Talk:Dog coat genetics

Shedding Gene
Much of this section seems to constitute original research. The bold statements below are not supported by the cited source Hayward et al 2016.

The alleles on the melanocortin 5 receptor gene (MC5R) determine whether an animal will have '''neotenous retention of a puppy-like coat type. The locus has not been assigned a common name or letter, but has been called''' the shedding gene or single coat gene. There are two known alleles that occur at this locus:

• The mutant allele (reduced shedding, single coat or minimal undercoat, reduced length)

• The wildtype allele (normal shedding, double coat, normal length) The mutant allele is incomplete dominant. With respect to coat texture, shedding, follicle density and number of secondary hairs per follicle, heterozygotes closely resemble animals homozygous for the mutant allele, with minor differences. [Follicle density and the number of secondary hairs per follicle is not addressed in the source.] With respect to coat length and the prominence of fringing and furnishings, the relationship between the two alleles is more complex and dependent on the alleles present at the L and W loci: [Fringed coats are not described in the source.]

• In short-haired dogs (L/- w/w), this gene causes the smooth coat type that is common in hounds and pointers [article refers to Pugs and Boxers]. '''Coat length is significantly reduced in animals homozygous for the smooth-coat allele, and of intermediate length in heterozygotes. Heterozygosity for long coat (L/l) dulls the effect on coat length. Typically, the undercoat is completely absent.''' Very few breeds (e.g., Chihuahua) have both smooth and non-smooth coat types. [This last statement might be supportable, but not by this source.]

• In long-haired dogs (l/l w/w), '''this gene causes fringed coats (e.g., Saluki, long-haired pointers). Coat length is reduced on the body, but lengthened on the feathering. Fringed coats may have an unbristled undercoat. An overall long single coat (e.g., Papillon, Japanese Chin) requires additional lengthening modifier genes.''' [article refers to Cocker Spaniels]

'''• In wire-haired dogs (L/- W/-), this gene causes short-wire coats (e.g., Border Terrier, Wire-haired Dachshund, German Wirehaired Pointer) only when homozygous, and has no effect on length when heterozygous. Short-wire coats may have a bristled undercoat.

'''• In shaggy-haired dogs (l/l W/-), this gene causes a soft single coat (e.g., Coton de Tulear, Soft Coated Wheaten Terrier, Dachshunds of mixed longhair/wirehair parentage) which varies by breed from cottony to silky. The minimal undercoat of fringed and short-wire coats originates from a different subset of secondary hairs, and is lost when a dog has the alleles for both long and wire hair.'''

• In dogs with long curly coats with furnishings (l/l W/- R/R), this gene causes a single long curly coat with furnishings that will not cord (e.g., most Poodles), as proper formation of cords requires a double coat.

Remaining influences of length (e.g., setter vs Cocker Spaniel), texture (e.g., setter vs mountain dog vs spitz or Bearded Collie vs Old English Sheepdog) and abundance of undercoat (e.g., Labrador Retriever vs Keeshond) are likely polygenic.

I suggest the following:

''A mutation in the MC5R gene, which is expressed in the skin in dogs, is responsible for reduced shedding in some dogs. Dog breeds that shed the most, like the Akita and Malamute, tended to have the normal MC5R whereas breeds that shed less, like the Pug and Cocker Spaniel, usually have the MC5R mutation. Dogs with the furnishings gene, which is responsible for wire-hair, shaggy, and poodle-like coats, shed the least.

The MC5R mutation also distinguished smooth-coated dogs, such as Greyhounds, from short-haired dogs like the Akita or Corgi.''

I'm reluctant to say more about the significance of Alaskan Malamute vs. Cocker Spaniel.

