My Understanding of
Coat Color Genetics in Dogs
With A Special Emphasis on Anatolian Shepherd Guardian Dogs

by Erick Conard - January 2002
rev. March 2003

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Linked Table of Contents

  1. Anatolian Shepherd Breeding Selection Criteria Overview
    1. The two most important breeding selection criteria
      1. Proven livestock working ability
      2. Superior Flock Guardian temperament
    2. Superior flock guardian ability unifies Anatolian Shepherds
    3. Breed for proven superior genetic health and superior overall confirmation
    4. Color isn't a serious breeding consideration
    5. Dog color genetics as an introduction to dog genetics

  2. Historical Background of Dog Genetics Overview
    1. Clarence C. Little, Sc.D. - older research in classical genetics (1957)
    2. Roy Robinson - newer classical genetics information (1990)
    3. Molecular genetics - both clarifies and contradicts classical genetics

  3. General Genetic Information Overview
    1. DNA and chromosomes
    2. Loci (Locus)
    3. Genes and alleles
    4. Only two allelic spaces per gene locus
    5. Genes code for two different outcomes
    6. Melanin - A skin pigment in the hair affecting coat color
    7. Two types of mammalian hair pigment - eumelanin and phaeomelanin
    8. Melanocytes (from neural crest cells) synthesize melanin
    9. Pigment Pattern Regulation
    10. Coat color gene control overview

  4. Gene Loci in Dogs Overview
    1. Pigment pattern regulation
      1. The "A" and "E" Loci control pigment distribution patterns (also, perhaps, the "Ma" locus)
      2. The "B," "C," "D," "G," and "M" loci modify color by diluting colors
      3. The "S" and "T" loci control the placement of white areas on the dog's body

    2. The "A" Gene Locus (The Agouti Series) controls the degree and placement of black and yellow on individual hairs and body regions by inhibiting eumelanin (black pigment) production

      1. The Agouti Protein (AP) inhibits the production of black pigment
      2. Two promoters are associated with the wild type agouti gene
      3. AS - Dominant Black Allele (2003-It was very recently proven that dominant black isn't in A locus or in E locus, but somewhere else.)
      4. AY - Sable Allele produces fawn with variable amounts of black (in Anatolian Shepherds this color is designated Fawn rather than sable)
      5. aw - "Wolf color" or "Wolf gray" Allele creates a "wolf colored" coat
      6. asa - "Saddle tan" Allele places a black "saddle" on a tan dog's back
      7. at - Black and Tan Allele places tan points on a dog's body
      8. aa - Recessive Black Allele occurs if the Agouti Protein can't be made, resulting in only black pigment production

    3. The "B" Gene Locus selects for black or brown eumelanin

      1. The Brown Locus affects only eumelanin; it codes for an enzyme that completes the final step of eumelanin production from brown to black
      2. B - Dominant "B" (Black) Allele - Selects for production of black eumelanin
      3. bb - Recessive "bb" (Brown) Alleles - produces brown eumelanin without converting the brown to black

    4. The "C" Gene Locus (The Albino Series) a dilution loci which selects from "full color" (pigmentation) through one of a number of "color dilutions" (reduced pigmentations) and affects both eumelanin and phaeomelanin

      1. Tyrosinase - the enzyme responsible for melanin synthesis
      2. True albinos produce no melanin based pigment
      3. C - Dominant "C" Allele - Full Color
      4. cch - Chinchilla Silvering - lightened tone to non-black pigments
      5. ce - Extreme Silvering - approaching white
      6. ch - Himalayan (Not known to occur in dogs) color is dependent on skin temperature
      7. cb - Blue-Eyed Albino
      8. cc - Recessive "cc"Alleles - True (Pink eyed) Albino

    5. The "D" Gene Locus (The Blue Dilution Series) a dilution loci which selects for either "full color" or "color dilution" (pigmentation or reduced pigmentation) and affects both eumelanin and phaeomelanin

      1. D - Dominant "D" Allele - Full Color
      2. dd - Recessive "dd" Alleles - Dilutes Black to bluish gray and lightens reds and yellows

    6. The "E" Gene Locus (The Extension Series) controls the spread of black over the body (controls the distribution pattern of pigment across the body)

      1. ED - Dominant Black Allele - Produces a black dog regardless of the other genes present (2003-It was very recently proven that dominant black isn't in A locus or in E locus, but somewhere else.)
      2. Em - Dominant "Em" Allele - Black mask and ears
      3. E - Dominant "E" Allele - Extends black over the whole body in a pattern dictated by genes from the "A" gene locus (Agouti Series)
      4. ee - Recessive "ee" Alleles - Produce clear reds or yellows with no black hairs (unable to produce black)
      5. Ebr - Brindle Allele - It is now known that Brindle is not located at the E gene locus, but is located elsewhere.

    7. The "G" Gene Locus (The Gray Series) controls graying as a dog ages

      1. G - Dominant"G" Allele - graying
      2. gg - recessive "gg" Allele - no graying is seen

    8. The "I" Gene Locus (The Intensifying Series) a speculative red/yellow dilution locus that intensifies phaeomelanin (A Questionable locus whose effects may be caused by rufus polygenes [discussed below])

      1. Int - Wild Type - with pale phaeomelanin (fawn)
      2. Intm - Slight Intensification (dark fawn or light red)
      3. intm - Intensified phaeomelanin (red)

    9. The "M" Gene Locus (The Merle Series) controls dilution by the irregular placement of light (dilute) and dark (normal) patches of color

      1. MM - Double Merle produces almost white dogs
      2. Mm - Merle pattern produced in eumelanic areas
      3. mm - Normal color (no merling)

