Genetic Handbook

Hello, and welcome to my genetic handbook! Here lies all the information you may want to know in order to make educated, professional showcat OCs. It covers everything you'd need to be able to not only create a genetically accurate cat OC, but also to predict the kits a pairing would produce, and even create new genes and breeds of your own to enrich the CFA experience!

## Vocabulary

Here is some vocab you'll need to know to have the deepest understanding possible about the subject going forward.

* Genotype - A cat's genotype is the internal genetic "code" which gives a cat its appearance.
* Phenotype - A cat's phenotype is the physical appearance resulting from its internal genotype. Cats of a very similar phenotype can have very different genotypes, and cats with identical genotypes can vary in phenotype, which can make figuring out a cat's breed or color and pattern difficult.
* Gene - A gene is an individual "piece" of a cat's genotype "code", typically representing one specific trait of the cat's appearance.
* Allele - An allele is a version of a cat's gene. Most genes, especially in pelt patterns and colors, have many alleles which can lead to a myriad of interesting pelt combinations when expressed.
* Are Present - If a gene exists in a cat's genotype, it means it is present in the cat.
* Expression - When a gene is present, and the trait it represents is visible on the cat's coat (or eyes, build, fur texture, etc.), then the gene is being expressed.
* Dominant - A dominant allele is one which, when present, expresses itself on the cat over any other variants of itself in the cat's genotype.
* Recessive - A recessive allele is one which only expresses itself when no dominant alleles of the same gene are present in the cat's genotype. If a dominant allele is present, it gets masked (meaning the allele is still present in the cat's genotype, but is not expressed).
* Codominant - If two or more alleles on a gene are equal (meaning one is not dominant over the other), they are codominant.
* Hybrid - A hybrid is what occurs when codominant alleles of a single gene are present in a cat (Also known as "coat blending" in certain instances; see below)
* Homozygous - A cat is homozygous (dominant or recessive) for a gene if its two alleles are of the same type. Typically this is represented as BB (if dominant) or bb (if recessive) in genotype terms.
* Heterozygous - A cat is heterozygous for a gene if its two alleles are of different types. Typically this is represented as Bb in genotype terms.
* Sire - A male cat; typically used to refer to the father of a litter.
* Dam - A female cat; typically used to refer to the mother of a litter.
* X Chromosome - One of two sex chromosomes; (normally) sires only have one, and dams have two.
* Y Chromosome - One of two sex chromosomes; (normally) sires have one, and dams have none.

# Classic (Real Life) Genes

## Colors

Domestic cats come in two basic colors - black and red. This is the foundation of the expression of all genes and coat types in a cat, pelt-wise.

Black, at its core and unaffected by other genes, is expressed as a deep black color on a cat's coat. This color appears when a cat has at least one copy of the dominant allele of the black color gene (BB, Bb, Bb1).

However, there are 2 other alleles of this color. If a cat has the chocolate allele of black (a recessive allele represented by b; combinations include bb and bb1), then the cat will be a rich dark brown instead. The third allele is cinnamon, which is represented as b1b1, and expressed as a reddish brown which is lighter than its other two alleles, but darker and redder than genetic red.

Because of the nature of the alleles (with black being the most dominant, cinnamon being the least, and chocolate in the middle), this "dominance order" also determines how rare those colors are, with black being the most common and cinnamon the least, especially in the wild.

Conversely, there is red, which has only one allele (red, represented by O/o, strangely enough) and is expressed as any color ranging from blood orange to ginger to lemon yellow, even to caramel (essentially, any color appearing on the orange spectrum).

Red is also a color which, unlike black, cannot be expressed as a solid color - instead, it gets expressed as if it's a mackerel tabby, even if genotypically it's a purebred solid. While breeders have gotten very close to representing red as a pure color thanks to very careful breeding to blur or darken the stripes, it's still not nearly perfect, and its true nature will likely always shine through.

Another thing to note is that red (and, by extension, cream) is sex-linked as a color. It is because of this that tortoiseshells are possible - but only for female cats - and that red cats are disproportionately male. More on that in the tortoiseshell section.