Somatic Mutations and Chimera
It would be nice to add information about Somatic Mutations and Chimera as they account for some of the oddities that affect dog coat formation. "A somatic mutation is a mutation that occurs in the body cells after the embryo has begun to form. Cells are divided into two categories - germline cells (i.e. gametes - sperm and eggs) and somatic cells (all other body cells). When a mutation occurs at the point of conception (when the first cell begins to replicate) then this mutation may enter the germline and so be passed on to future generations, but after this point the two types of cell replicate separately and any mutations occuring in the somatic cells will only be passed on to the descendents of those cells and will not be passed to the next generation. This is because only the information carried in the gametes will go on to form a new individual (of course, mutations may well happen in the gametes too during the individual's lifetime, and these mutations will be passed on)." Jwlee17 (talk) 22:55, 30 March 2022 (UTC)

Breeds that carry dilution
More information can be added under the topic, "D (dilute) locus", which is under "Genes associated with coat color". Specifically, information about the breeds that carry (or have been reported to carry) dilution can be added. For example, dilution can occur in almost any breed, where blue gene is the most common. Also, there are some breeds that come in dilute but with no specific color, such as the Weimaraner or the Slovakian Pointer. Jwlee17 (talk) 23:35, 30 March 2022 (UTC)

Wild-Type Agouti (a^w) genes in Border Collies
I have a quick question regarding the "A (agouti) locus" section under pigment type. Would it be okay to add a short section on the relation between A (agouti) locus genes and Border Collies? This is because Border Collies is one of the few breeds that lack agouti patterning, and only have sable and tan points. However, many border collies still test to have agouti genes. Jwlee17 (talk) 00:02, 31 March 2022 (UTC)

variation on merle allele
There are other new discovery on M locus and it would be useful to add the supplementary category on "M(merle) Locus" part. Since the original section only talk about just one allele M, but there are some variation on the one allele and derive a number of new alleles, which will lead to the other production of pigment. Jerrrrmm (talk) 20:00, 31 March 2022 (UTC)

Cryptic merle (Mc and Mc+)
One of the variation of M allele is Mc and Mc+. Although just one copy of Mc is not long enough to make visible change on coats, the combination of Mc or more than two copies of Mc would lead to odd shade of black/liver. Jerrrrmm (talk) 20:00, 31 March 2022 (UTC)

Atypical merle (Ma and Ma+)
Another type of variation of M allele is Ma and Ma+. This kinds of allele would lead to visibly merle-patterned dog if there are two copies of Ma. It is important to be supplement because if the dog with atypical merle bred to dog with any longer merle allele, the double merle health problems might occur. Jerrrrmm (talk) 20:00, 31 March 2022 (UTC)

Long Hair
There can be expand more on the section "other related genes". There are many genes and alleles that cause long hair in dogs, but most of these genes are recessive. This means that longhaired hybrid breeds usually have to have two longhair or longhair carrier parents, and the gene can also be passed on for many generations without being expressed. Jerrrrmm (talk) 20:00, 31 March 2022 (UTC)

Wire Hair
There are lots of variation of allele would affect the dog's hair. The allele that causes bristles is actually dominant. Dogs with both the longhair and line coat genes will be "coarse," which means longer line coats of fur. Examples of such coats include the Korthals Griffon, and possibly the Irish Wolfhound. Jerrrrmm (talk) 20:00, 31 March 2022 (UTC)

Nose colours
The most common colour of dog nose is black. However, a number of genes can affect nose colour. It is interested to know the genes affection on dog nose coat. Jerrrrmm (talk) 20:00, 31 March 2022 (UTC)[article refers to Dr Sheila M. Schmutz]
 * Liver (bb) dogs and dilute liver (isabella, dd) have noses ranging from deep brown to pink. Liver pigment does not seem to be retained in the nose as easily as black pigment, so many high-white liver dogs have completely pink noses. It is genetically impossible for a liver dog to have a black or blue nose.Blue (dd) dogs have a nose that ranges from light grey to almost black.