    10. The "Ma" Gene Locus (The Black Mask) produces Black Mask and Ears

      1. Ma - Dominant - Produces black mask and ears
      2. ma - Recessive - No mask is produced

    11. The "P" Gene Locus (The Pigment Series) (A Questionable Locus whose effects may actually be caused by umbrous polygenes [see below])
      1. P - Dominant "P" Allele - Full Pigment effect
      2. pp - Recessive "pp" Alleles - Reduces dark (eumelanin) pigment without changing red-yellow (phaeomelanin) pigment

    12. The "R" Gene Locus (The Roan Series) controls a distribution pattern for intermingling white hairs and dark hairs

      1. R - Roan - a dominant gene
      2. rr - Not Roan - a recessive gene

    13. The "S" Gene Locus (The Spotting Series) affects the extent of White Spotting

      1. White spotting in dogs is controlled by genes which alter the migratory pathways of melanocytes
      2. S - Dominant "S" (Self) Allele - The "No spotting" gene
      3. si - Irish Spotting (Dutch Marking in Anatolians) - White collar and blaze with white belly, legs, and chest
      4. sp - Piebald Spotting (Pinto in Anatolians) - Colored patches on a White Background
      5. sw - Extreme White Piebald - A Few Small Colored Spots on a White Background
      6. Robison White Spotting Scale - An alternate theory classifying white spotting using a scale with ten spotting grades.
      7. White Spotting in horses has been extensively studied and is known to be caused by a variety of different gene loci rather than just one locus, as proposed in dogs.

    14. The "T" Gene Locus (Ticking Series) creates spots of mixed colored and white hairs in otherwise white areas

      1. T - Ticking Allele (incompletely dominant)
      2. tt - Wild type allele with lack of ticking

  5. Polygenes Overview
    1. General Information About Polygenes
    2. Rufus Polygenes
    3. Umbrous Polygenes

My Understanding of Coat Color Genetics in Dogs
With A Special Emphasis on Anatolian Shepherd Guardian Dogs

  1. Anatolian Shepherd Breeding Selection Criteria
  2. The Two Most Important Breeding Selection Criteria

    For a serious and responsible breeder of Anatolian Shepherd Guardian Dogs, the two most important breeding selection criteria are proven livestock working ability and superior flock-guardian temperament. Anatolian Shepherds without both livestock working ability and superior flock-guardian temperament are Anatolians in name only and should not be considered for use in any responsible breeding program.

    Superior Flock Guardian Ability Unifies Anatolian Shepherds

    Anatolian Shepherds (i.e. Turkish Shepherds' Dogs) have existed in Turkey for more than a millennium as superior working flock-guardians possessing a wide range of diversity in both structure and color. The factor which unifies these "Turkish Shepherds' Dogs" is their uniquely superior flock-guardian ability.

    Breed for Proven Superior Genetic Health and Superior Overall Confirmation

    After eliminating all Anatolians except for those with proven livestock working ability and superior flock guardian temperament, the serious and responsible Anatolian breeder's next set of criteria will include only those Anatolian Shepherds with proven superior genetic health and superior overall confirmation. Over time, placing confirmation and genetic health above working ability and temperament in the breeding selection criteria will change the essential nature of this amazing breed and will result in Anatolians being just another breed of large, beautiful, and potentially dangerous pets without any real working ability.

    Color Isn't a Serious Breeding Consideration

    In breeding Anatolian Shepherd Guardian Dogs, color should never be a serious consideration in the breeding selection process.

    Dog Color Genetics as an Introduction to Dog Genetics

    Color genetics, however, is an interesting and relatively easy first step into more complex aspects of dog genetics. In addition, there have been some impressive advances recently in our understanding of mammalian color genetics, including dog color genetics. The colors expressed in each dog's coat are unambiguously stamped into the genetic code found in that dog's chromosomes. This article's goal is to provide a general overview of coat color genetics in dogs and to highlight coat color genetics in the Anatolian Shepherd Guardian Dog.

  3. Brief Historical Background in the Development of Dog Genetics
  4. Clarence C. Little, Sc.D.

    Clarence C. Little, Sc.D., provided most of the published information regarding the genetic basis of coat color in dogs based on older research in classical genetics. He wrote The Inheritance of Coat Color in Dogs, published in 1957. Dr. Little worked in and later owned the 20 -100 dog private kennel founded by his father. For sixteen years Dr. Little performed experiments in breeding for coat color at the Jackson Laboratory, which maintained some 200-220 dogs of 28 breeds and produced over 4,100 puppies.

    Roy Robinson

    More recent dog coat color information using classical genetics was provided by Roy Robinson in his book, Genetics for Dog Breeders (2nd ed.), 1990.

    Molecular Genetics

    Our understanding of dog coat color genetics is being greatly expanded by the advances made in molecular genetics. Molecular genetic research in mouse coat color has been quite extensive and since coat color appears to be highly conserved across mammals, much of the information obtained regarding mouse coat color can be applied directly to dog coat color genetics. Dog coat color genetic models formulated from information obtained using molecular genetics research have in some cases clarified and in other cases contradicted the classical genetics models formulated by C.C. Little.

  5. General Genetic Information
  6. DNA and Chromosomes

    DNA is found in the cells of most living things. DNA consists of strands of material called chromosomes which are composed from a series of sequences of four chemicals. Chromosomes are arranged in pairs. Each member of a pair has the same basic structure except for the fine details.

    Loci (Locus)

    Along each chromosome in a pair are corresponding sections called loci (plural) or locus (singular). Each locus of each chromosome relates to some structure or function of the living entity. Since chromosomes are paired, for each locus on one chromosome there is a corresponding locus on the other chromosome of that chromosome pair.

    Genes and Allelles

    A gene consists of a specific sequence of the chemicals occupying a locus. The members of the set of genes that could possibly occupy a specific locus are called alleles of that locus; alleles are all alternate gene possibilities found at identical loci on the chromosomes.

