant to breeding the variety, especially when we're talking about lethal genes or obesity, but a lot of this...it's just not accurate to the experiences of people in the hobby. For specifics:

Any animal with lighter eyes is going to have slightly more sensitive eyes. The way you've phrased it, it sounds like you're saying they're virtually blind. In reality, their acuity is slightly lower, and they're more light-sensitive. Like many of us. >.> Also, albinism isn't linked with any immune or cancer problems, though specific lab strains that happen to be albino have been developed for those things, along with others.

I have not heard from breeders or seen lab reports indicating that Avy gives a shorter lifespan, and indeed obese and/or diabetic mice often live full lives. I had an incredibly obese Ay doe die this past week who'd've been three in October. Sweet sweet girl, my Butters.

Most gremlins are one-off deformities, rather than being a specific lab-identified gene. Technically speaking, almost any change in positioning/size/shape of anything on the head qualifies as a "skeletal deformity" as they're usually caused by changes in skull shape. That doesn't make them health problems.

I'm also not familiar with Ay mice being more prone to tumors, though certainly diabetes and obesity are present just as in Avy mice. Ay does have been shown in labs to be less likely to have Ay/* embryos implant in their uteruses than non-Ay does are. This is assumed by the researchers to be related to the lethality of the gene, where a non-Ay endometrial lining is more likely to accept an embryo with a copy of Ay, while Ay/Ay embryos don't implant in either, and Ay/* embryos are less likely to implant properly in Ay endometrial lining. I wasn't able to understand the mechanism of action, but it leads to an even further reduced number of Ay pups in Ay litters when the doe is Ay. Using an Ay buck on a non-Ay doe is the recommended way of avoiding this.

Most breeders assume the fancy has go rather than lgh, in part because there are no reports of skin issues in long-haired mice in the fancy. At a bare minimum, we all seem to have the same gene (whatever it is) because nobody has bred two long-haired mice and produced only short-haired pups.

Recessive manx is to my knowledge only in Aus. The rest of the world has dominant manx, which also can result in a too-short spine or hip deformities. There's nothing in the manx genes that tells it how far is too far when getting rid of tail.

Merle is ro^un, a recessive gene that can be expressed as either merle or roan (when there are no solid patches). It has no known health issues, though there are lines in the US both with and without imperforate vaginas.

Nude and rhino hairless are not thought to be present in the fancy, though rhino has been present on the US east coast in the past.

Can you tell us which gene is "piebald lethal"? I'm not familiar with such a gene in the fancy, unless this is another name for variegated.

I have bred many generations of rex/texel (and known folks breeding many generations of fuzzy, its curlier cousin) and never seen congenital eye problems. This is an unfounded fear based on zero facts, but often reported by those who've never bred them.

I'm not familiar with any health problems associated with satin, either, unless one considers clear (but perfectly healthy and usable) teeth to be a "problem". Can you cite a source for that one?

Tricolor as currently known in the fancy is completely unrelated to Waltzing mice. It's the splashed gene, the pied gene, and some c-dilutes in combination, selectively bred. None induce health problems aside from the eye acuity/sensitivity issues in red-eyed c-dilutes as mentioned above.


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## pauly (Feb 21, 2013)

You raise some very good points Laigaie, my Siamese are prone to developing tumours, yet probably the most successful fancier in England at present, doesn't have them in hers. I think the individual line has as much bearing as the variety.

My Creams when I first got them, over three years ago now, were racked by asthma, it was a battle to find a healthy one to breed to, a disaster really. After a lot of outcrossing to Himmi's & a lot of culling of some good looking mice, the line is pretty healthy.

My Agoutis never seem to suffer from anything though.


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## Amtma Mousery (Jan 29, 2015)

Interesting post! I was not aware of a lot of this information!

I must support Lilly's statement that there is at least a non-lethal homozygous Roan gene in the United States. My Roan stock average 9-11 pups per litter. Additionally, I am unsure if this is affiliated with the recent foundation of my stock, but they seem to be overall smaller then other variations, resembling much like the common physique of Blacks.

Sorry to hear about the genetic vulnerability of tumors in your Siamese mice. I am lucky that I do not have that trait. It must be a challenge to resolve it since you would probably have to raise the stock to fully matured ages to identify carriers of the negative gene. My immunity weakness in my Siamese resemble your Creams, as they suffered from a Myco outbreak a few generations ago.

I have noticed a pattern in my stock of mice (Siamese, Roan, Black) that smaller ears often result in heavier/stockier physiques, where as larger ears often result in lighter/thinner physique.


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