Tortie or chimera?

[Willowy]

A local cat rescue just posted this on Facebook. She is a female, so she could be a funny tortie, but I thought the placement of her markings seem odd, maybe a chimera? Just wondering what everyone else thought.

I don't know anything else about her and I can't get more pictures.

 

[Willowy]

 

[lutece]

Torties can have any combination of red and black patches... some have lots of red and some have lots of black. Both processes (formation of a chimera, and x-inactivation) happen very early in development, and the patching patterns tend to be similar... I don't think you can distinguish a chimera from a normal tortie based on its patching pattern alone.

Another possibility, however, is a somatic mutation which can form later in fetal development. This can be the cause of a single black patch on a red cat.

 

[GreyLady]

Looks like a spotted Tabby to me. Cute!

 

[StefanZ]

Looks like a spotted Tabby to me. Cute!

The behind clearly hints a spotted tabby. But the body is clearly a mackerel / body mackerel. If she is a chimera, so this is it, not necessarily the blackish spots...

Anyway, a little of a riddle to ponder ower. Unless you just buy her as she is, and give her all the love she deserves, without any internal doubts nor reservations...

 

[lutece]

The behind clearly hints a spotted tabby. But the body is clearly a mackerel / body mackerel.

It's normal for mackerel tabbies to have some of their stripes broken up into spots... we often see intermediate examples between mackerel and spotted.

 

[The Goodbye Bird]

The behind clearly hints a spotted tabby. But the body is clearly a mackerel / body mackerel. If she is a chimera, so this is it, not necessarily the blackish spots...

Here would be my bet (but to actually bet, I would need odds, because chimeras are rare, but assuming the odds reflected the frequency of chimera versus torties, here would be my bet):

Seems like the cat whose butt this is was a tortie and the cat whose front half this is was not. There is another patch on the base of the tail, and another on the back.

So I'm actually admitting this isn't very likely, especially seeing the spots recede into stripes again on the haunch. It's just odd, especially considering two of those black marks are right where the pattern changes and confusingly one of them seems to be trying to replace a stripe.

 

[lutece]

Chimeras are formed very early in development, before any body structure has been formed. They typically have random patching all over the body similar to a tortoiseshell.

 

[The Goodbye Bird]

Chimeras are formed very early in development, before any body structure has been formed. They typically have random patching all over the body similar to a tortoiseshell.

The times when there's some kind of clear barrier, however rare or common, are the times when you can really spot one.

That's why I would give the OP's cat a higher-than-normal chance to be a chimera, because of that belly stripe and the way it looks, but I admit that this still means it's overall more likely just a calico.

 

[lutece]

"Split face" as in your picture doesn't indicate that the cat is a chimera. It is seen in normal tortoiseshell cats.

CAT CHIMERAS (MALE AND FEMALE)

Because patch patterns in chimeras are similar to tortoiseshell cats, it is possible to see a "split face" in a chimera, but probably not any more likely than split face in any tortoiseshell cat. Chimeras are formed early in development and the cells tend to mix together.

A mutation that affects just one patch of a cat is thought to be more likely to be a somatic mutation. Black patches on an orange cat seem to pop up fairly often as somatic mutations, oddly enough... I have seen several of them posted on genetics groups.

 

[The Goodbye Bird]

Because patch patterns in chimeras are similar to tortoiseshell cats, it is possible to see a "split face" in a chimera, but probably not any more likely than split face in any tortoiseshell cat.

Well I was wrong then, but this is due to bad info.

Facts about Chimera Cats

This is in addition to human chimeras often being split down the body.

Understanding Genetics

I always trusted sources that said split-faces weren't just regular torties because I didn't think a regular tortie could generate a blue-eyed cat. I have heard orange cats can be blue-eyed (but I haven't seen one) but if you look at these split-faces, the blue eye is always on the black side.

Also I would expect somatic mutations (that start from a single cell) to be both singular and usually roughly circular.

 

[lutece]

Also I would expect somatic mutations (that start from a single cell) to be both singular and usually roughly circular.

A somatic mutation can happen at any time in development. If it happens very early, you would expect the patches to be distributed through the whole body like a tortie. However, if it happens later in development after the body shape begins to form, it might affect a leg, tail, or patch on the body. Since cells move around during early development, it might cause multiple patches.