    Only Two Allelic Spaces per Gene Locus

    Some gene loci have only two possible allelic choices, essentially resulting in either an "either/or" outcome or a blending of the two possible allelic instructions, depending on the dominance relationship of each allele. Other gene loci have a larger number of possible allelic choices. However, no matter how many different allelic choices are possible at one locus, only two allelic spaces are available to be filled per locus (one allele on each chromosome). The outcome of the interaction between these two alleles results the gene's phenotypic (or outward) expression.

    Genes Code for Two Different Outcomes

    It is important to remember that genes code for two different outcomes. While one type of gene codes for the structure of a particular protein, another type dictates when and where associated genes are turned on or off.

    Melanin - A Skin Pigment in the Hair Affecting Coat Color

    Coat color is affected by pigment in the hair. The biosynthetic pathways involved in the synthesis of pigments, and the genes involved in the development of the pigment forming cells (melanocytes), the hair follicle, and the hair shaft, appear to be very similar in most species. Mammalian pigmentation is due primarily to the presence of melanin, a skin pigment.

    Two Types of Mammalian Hair Pigment - Eumelanin and Phaeomelanin

    There are two types of pigment in mammalian hair, eumelanin, a black-brown pigment, and phaeomelanin, a yellow-red pigment. These two pigments are both forms of melanin synthesized by the melanocytes. Eumelanin is dark (black or brown) and varies somewhat in color due to variations in the protein that forms the framework of the pigment granule. The base form of eumelanin is black. The brown form is often called liver in dogs. Pheomelanin is light (yellow, tan, or reddish) and varies from pale cream through shades of yellow, tan and red to mahogany (as in the Irish Setter). Both melanins are made by a similar process and the first few steps in their synthesis are identical. Mutations that affect these identical steps affect both melanins while mutations that affect steps after their synthesis pathways diverge will affect only one melanin or the other.

    The starting material in melanin synthesis is the colorless amino acid tyrosine. Tyrosinase, an enzyme by some believed to be encoded from the "C" Locus (The Albino Locus), converts tyrosine to DOPAquinone, which is also colorless. Phaeomelanin is made from DOPAquinone by enzymes that attach the amino acid cysteine to the DOPAquinone and then polymerize the resulting compounds into masses with a color from yellow through red. Eumelanin is made with the same initial steps. However, the DOPAquinone is converted to DOPAchrome, which is converted to complex quinone compounds by the enzyme tyrosinase related protein I (TYRP1, produced at the B Locus by the brown gene), either directly or after an intermediate step with another enzyme, DOPAchrome tautomerase (DCT, believed to be produced by one of the dog dilution genes). The quinones are then polymerized into eumelanin.

    Melanocytes (From Neural Crest Cells) Synthesize Melanin

    Melanin is synthesized in specialized cells called melanocytes, which live in hair follicles. Melanocytes originated from the neural crest cells located on the dorsal mid-line during the early embryonic stage of development. The neural crest cells have genetic instructions to become a variety of different organs and tissues. If the neural crest cells directed to become melanocytes misinterpreted their instructions or mutated and received the wrong instructions, they might do some new task or perhaps do nothing, creating an animal with partial or no pigmentation in the hair or skin. Therefore, some melanocytes contain skin pigment while others don't. Where there is no skin pigment, white hairs will be produced.

    The melanocytes synthesize melanin, form it into granules, and deposit it into the hair shaft. Color variation of the hair can occur either from alterations in its synthesis or variation in the deposition of the pigment. The color of the pigment granule is dependent on the type and amount of pigment (melanin) in it. The hair shaft can have greater or lesser amounts of granules deposited in it, producing variation in shade and intensity of color. The color and density of pigment granules can vary between individual hairs as well as varying in locations along the length of the hair shaft in a single hair.

    Coat Color Gene Control Overview

    Coat color is affected by genes which dictate the size, shape, position, number, and arrangement of the melanin granule in the hair (i.e. a denser granule arrangement lightens hair). Genes also affect the type of melanin the coat hairs contain. The structure and texture of the hair and the intracellular environment also affect coat color. Further, the same genes may result in very different effects on different types and lengths of coat.

    In general, genes that control dog coat color:

    1. Produce either black-brown or yellow-red pigment in the coat hairs;
    2. Alter the base color pigments to produce a modified base color;
    3. Dictate the assigned body locations for different colors;
    4. Control specific color placement, including variations, on individual hairs; and
    5. Fail to code for color pigment, resulting in the production of white hairs.

  7. Gene Loci in Dogs
    1. Pigment pattern regulation

    2. Three groups of genes regulate the pattern of pigment in individual hairs and across the body.
      1. The "A" and "E" Loci control pigment distribution patterns (also, perhaps, the "Ma" locus). The "A" (Agouti) Locus, which blocks black, and the "E: (Extension Locus), which controls the extent of the extension of black across the coat, dictate the distribution pattern of eumelanin (black/brown) and phaeomelanin (red/yellowo) pigment in the coat. The gene controlling brindle and the gene controlling black mask might also be included as pigment distribution pattern loci. These gene loci control pigment distribution patterns without contontrolling the actual color of the pigment.

      2. The "B," "C," "D," "G," and "M" loci modify color by diluting colors The dilution loci are a variety of less well understood genes which modify the color of the eumelanin and phaeomelanin pigment. Some of these loci are "B" (Brown) Locus, "C" (Albino) Locus, "D" (Blue Dilution) Locus, "G" (Gray) Locus, and "M" (Merle) Locus. The "C" Locus is the only gene location that fully affects the synthesis of both melanins. The other genes primarily affect eumelanin synthesis. Although no gene has as yet been identified that affects primarily phaeomelanin synthesis, an intensifier loci and the loci for "fawn" are possibilities. All of the dilution loci interact in what seems to be a cumulative manner (as the total number of dilute genes increases the coat appears progressively lighter). Dilution loci control the color of the eumelanin and phaeomelanin pigments but not their distribution patterns.