However, these are not *all* the ways that colors can appear. There is also the dilution gene, which takes the colors mentioned before and makes them lighter and duller, as though they were watercolor paints which were diluted with water. It is a recessive gene, meaning a cat with it must have two recessive copies of the gene (dd) to turn dilute; if a cat receives the dominant form of the gene (DD or Dd) from either parent, then the cat will be dense (meaning its fur will be dark and default, not diluted).

The dilution gene, when present in its homozygous recessive form (dd), changes black to blue (grey), chocolate to lilac (slightly-purple pale brown), cinnamon to fawn (an even paler rosy brown), and red to cream (creamy beige). Fawn and cream are very similar phenotypically, so they're easy to mix up if you're not sure of the genotype of the cat. A good rule of thumb is that if a cat looks more yellow or gold than silvery-brown, the cat is cream, not fawn. The differences between the colors are subtle, especially in real life where lighting and other factors can affect how the color is perceived, but with OC designs these differences can be made clearer.

The neat thing about this system is that dilution is separate from the differing color alleles; this means that if you breed a grey (dilute black) and a cinnamon cat (meaning BB/Bb/Bb1dd x b1b1DD/Dd), then you wouldn't necessarily get either color - instead, your kits would be black (or other dense colors, depending on whether the colors were heterozygous or not).

There are also two other known genes which affect a cat's coloration: caramelization, and the much more elusive and debated Barrington brown, which was discovered years ago and is now considered by many to be extinct as a gene. Though the caramelization gene only affects diluted cats and Barrington brown only affects dense cats, they are both modifiers of the base colors which give them a soft browning - ie, if a cat is caramelized, it gains a burnt sienna tint, while the Barrington brown gives the cat a mahogany tint.

# NOTE: ALL TEXT BELOW THE LINE IS PART OF A WIP. THIS GUIDE IS FAR FROM COMPLETE!

## Patterns

### **The Agouti Gene**

tabby (dominant) - aka agouti; instead of being a solid color, the hairs are banded which gives the fur a specific pattern (usually resembling spots, stripes, or similar). the base color is used for the stripes, and the rest of the body is a lighter color - the "tabby color". all tabbies have some kind of M-like marking on their forehead no matter how faint or broken, and most tabbies have very pale fur on their muzzle and around the eyes. usually the neck and underbelly are somewhat paler than the tabby color also

>mackerel (dominant) - the type of tabby most people think of as tabby; stripes are all fairly straight and even bar-like, flowing down the sides from the spine and reminding some of the mackerel fish

>braided - resembles tiger stripes (some stripes resemble candle flames or holes in trees, forming random "bubbles" that flow together); this is a modified mackerel tabby that stems from the the toyger, a wildcat hybrid

>pinstripe - similar to mackerel tabbies, except the stripes are "bumpier" (not as smooth in shape), more tightly packed, and "broken" less often. the stripes themselves are not unlike the "lines" in pinpoint art. this is a modified mackerel tabbies.

>blotched (recessive) - aka classic tabby; instead of having clear "stripes", there are thick bands of color that form swirly markings, specifically a bulky mirrored spiral on each flank

>marbled - blotched tabby, except a lighter semi-metallic color fills the "inside" of the markings, making it resemble a marble cake; typically stems from wildcat hybrid breeds

>spotted (dominant) - spots (can be round, square or "irregular" in shape) cover the coat in a semi-organized pattern along the flanks, with (usually broken) stripes along the face, legs and tail where the spots fade out

>rosetted - a subset of spotted tabbies where the spots resemble those of a leopard (globby "rings" of the base color with a slightly lighter color inside and the normal pale "tabby" color surrounding it); typically stems from wildcat hybrid breeds

>ticked (dominant) - tiny flecks of the base color are spread out into a gradient-like pattern across the back, fading into the paler "tabby" color. this effect resembles sand. most (non-purebred/moggy) ticked tabbies have "residual" stripes on the face, legs and latter half of the tail

smoke (dominant) - "dusts" the pelt with a light "metallic" color; normally lightest at neck, underbelly and sometimes tail and weakest at face and legs. when seen in a tabby (as opposed to a solid color), the smoke color replaces most of the paler "tabby" color on the cat, but leaves the base color for the stripes (turning it into a "silver/golden tabby")

>silver - silvery white; forms silver tabby

>gold - pale golden beige; forms golden tabby

chinchilla (dominant) - smoke, except the metallic effect is much more noticeable/takes up a majority of the pelt