A good example of a somatic mutation would be a black patch on a blue kitten out of two blue parents. This cannot be a chimera, as that would require a merge of a blue kitten and a black kitten (impossible from blue parents).

Another example of probable somatic mutation on another group that I recently saw was a lilac kitten with a blue leg, out of two lilac parents. This cannot be a chimera, as that would require a merge of a lilac kitten and a blue kitten (impossible from lilac parents).

 

[lutece]

I always trusted sources that said split-faces weren't just regular torties because I didn't think a regular tortie could generate a blue-eyed cat. I have heard orange cats can be blue-eyed (but I haven't seen one) but if you look at these split-faces, the blue eye is always on the black side.

Actually one of the most famous examples of split faced cats, "Venus the two-faced cat," had the blue eye on the orange side. Most split faced tortoiseshell cats don't have odd eye color, but we see a lot of pictures of the cats that do (like Venus), because the cats become famous and people post pictures of the same cats over and over. It's not clear what caused the blue eyes in these few examples, but it's not chimerism. Chimerism just mixes two kittens together but it wouldn't explain blue eyes on a non white cat. It's possible that these particular cats have a dominant blue eyes gene in addition to being tortoiseshell.

http://[URL]https://www.nationalgeo...venus-two-faced-cat-genetics-animals-science/

[/URL]

 

[The Goodbye Bird]

but we see a lot of pictures of the cats that do (like Venus), because the cats become famous and people post pictures of the same cats over and over.

I've seen a couple different cats with the blue eye on the black side.

One of them is longer hair on the orange side. Something is clearly going on. Maybe it's neither tortie nor chimera. Even your source says the longer hair on one part is a giveaway, but why the blue eye? Clearly the blue eye is related somehow to the split.

And why does this cat on the left have two blue eyes? He shouldn't. Both cats he is are black cats (one is just dilute). I really doubt that such little white spotting is causing that, however...

...isn't it interesting that the distinct chin-wipe, which favours one side, is seen in two separate instances?

And he transmits the chin-wipe to an offspring.

Wild sort of shot in the dark, but the chin wipe could be related to the reason we see the split and related to the blue eye, or eyes. Even wilder stab... What if that particular white spotting causes the embryonic cat head to rift and sometimes, but not always, gobble up part of another embryo?

 

[lutece]

This is in addition to human chimeras often being split down the body.

Human chimeras more typically have a pattern known as Blaschko's lines, which is the same pattern seen in humans with x-linked skin disorders. Basically this is the pattern that a human tortoiseshell would have, if we had an X-linked color gene. I remember learning this in human genetics class!

On a CSI episode, why did the chimera have swirl patterns on his skin? - The Tech Interactive

genetics.thetech.org

 

[lutece]

Clearly the blue eye is related somehow to the split.

I think it's most likely to be coincidence. There are millions and millions of tortoiseshell cats out there. The ones that happen to have odd eyes just happen to get a LOT more media attention.

It's possible, however, that tortoiseshell cats with a dominant blue eye gene might be more likely to have a split face than other tortoiseshell cats. Dominant blue eye mutations are a type of white spotting gene, and we know that white spotting interacts with tortoiseshell patching in some way, which makes calico patches bigger and less brindled.

But I think it's extremely unlikely that it's related to chimerism. Chimerism just gives you a blend of two cats.

And why does this cat on the left have two blue eyes? He shouldn't. Both cats he is are black cats (one is just dilute). I really doubt that such little white spotting is causing that, however...

That cat looks like he has a dominant blue eye gene.

 

[lutece]

I knew I'd seen the blue / black cat before... his name is Narnia, and he is not a chimera -- apparently he was DNA tested and his cells all come from the same cat. His coloring may be due to a somatic mutation. He is probably a black cat carrying dilute, which would explain his blue and black kittens.

"People" is not my favorite news source, but here you are:

Cat Dad with Handsome Two-Toned Face Fathers Two Kittens, One for Each Side of His Head

Narnia might look like a chimera cat, but what caused his striking two-toned face is still a mystery

people.com

 

[Willowy]

Since we're talking about split faces now, here's another kitty from the same rescue :