      3. The "S" and "T" loci control the placement of white areas on the dog's body. More specifically, The "S" (White Spotting) Locus and the "T" (Ticking) Locus (which actually may be an allele of the "S" locus) control the prosence, location and size of white (unpigmented) areas.

    3. The "A" Gene Locus (The Agouti Series) controls the degree and placement of black and yellow on individual hairs and body regions by inhibiting eumelanin (black pigment) production. In general, more yellow is dominant over more black.

      1. The "A" (Agouti) Locus Can Block Black by producing the Agouti Protein

      2. The "A" locus (Agouti Series) is the most important color locus in dogs and contains between four to six different alleles. The Agouti (A) gene was recently cloned. In mice, this gene has a large number of alleles whose synthesis is under complex regulation. The basic function of Agouti locus genes is to code for the production of a small signaling protein, the Agouti Protein (AP), to be secreted from dermal papilla cells in the hair follicle. This protein attaches to the MC1R receptor on the melanocytes, blocking the Melanocyte Stimulating Hormone (MSH) from binding on the MC1-R receptor and causing the melanocytes to produce a low level of tyrosinase. Low tyrosinase levels result in phaeomelanin (yellow/red) production rather than eumelanin production. Therefore, when the Agouti gene is present, melanocytes produce mostly phaeomelanin and much of the coat is some shade varying between dark red through pale yellow. The agouti pattern is a mostly red/yellow pattern that supercedes the dog's underlying genetically directed solid black color. As a rule, agouti genes don't alter the dog's skin color since skin melanocytes aren't regulated by MSH and don't use the MC1R/agouti system.

      3. Two promoters are associated with the wild type agouti gene.

        1. Two promoters are generally associated with the "wild type" version of the agouti gene. One promoter (the cycling promoter) produces a banded hair with a black tip and yellow middle over the entire body. The other promoter (the ventral promoter) directs that there be only yellow color in the hair but only in the hair on the belly. So the animal will have black banded hair on the dorsal surface and paler yellow hair on the ventral surface.

        2. The action of these two promoters can be interrupted independently. If only the action of ventral promoter is disrupted, the dog's hair will be banded over its entire body (solid agouti). If only the action of the cycling promoter is disrupted, the dog's back will be black and its belly will be yellow (which produces the black and tan.)

        3. If both promoters are disrupted or some other alteration inactivates the agouti protein, the animal appears solid black.

        4. Also, a promoter mutation can occur that causes the yellow to be expressed over most of the body surface.

      4. AS - Dominant Black Allele (It was very recently proven that dominant black isn't in A locus or in E locus, but somewhere else. )

        1. The traditional belief is that domestic dogs have a dominant black allele, AS, at the "A" locus. No other mammal has dominant black at the "A" locus and the dominance hierarchy in general moves from less dark pigment to more dark pigment as the alleles become increasingly recessive. Dominant Black at the "A" locus would violate that trend. As a rule, more yellow is dominant to more black.

        2. Dominant Black was placed in the Agouti series by Little. However, all other mammals have Dominant Black in the Extension "E" Series (see below), rather than in the Agouti series. It is unlikely that dominant black is actually in the Agouti series in dogs for these and other more empirical reasons relating to the genetic mechanism at this locus. Therefore, until recently (2003)it had been considered that Dominant Black should be placed under "ED," Dominant Black, in the "E," Extension Series.

        3. When dominant black is present, the dog is able to produce only eumelanin pigment.

        4. This allelic assignment, AS as "Dominant Black," was recently reevaluated and is incorrect. It was very (2003) recently proven that dominant black isn't in the A gene locus or in the E gene locus, but somewhere else.

        5. Note that in the "A" series some authors use the AS designation for the Sable allele instead of using AS incorrectly for Dominant Black allele (Also see "E" series for Dominant Black). In this document, the Sable allele is designated AY.

        6. It has been speculated that the decreasing order of dominance of the alleles at this locus are AY, asa, at aw, and aa. (The dominance order of these genes has not yet been verified with certainty.) The last allelic pair, recessive black (aa), is extremely rare but has been observed in German Shepherds and perhaps Shetland Sheepdogs. Sufficient coat color information on Anatolian Shepherds has not been collected and examined to eliminate the presence of recessive black (aa) in Anatolians.

      5. AY - Sable allele produces fawn (yellow/red) with variable amounts of black.

        1. In Anatolian Shepherds, the almost universally found allele of the "A" series is the sable allele, AY. Anatolian Shepherd owners use the term "fawn" rather than sable to describe this color. The AY , or sable, allele produces fawn colored dogs from phaeomelanin (yellow/red) color pigment because the sable allele inhibits eumelanin (black). Depending on other genetic color factors, the sable allele can result in a dog with a color range anywhere from a pale biscuit through shades of yellow to a rich red. The sable allele can produce varying amounts of black hair ranging from solid black to black tipped and varying in body placement. Generally, a sable Anatolian Shepherd is mostly yellow/red (phaeomelanin) with some black tipped hairs. Both black and yellow/red pigment can be found on the same hair. Even if there is no black in the dog's coat, a sable dog's whiskers (the stiff vibrissae) originating from pigmented skin are black. The sable allele also permits the production of some longer black (especially on the dorsal surface) hairs (which can be called sailing) on the fawn background. This allele also permits a black mask and ears and possibly brindle.

        2. Phaeomelanin is apparently the "default" pigment when the production of black pigment is suppressed. Therefore, without other gene directed enzymatic and regulatory activity, a dog's coat will become some shade of yellow. Pigment modifying factors can result in yellow phaeomelanin shades anywhere from light cream to dark red color variants. For phaeomelanin production, the enzyme tyrosinase converts tyrosine into a compound named DOPAquinone. The genes directing the final steps to phaeomelanin production have yet to be clearly delineated.

      6. aw - "Wolf-color" allele (or ag - Wolf-gray allele) creates a wolf colored coat.