Jerrrrmm (talk) 20:00, 31 March 2022 (UTC)[article refers to Dr Sheila M. Schmutz]
 * A blue dog nose is genetically impossible. But greyhounds without the blue dilution gene are sometimes found. Therefore, a dog that appears to be "blue" may have a black nose and black eyes because it is actually a black dog with the gray gene, not a proper blue diluent. Sometimes the blues can also be so dark that their coats and noses look almost black. It's hard to tell if these dogs are black or blue.

Jerrrrmm (talk) 20:00, 31 March 2022 (UTC)[article refers to Dr Sheila M. Schmutz]
 * A "butterfly" nose is a bright pink patch on the skin of a dog's nose. The patches are randomly positioned and can cover any number of noses, from a tiny pink blob to almost the entire nose. Butterfly noses are sometimes seen on dogs with extreme white spotted patterns, but usually they are associated with meteorite coloration. Butterfly noses are created when a part of the nose has no pigment (pink is associated with a lack of pigment). The meteorite gene diluted the random portion of pigment in the hair and nose, forming gray areas in the hair and pink areas in the nose. If the dog is BB (liver) and/or DD (dilution), the non-pink part of the nose can be liver, blue or Isabella. In any case, the liver and Isabella's nose are usually very light, sometimes bright pink, so the butterfly nose may not appear in the liver or Isabella meteorite color (the whole nose may just appear pink).

Jerrrrmm (talk) 20:00, 31 March 2022 (UTC)
 * "Dudley nose" is usually used to describe a dog with a loss of pigment on its nose. Typically, the pigment loss on Dali's nose is in the middle and spreads outward, covering almost the entire nose of some dogs. Pigment loss causes the nose to become lighter in these areas, often ending in a dark pink. Dudley's nose will never completely lose its pigment, nor will it be as bright pink as a butterfly's or even a liver dog's. There is always a darker area around the edge of the nose. Dudley noses are common in blacknosed dogs and are particularly associated with the recessive red gene.[article refers to Dr Sheila M. Schmutz]

Eye Colours
In addition to nose colours, the genes also affect the eye colours of dogs. So I would like to expand the group to talk about more about eye colours patterns related to genes.

Amber eyes
Amber eyes usually appear when the eumelanin produced in dogs is diluted or modified by a recessive gene in the B or D series. Therefore, all hepatic dogs (bb) have amber eyes.Amber eyes vary from light brown to yellow, chartreuse, or gray. Dogs with melanin can occasionally see amber eyes.[article refers to Dr Sheila M. Schmutz]

Blue eyes
Genetically, there are four ways a dog can have blue eyes. Three of these are related to pigment loss in coatings.


 * The first possibility is a side effect of the merle gene. Merle dilutes random parts of the paint, including the eyes and nose. This dilution results in a bluish iris, and merle dogs often have blue, walled, or split eyes due to random pigment loss. The higher the dilution of the merle coat, the more likely they are to have blue eyes. Some genetic variants cause heterochromia, which is when a dog has one blue eye and one brown or amber eye.[article refers to Dr Sheila M. Schmutz]


 * The second way blue eyes can appear is when a dog has a lot of white around the eyes. Since the white areas on the coat are places where the cells cannot produce any pigment, if these areas spread to the face, pigment from the eyes and nose may be lost, turning the nose pink and the eyes blue.[article refers to Dr Sheila M. Schmutz]


 * The third way is when dogs are affected by albinism. Blue eyes and a completely pink nose have been shown to be an intermediate form of albinism.[article refers to Dr Sheila M. Schmutz]

Jerrrrmm (talk) 20:00, 31 March 2022 (UTC)
 * Finally, blue eyes can be inherited as a completely independent gene, unaffected by coat color. However, this gene is rare. It occurs occasionally in Border Collies and similar breeds, but is mostly seen in Siberian Huskies. The most common example is that huskies can have one or two blue eyes, regardless of their predominant coat color.[article refers to Dr Sheila M. Schmutz]