>both smoke colors apply, forming a silver chinchilla and golden chinchilla respectively

## Mosaicism & The Red Color

tortie/torbie (not dominant or recessive) - mosaicism in female cats; when a black-based color (black, brown, russet) on one x chromosome is combined with a red-based color (ginger) on the other, the two colors get scattered around the fur in random bits and pieces, forming a tortie/torbie. tortie is "solid" (solid black-based + red-based), while torbie is "tabby" (tabby black-based x red-based). ginger cannot be solid, so it is tabby by default

>all tabby types apply

calico/caliby (not dominant or recessive) - calico is tortoiseshell with distinct patches and white spotting; caliby is torbie with distinct patches and white spotting

>all tabby types apply

## Albinism

### **Temperature-Sensitive Albinism (Colorpointing)**

point (recessive) - aka temperature-sensitive albinism; the cat is born a pale creamy white, but their extremities (ears, face, legs and tail) get darker over time because they're the coldest areas of the body. body temperature determines how "dark" a point is (ie how much of the base color shows beneath the paler "overlay" color). note: this marking type is temperature sensitive, but it DOES NOT CHANGE OVER TIME. if a cat is raised for the first few months of its life in a very hot environment, they will stay very pale even if they live in the snow the rest of their life, and vice versa

lynx point (recessive) - point, but with tabby instead of solid color; the tabby stripes are "hidden" by the point (meaning they don't show up unless that part of the body is cold enough during kithood), so they don't show anywhere except the parts of the extremities with color

>all tabby types apply

## White Spotting

bicolor (dominant) - a cat is composed primarily of a single color/pattern and white spotting (certain parts are colored white). note that many of the types listed below can be combined to make the cat's pattern more interesting. also note that these marking patterns aren't always set in stone; there can be miscellaneous patches of white or patches of color on a cat's coat even if they otherwise fall into one of these types
note about bicolors/white-spotting: 0% = ww, 1%-50% = Ww, 51%-100% = WW

>locket - whole cat is colored, save for a small white locket on the chest (or other small white spots around the body; typically only one or two)

>mitted - whole cat is colored, save for the paws (which have white "mitts" or "socks" depending on how far up they go)

>tail rings - rare; whole cat is colored, save for one or more rings around the tail

>monocles - rare; whole cat is colored, save for spots around one or both eyes

>tuxedo - whole cat is colored, save for (part of) the face, the chest, the underbelly, the paws and sometimes the tail tip; sometimes will have "buttons" of color along the belly

>hood & cape - whole cat is white, save for a "cape" across the back (normally including the tail) and a "hood" over the head and face (not unlike batman's mask)

>cap & saddle - whole cat is white, save for a "cap" on the head (including ears and top of head, but normally only the tops of the eyes if any eye at all) and a "saddle" on the back (a large colored patch centered around the lower spine/haunches; normally includes the tail)

>van - whole cat is white save for the ears and tail

>white masking - entire cat's body is covered in white, and no base color shows through; when the kit is born, a spot of the original color may appear on the forehead, but it goes away over time. when paired with blue eyes, this gene can cause deafness

>speckled legs - when a cat's paws or legs are white, sometimes they will be "speckled" with the base color. normally this never happens on van or white masked cats, but cats with lower-grade (less) white can sometimes be found w/ these freckles. the speckles may also appear on the tail or face if those areas have white

>banded - rare; irregular white spotting pattern that features a thin "belt" or "band" of white around an otherwise normally-colored cat

>blanket - rare; irregular white spotting pattern that features a thick "blanket" of white wrapping around the entire middle torso from elbow to knee

>skunk stripe - rare; irregular white spotting pattern that features a thick stripe of white going from the scruff down the spine, either striping or engulfing the tail. may also whiten the neck, underbelly, paws or muzzle

>karpati - rare; temperature-based gene that causes the extremities (coldest areas) to become white, while the rest of the cat keeps its base color. somewhat like a reverse point.