        1. This allele's effect is most clearly observed in the coats of Norwegian Elkhounds. In the "A" series of most mammals, the agouti (a+) allele is generally considered as the wild-type allele. However, in dogs (aw) [sometimes designated (ag)] perhaps best serves the function of the wild-type allele. Currently, we do not know how similar or different the a+ alleles and the aw alleles are.

        2. The aw allele varies from the AY (sable) allele in two notable ways. The yellow/red is replaced by a pale cream to pale gray color and the hairs are banded with several bands of alternating light and black pigment rather than the scattered black tipped hairs seen in sable.

      7. asa asa - "Saddle tan" allele places a black "saddle" on a tan dog's back

        1. This color is seen in many terrier breeds having a black "saddle" on their back and extensive tan on their legs and head.

        2. Some believe that, rather than being a separate gene, the saddle tan allele is a variation of the black and tan allele that produces a small amount of black across the back due to the effect of modifiers.

      8. at at - Black and Tan allele places "tan points" on the dog's body

        1. "Tan points," composed of hair with only yellow/red (phaeomelanin) pigment, are placed on the cheeks of the muzzle, the chest, the end of the legs, around the anus under the tail, and on the eyebrows.

        2. Only black (eumelanin) pigment is found in hair in all other body regions.

      9. aa - Recessive Black allele occurs if the Agouti Protein can't be made, resulting in only black pigment production.

        1. The recessive black allele (aa) is a mutation that results in the loss of ability to synthesize the Agouti Protein (AP), which inhibits the production of black pigment. Without the inhibition of black pigment production, only eumelanin (black pigment) is produced by the melanocytes.

        2. This same type of mutation results in "recessive black" (aa) in horses, mice, fox, and many other mammals that have a solid black color variant originating from the "A" Series.

        3. Since black is the most recessive color in the "A" series in other mammals, it seems reasonable to believe that recessive black in dogs is also in the "A" Series and is also the most recessive color. Therefore, it is currently believed that recessive black is produced by "aa" at the Agouti Locus.

    4. The "B" Gene Locus (Brown Series) produces either black or brown eumelanin

      1. The Brown Locus affects only eumelanin (affects only black/brown, not red/yellow). In mice, the Brown Locus, codes for an enzyme, tyrosinase-related protein 1 (TYRP1), which catalyzes the final step in eumelanin production, changing the final intermediate brown pigment (dihydroxyindole) to black pigment. It is believed that this gene, using the same mechanism, is also responsible for the expression of brown in dogs.

      2. "B" - Dominant B (Black) - The dominant gene (B) directs the color of eumelanin produced to be black. This direction includes the black color seen on the body, masks, ears, brindle stripes, etc. Pigmented skin areas (like the nose leather, lips, and eye rims) are black.

      3. "bb" - Recessive "bb" (Brown) - The recessive gene (bb) directs the color of eumelanin produced to be a chocolate brown but does not take the final step in eumelanin production of changing brown to black. Phaeomelanin (yellow/red) isn't affected. The pigment granules produced by "bb" are smaller, rounder in shape, and appear lighter than pigment granules in "B" dogs. Pigmented skin areas (like the nose leather, lips and eye rims) are brown, not black. Also, the iris of the eye is lightened. Some "liver" and "chocolate" colored dogs, especially in the sporting breeds, carry the "bb" gene. This is also the gene responsible for "reds" in Dobermans (bb) and perhaps the bronze Newfoundlands.

        In the "bb" recessive brown Anatolian Shepherd with an AY sable (fawn) coat (the most commonly seen Anatolian coat color), the coat will be shaded with brown rather than with black. The "bb" will perhaps result in a fawn that has an orangey cast with light brown eyes, brown nose leather, and brown eye rims. The only Anatolian Shepherd I have personally seen that I believe carried the "bb" recessive brown (light brown eyes, brown nose leather, and brown eye rims) was a pale white-cream colored dog called Blue. Blue's eyes remained blue until he was four months old and gradually became a yellowish brown color.

      4. Note:
        1. Some shades of liver (brown), expressed through "bb" eumelanin (black/brown) pigment, overlap some shades of tan (yellow/red), a phaeomelanin pigment.
        2. The "B" locus acts only on eumelanin (black) pigment.
        3. The "C" locus has the strongest effect on phaeomelanin (red/yellow) pigment.
        4. The "D" locus affects both phaeomelanin (red/yellow) and eumelanin (black) pigment.

    5. The "C" Gene Locus (Albino Series): a dilution loci which selects for color across a range from full color through no color. More color is incompletely dominant over less color. It is the only gene location that fully affects the synthesis of both melanins.

      1. Tyrosinase is the enzyme responsible for the initial step in melanin synthesis.

        1. Both types of melanin, eumelanin and phaeomelanin, depend on the enzyme tyrosinase for their production. In mice, the chinchilla (cch) allele produces a defective tyrosinase which synthesizes abnormally low quantities of melanin. The melanin synthesized tends to be the dark eumelanin. Although the degree of lightening varies by species, the eyes and nose generally remain dark.

      2. True albinos produce no melanin based pigment

        1. Current thought is that a true albino, whose melanocytes produce no melanin- based pigments, results from a complete malfunction in tyrosinase production. While CC or Cc dogs' coats have full color, as directed by their other color genes, albino (cc) dogs' coats are homozygous for a recessive mutant allele. Albinos, who have no pigment, are either very rare or non-existent in dogs.

      3. The following potential alleles have been suggested for the "C" Series in dogs:

        1. "C" - Full color - the dominant allele in the "C" series. This allele allows for the expression of full color. "C" is the only allele of this series which is present in most breeds and is probably the structural gene for tyrosinase.

        2. "cch" - chinchilla silvering. It is incompletely dominant. Chinchilla imparts a lightened, flat tone to non-black pigments without greatly affecting black. (In dogs, the chinchilla gene lightens yellow, tan or reddish phaeomelanin to cream but has little noticeable effect on the dark eumelanin, so it affects phaeomelanin more strongly than eumelanin and brown or dilute eumelanin more strongly than black eumelanin, to the point that it has little effect on solid black dogs. Under it's influence, brown becomes milk chocolate, blue becomes silver, and red phaeomelanin lightens toward cream.)

          The "chinchilla" gene may be a factor affecting the coat color of some of our light Anatolian Shepherds. Those breeders with very light colored dogs may wish to consider this possibility and help determine how prevalent, if present at all, this gene is in the Anatolian Shepherd.

          NOTE! Recent genetic information indicates that although a chinchilla-like mutation occurs in dogs, tyrosinase activity hasn't been shown to be connected. Therefore, some other factor may be at play and the dog chinchilla allele may not belong in this series. Also, there may be more than one form of the chinchilla gene; for instance, rabbits are thought to have three different chinchilla alleles.

        3. "ce" - (extreme dilution) represents an extreme silvering, approaching white. If this gene exists, it might be responsible for the lightest colored Anatolian Shepherds. Some white dog breeds may be produced by this gene where the white results from the extreme dilution of yellow/red (phaeomelanin). For example, the West Highland White Terrier may be (cece)(ee). This gene (ce) does not appear to lighten eyes in dogs.

        4. "ch" - Himalyan - isn't known to occur in dogs but is an interesting allele in the C series. When homozygous (chch), the formation of eumelanin becomes dependent on skin temperature. A genetically solid black animal has reduced black on extremities (seal brown) and an almost white coat on the body.

        5. "cb" - blue-eyed albino - Blue-eyed albino and true pink-eyed albino are very rare in any dog breed, if present at all. However, it may be responsible for the pink skinned, blue eyed white Doberman.

        6. "c" - true pink-eyed albino - not documented as occurring in dogs but in other mammals it stops melanin formation completely, including skin, coat, and eyes, resulting in a pink eyed white animal. "c" directs production of a form of tyrosinase that doesn't function properly in melanin formation. There can be a number of different forms of "c" since there are a number of ways for something to not work properly.

        1. The "B" locus acts only on eumelanin (black) pigment.
        2. The "C" locus has the strongest effect on phaeomelanin (red/yellow) pigment.
        3. The "D" locus affects both phaeomelanin (red/yellow) and eumelanin (black) pigment.

    6. The "D" Gene Locus (The Blue Dilution Series): a dilution loci that controls the dilution of eumelanin and phaeomelanin.

      1. "D" - wild type; normal color - the dominant allele codes for full color pigmentation.

        The full color allele at the "D" gene locus is called "D."

      2. "dd" - blue dilute; the recessive allelic pair codes for dilution of black and yellow/red pigment. In some breeds "dd" has been associated with skin problems.

          In general, "dd" acting on phaeomelanin coat color seems limited to breeds in which color is of little importance (as is true in Anatolian Shepherds). Phaeomelanin responds by producing a flattened or dulled coat color.

          The recessive allelic pair, "dd," dilutes eumelanin (black) pigment into a gray-black or bluish gray and also lightens and dulls phaeomelanin (reds and yellows) to a silvery or flat shade of the yellow through red color. Pigmented skin will also be a lighter blue or gray color and the irises may be a lighter brown or gold.

          Although rare in Anatolians, "dd" has been observed. It is most easily noticed in "blue masked" (rather than black masked) Anatolians. Black dogs with the recessive "dd" are sometimes called "Maltese blue." A pure liver dog (chocolate brown - bb) that also carries "dd" results in the silvery blue color of Weimeraners or isabella Dobermans (sometimes called fawn, in Dobermans, and also lilac colored in other breeds). In Anatolian Shepherds and other dog breeds, fawn refers to the yellow and black sable coat color produced by the Ay allele.

          Some believe that the dilute color produced is from the same genetic origin (bbdd) that produces color in the dilute trait in mice. It is a mutation of myosin V, a motor protein that's involved in transport of the pigment granules in the melanocytes. The pigment granules are normal but inefficiently deposited.

          However, others believe that the dog dilute trait isn't caused by this mechanism. Instead, they believe that this color is caused by a mechanism similar to the "slaty" mutation in mice, which involves a mutation of DOPA chrome tautomerase (DCT). This DCT mutation in mice results in a paler, grayish coat.

      1. The "B" locus acts only on eumelanin (black) pigment.
      2. The "C" locus has the strongest effect on phaeomelanin (red/yellow) pigment.
      3. The "D" locus affects both phaeomelanin (red/yellow) and eumelanin (black) pigment.

    7. The "E" Gene Locus(Extension Series): Controls the distribution pattern of pigment (the degree and placement of black and yellow on individual hairs and body regions) by controlling the extension of black pigment across body regions of the coat.

      1. The Extension of Black Color Across the Coat

      2. The "E" Locus (Extension Series) has been cloned and sequenced. It encodes for production of the melanocyte stimulating hormone receptor, or melanocortin 1 receptor (MC1R). MC1R is a protein attached to the surface of melanocytes that controls the amount of tyrosinase melanocytes produce. A small protein in the blood, alpha melanocyte stimulating hormone (MSH), binds to the MC1R receptor and passes a signal to regulatory factors inside the cell, causing the melanocyte to increase the level of tyrosinase.

        Tyrosinase is the limiting enzyme involved in melanin synthesis and when found at high levels eumelanin (black/brown) is produced. Low tyrosinase levels result in phaeomelanin (yellow/red) production. Because MSH is always present in relatively high levels in dogs, all dogs would be solid black without the influence of other coat color genes.

        This two step mechanism to produce solid black may be related to the fact that in many wild animals melanocortin levels vary seasonally, causing their coat colors to vary seasonally. When coat color is linked to seasonally variable melanocortin levels, you may have animals with a white winter coat and a dark summer coat. Dogs, however, maintain fairly constant (and high) levels of MSH so don't exhibit seasonal color changes.