>roan - rare; a type of white that "sprinkles" evenly on the pelt, kind of like smoke (seen below). connected to the lykoi breed and genes (sparse fur), but not necessarily the same gene as the fur texture

>brindled - rare; caused when a tortie's red color fails to produce color, so the red parts are white instead

>russian topaz - rare; irregular white spotting, may have unusual patches on the face and paws, and may even spread to cover the front half of the cat (leaving the back half their normal color); connected to the black-eyed gene, but not necessarily the same gene

>finnish - rare; legs, underbelly, tail and part of face are white, and the body has white spots in a pattern resembling a spotted tabby. the main body color is also dusted with white (making it appear paler). the remainder of the face (that isn't marked w/ white) is the normal color, as is the scruff and base of the tail

>moscow - rare; resembles a silver blotched or marbled tabby, except the markings have much starker contrast, are unusual/non-tabby-like, and are caused by the white spotting gene instead of a tabby gene

other notes:

scars - when a cat is injured, and it leaves a scar, any fur that grows over the scarred area will be white. this is because the injury damages the skin enough to prevent it from producing any color like it's supposed to, so the fur that grows from it will be 'without color' (ie white)

>technically, most white spotting on cats is actually just leftover scar tissue from the colored skin of the kitten cracking while it's an embryo, although the process doesn't hurt

## Body Types

cobby - flat face, compact stocky build (exotic shorthair, persian, manx)

semi-cobby - short face, burly build (british shorthair, american wirehair, scottish fold)

semi-foreign - average face and build, an even mix of both cobby and foreign (egyptian mau, havana brown, snowshoe)

foreign - defined face, lithe build (abyssinian, russian blue, turkish angora)

oriental - long face, tall slender build (modern siamese, balinese, cornish rex)

substantial - large and bulky face and build (maine coon, norwegian forest cat, turkish van)

## Fur Types & Lengths

short - short fur everywhere

medium - long fur in cheeks, neck, underbelly, tail and haunches; short fur elsewhere

long - long fur everywhere

furless (sphynx) - cat appears to have no fur at all (but usually just has a very thin, invisible coat of underhairs)

sparse fur (lykoi) - fur is very thin and not tightly packed, giving it a sparse and "werewolf-like" look

wiry fur (wirehair) - the cat's fur is thick, coarse and appears "gnarled" (not unlike a carpet); normally short (american wirehair), but may also be long

curly fur (laperm) - the cat's fur forms tight curls instead of being straight; normally long (laperm), but can also be medium/short (selkirk)

wavy fur (rex) - the cat's fur is soft and forms ripples close to the skin; can appear sleek or fluffy, depending on breed; normally short, but may also be long

## Eye Colors

copper - bronze to muddy crimson

orange - pale dusk orange to fiery orange to dark orange

amber - muddy mix of orange and yellow

yellow - pale sunny yellow to brilliant gold to dark honey yellow

hazel - olive green to chestnut brown (usually a muddy mix of green and yellow)

green - pale minty green to sea green to lime green to emerald green to dark pine green

turquoise - pale cyan to normal turquoise to teal

blue - pale icy blue to bright sky blue to intense royal blue

indigo - deep rich blue color w/ purple tint

black - very very dark night-sky blue; comes from russian topaz. sometimes has red pupils

## Miscellaneous Traits

ear shape:

>curled ears (dominant; AcAc or Acac) - ears curl back (american curl)

>folded ears (dominant; Sfsf only, SfSf is lethal) - ears fold forward like the top of an envelope (scottish fold)

eyes:

>crossed eyes - pupils are "crossed" inwardly instead of looking straight ahead (certain thai siamese)

tail:

>short tail (manx) - tail is naturally shorter than usual. comes in 3 main forms; half-length, stub, and tailless

>ringtail - tail is limper than usual and curls loosely over the back

>corkscrew tail - tail is more tightly curled over the back into a spiral pattern

>bobbed tail - like a pug, the tail is short and corkscrewed (tightly curled)

>kinked tail - tail is "kinked" or crooked/bent naturally at at least one point, normally at the tip (but can also be further up the tail). whether from injury or genetics, a kinked tail is usually much stiffer than a normal one because of the bone structure, which may get in the way of communication with clanmates

legs:

>short legs (munchkin) - dwarfism in cats. normally the only effect is making the legs freakishly short (leaving the rest of the body intact like an adult cat), but it can also affect the facial structure too (giving a "grumpy" face; see also tardar sauce)

paws:

>extra toes (polydactyl) - one or more paws have more toes than usual (can be as little as a dewclaw on a hind leg or a 6th toe on the front paw, or as extreme as 8 toes on each paw). normally benign, but with too many toes (ie pattyfoot) it may make walking or maneuvering with the paws difficult

# Original (CFARP-Specific) Genes

merle (dominant) (derived from dogs) - technically a hypothetical/nonexistent gene, merle is the patching of dense color onto an otherwise dilute cat (ie black patches on grey), presumably in the same vein as tortoiseshells/calicos; however, merle only affects black and not red

## Guide to Genotype Writing

Note: Because of chromosomes, male kittens' base colors are determined by their mother alone, and female kits are affected by both their mother and father, taking a copy of the color gene from each.

XX or XyXy = Homozygous dominant
xx or Xyxy = Heterozygous
xx or xyxy = Homozygous recessive

## Classic Genes

base color:
BB > Bb = Black
bb > bb1 = Chocolate
b1 = Cinnamon

dilution:
DD > Dd = Dense
dd = Dilute

dense modifier (mahogany):
BaBa > Baba = Mahogany
baba = Not mahogany

dilution modifier (caramel):
DmDm > Dmdm = Caramel
dmdm = Not caramel

red (males):
XoY = Not red
XOY = Red

red (females):
XoXo = Not red
XOXo = Tortoiseshell
XOXO = Red

tabby:
AA > Aa = Tabby
aa = Solid

Tabby Types:
McMc > Mcmc = Mackerel
mcmc = Classic
SpSp > Spsp = Spotted (overrides mackerel + classic)
spsp = Not spotted
TaTa > Tata = Ticked (overrides mackerel + classic)
tata = Not ticked

Smoke:
II > Ii = Silver/golden smoke
ii = Not silver/golden smoke

Tipped:
WbWb > Wbwb = Tipped gold/silver
wbwb = Not tipped gold/silver

"Norwegian Forest Cat" Amber Color:
EE > Ee = Not amber
ee = Amber

Colorpointing:
CC > Ccs > Ccb = Not pointed
cscs = Colorpointed
cscb = Mink
cbcb = Sepia

White Spotting:
WW = 50%-100% white
Ww = 0%-50% white
ww = No white

Fur Length:
LL > Ll = Shorthaired
ll = Longhaired

"Cornish Rex" fur:
RR > Rr = Cornish Rex fur
rr = Normal fur

"Selkirk Rex" fur + "Devon Rex" fur + "Sphynx" hair:
ReRe > Rere > Rehr = Normal fur
SReSRe > SReRe = Selkirk Rex fur
rere = Devon Rex fur
hrhr = Hairless

"laperm" curly fur:
LpLp > Lplp = LaPerm fur
lplp = Normal fur

wirehair:
WhWh > Whwh = Wirehair
whwh = Normal fur

lykoi:
LyLy > Lyly = Normal fur
lyly = Lykoi fur

curled ears:
AcAc > Acac = Curled ears (American Curl)
acac = Normal ears

folded ears:
SfSf > Sfsf = Folded Ears (Scottish Fold)
sfsf = Normal ears

indigo eyes:
OaOa = Fatal
Oaoa = "Indigo" blue eyes (Ojos Azules)
oaoa = Normal eyes

short tail:
MM = Fatal
Mm = Short tail (Manx)
mm = Normal tail

bobbed tail:
JbJb > Jbjb = Normal tail
jbjb = Bobbed tail

short legs:
MkMk = Fatal
Mkmk = Short legs (Munchkin)
mkmk = Normal legs

extra toes:
PdPd > Pdpd = Extra toes (polydactyl)
pdpd = Normal toes

## Original Genes

Merle:
MmMm > Mmmm = Merle
mmmm = Not merle

Credits:

Special thanks to Messybeast for allowing me to write this guide so comprehensively. Please go check it out if you'd like to learn even more on the topic of feline genetics, breed standards and history, caring for a cat, and even more - it's a fantastic resource unlike any other I've come across.

Also, big shoutout to the cat coat calculator from Sparrow's Garden for assisting me in compiling and determining the genotype representations of each gene, as well as for being an incredibly useful tool for figuring out what kits can come from pairings. It's invaluable as a resource compared to manual prediction. In fact, the entire genetics section of the site is great for learning about the subject as well.