        The "E" Locus (Extension Series) has the following alleles:

      3. "ED" - Dominant Black: It was believed that Dominant black results from a mutation of the MC1-R protein that causes the melanocytes to believe they are receiving a signal even though they aren't. With dominant black, only eumelanin is synthesized, resulting in a black dog (if eumelanin dilution modifiers aren't present). This mutation was referred to as dominant black because it was believed to be the dominant allele at the "E" Locus. However, it was very recently proven that dominant black isn't in either the A gene locus or in the E gene locus, but somewhere else.

        It's important to remember, however, that not all black dogs are dominant black. Some black dogs are produced by recessive black, the (aa) alleles found at the A Locus (the Agouti Series).

      4. "Em" - Black Mask and Ears is believed to be the dominant allele in this series.

        "Em" is a gene which attempts to produce a black mask and ears, but restrict the rest of the coat to the yellow-red range. Whichever gene causes black mask, most Anatolian Shepherds have it.

      5. "E" - Wild Type: capable of producing both pigments. This allele allows the melanocytes to respond to the signals from other cells and tissues and is the gene for extending black pigment over the whole body. Under the influence of other genes the expression of black may be suppressed.

      6. "ee" - Recessive Red/Yellow, the non-extension gene: This allele is a mutation which codes for a total loss of function in homozygous (ee) dogs. "ee" produces a defective MC1-R protein that can't pass on the signal from MSH, so the melanocytes synthesize only phaeomelanin. Because it is recessive to the others, the gene pair has to be "ee" for it to have any effect, but in that case, it produces clear yellows or reds with no black hairs at all.

        Genetic testing on dogs has shown that pure red/yellow, cream, and white can be produced by genetically "ee" dogs. This gene may exist in Anatolians. It may be the gene that produces dogs without masks.

      7. "Ebr" - Brindle: It is now known that brindle isn't at the E gene locus, but somewhere else.

    8. The "G" Gene Locus (Gray Series): Controls the dilution of black to white in individual hairs.

    9. Although the dog trait for gray doesn't closely match any mouse traits for gray, it is similar to a mutation of the mouse TYRP1 gene. This mutation in mice causes the enzyme to produce a toxic intermediate that eventually kills the melanocyte. Young melanocytes produce dark, fully pigmented hair tips but as the melanocytes slowly die the hair color fades until it is nearly white at its base. When the hair falls out, melanocyte stem cells in the hair follicle produce new melanocytes and the cycle repeats itself.

      Little recognized only two alleles for gray:

      1. "G" - Dominant "G" Allele - Graying: graying occurs as the animal ages.

        "G" or "Gg" animals have eumelanic (black)areas of the coat that lighten slowly with age to blue-gray in a manner similar to premature graying in humans.

      2. "gg" - Recessive "gg" Allele - Wild Type: no graying is seen

      However, this series is almost certainly more complex and should have more alleles or is a generalized trait that is affected by more than one locus. For example, another potential graying locus that is seen in Anatolian Shepherds is the gene that controls graying of the muzzle and over the eyes of aged dogs with black masks. This locus doesn't affect the dog's skin or phaeomelanic (yellow) hair. Graying may begin as early as immediately after birth or be delayed for weeks, months, or years and may reach its most faded state by the first adult coat or continue throughout the animal's lifetime.

    10. The "I" (Intensifier Series) Locus: Controls the synthesis of phaeomelanin (a red/yellow dilution locus) without changing eumelanin (black) pigment.

      1. The speculative "I" gene locus is not well understood. However, dogs are descended from wolves, which have paler phaeomelanin pigment than found in many dog breeds. Anatolian Shepherds commonly have very pale phaeomelanin pigment. Some breeding experiments indicate that the pale "wild type" phaeomelanin typical of wolves is dominant to the "intensified" red phaeomelanin common in many modern dog breeds.

      2. The intensifier locus is a possible gene influencing the synthesis of phaeomelanin. However, this simple scheme using only three alleles and one locus may be far too simplistic.

        1. wild type (pale phaeomelanin)
        2. Intm - slight intensification (intermediate color)
        3. int - intensified (red)

    11. The "M" Gene Locus (Merle Series): Controls the dilution of the dog's coat in a patchy pattern of normal and dilute color.

    12. Merle is an intermixed or patchy pattern of various light and dark areas in eumelanic (black)areas of the coat. Merle does not affect phaeomelanin (red/yellow). Merle has two related patterns:

      1. harlequin, where an additional merle modifying dominant gene (most commonly associated with Great Danes) turns the lighter patched areas white. Harlequin Great Danes continue to produce merles, which indicates that animals pure for this gene may not exist. It is believed that this gene, when homozygous, is an embryonic lethal.

      2. tweed, where another additional merle modifying dominant gene makes the light areas have different intensities. This gene is seen in Australian Shepherds

      Merle acts only on eumelanin (black pigment), not on phaeomelanin (red/yellow pigment). Under the influence of the merle gene, a black coat becomes gray splotched with black and a liver coat becomes dilute red patched with liver. Liver is black (eumelanin) acted on by "bb," the Brown Series dilution gene. These patches or splotches are large and clear because they are clonally derived (a specific black area is populated by melanocytes descended from one melanoblasts [immature melanocyte] from which the transposon excised cleanly.

      The lighter patches in a merle dog result from either melanocytes containing transposons in one of the merle alleles or melanocytes from which the transposon inaccurately excised. The black areas contain melanocytes in which the transposon excised cleanly enough to restore full gene function. In adult dogs it is difficult to distinguish sable merles from sables. Merle is clearly visible at birth but fades with age.

      Merle (M) (as well as Spotting [S]) results from genes affecting the melanocytes' migratory pathways which have provided the "wrong" signal or which have interpreted the signal incorrectly due to a mutation. Merle acts as a "minus" modifier for alleles of the "S" Locus (Spotting Series).

      Merle is an example of incomplete dominance (a gene with intermediate expression):

      1. "MM" - Double Merle alleles produces almost white dogs: These dogs have more white than is normal for the breed (they are almost all white). They may also have hearing losses, vision problems, brain defects, and perhaps infertility, indicating that the merle gene is not solely a pigmentation gene. If "MM" is present in the presence of a white spotting gene, these physical problems seem to be far worse.

      2. "Mm" - This combination results in a dog with the merle pattern in eumelanic areas: The eyes of an Mm dog can be blue or merled (brown and blue segments in the eyes).

      3. "mm" - Normal color - No merling is seen in the dog.

      An interesting theory is that merle is a "fragile" gene that easily allows the merle (M) gene to mutate back into the non-merle (mm) gene. This "fragility" may be caused by a transposon, which is a small mobile "parasite" DNA element similar to a virus. Rather than infecting other animals, the transposon infects the host's offspring.

      Much mammalian DNA consists of inactive "dead" (mutated) transposons, which are found in nearly all animals. Active transposons are a major cause of mutations. Transposons can move around. When they "jump into" a gene they can disrupt its function.

      The transposon responsible for merle is called "non-replicative," meaning that when it "jumps out" of a location function may be restored to its host gene. More often, the transposon excises sloppily and leaves an irreparably damaged gene behind. If the transposon excises cleanly in a cell that goes on to become a sperm or ova, offspring conceived from that germ cell will revert to wild-type.

      The coat pattern of merles (Mm) would occur as some clonal descendants would be from migrating melanocytes which reverted from (Mm) to (mm) as they migrated to their final location in the skin, producing black patches, while other clonal descendents from other migrating melanocytes would have remained (Mm), producing the lighter patches.

      This theory also explains why occasionally a double merle (MM) bred to black can produce a black puppy. When this occurs the mutation most likely occurred in a germ cell. Of course, this solid black puppy can also be (Mm) genetically but have such large patches of black that merling patches are hidden.

    13. The "Ma" Gene Locus (Black Mask Series): Codes for the presence or absence of a black mask and ears (a distribution pattern).

    14. This is the gene now believed to control the presence or absence of a black mask and ears rather than Em in the "E" gene series. The expression of this gene is commonly seen in Anatolian Shepherds.

      1. Ma - dominant: produces a black mask and ears. This gene directs the distribution of eumelanic (black) pigment over the dog's nose and sometimes the ears, top of the back, chest, tail, and /or feet. The range of distribution of eumelanic hair varies from only a small amount of darkening at the muzzle through an extensive spread across the dog's body. It is believed that this wide variation is caused by several different alleles for black mask, a number of modifier genes, or both. Black mask is now believed to be dominant to agouti while white spotting is dominant over black mask. It is common for black mask marking to fade or reduce in size as the puppy ages.

      2. ma - recessive: no mask is produced

    15. The "P" Gene Locus (Pigment Series): Controls the density of dark pigment (a dilution loci) without changing red-yellow pigment.

      1. Some have speculated there is a color locus, "P," which acts on the dark (eumelanin) pigment in such a way that a homozygous recessive expression (pp) at this locus will greatly reduce the dark pigment of the coat without changing the red-yellow pigment.

      2. P - Dominant - full pigment effect

      3. pp - Recessive - reduces dark (eumelanin) pigment without changing red/yellow (phaeomelanin) pigment.

      4. However, others believe that modifiers increased and decreased the pigment intensities for both eumelanin and phaeomelanin.

        A third possibility discussed is that the observed effect described here is from the umbrous polygenes rather than a speculative "P" Gene locus.

    16. The "R" Gene Locus (Roan Series): Controls a distribution pattern for intermixed white and colored hairs.

    17. If a pattern of intermixed white and colored hairs occurs throughout the coat, the coat is called roan. However, if colored areas are in a white background and contain no white hairs, these colored areas are called ticking or flecking.

      The Roan Series may or may not be a true series. Instead, it may simply be an allele of the Ticking Series that produces very fine ticking. Like ticking, roan seems to be dominant over non-roan. Therefore, it might be best if roan were treated as an allele of the Ticking Series rather than placed in its own Series.

      There are two ways roaning develops. Dark hairs may appear in an initially white area or white hairs appear in an initially dark area (which may also be caused by the gray gene).

      Two alleles are generally identified in the Roan series.

      1. "R" - Roan - a dominant gene

      2. "rr" - Not Roan - recessive

    18. The "S" Gene Locus (Spotting Series): Controls a distribution pattern for white by affecting the degree of White Spotting

      1. White spotting in dogs is controlled by genes which alter the migratory pathways of melanocytes. Melanocytes originate from the neural crest cells, which are found along the midline of the back early in embryonic development and which develop into a number of different cell types, including much of the peripheral nervous system. Most of the connective tissues, cartilage, and bones are generated from the cranial neural crest cells, which are found in the embryonic head area.

        A reduced number of melanocytes are formed if the number of neural crest cells is lower than normal because the other, more important, cell locations are favored over the melanocytes. These immature melanocytes (called melanoblasts) spread outward from the dorsal midline over the surface of the animal. Therefore, in mutations that affect the number or migratory pathway of melanoblasts, melanocytes are most likely to fail to reach areas further from the dorsal midline (feet, chest, and muzzle), resulting in white spots at these locations.

        In Anatolian Shepherds, the S Locus may be seen in colors ranging from solid (no white), to Irish Marked (called "Dutch Marked" in Anatolian Shepherds), to piebald ("pinto" in Anatolian Shepherds), to solid white. The great variability within each type makes it unclear how many alleles actually occur at this locus. Modifying genes (see polygenes below) greatly affect the expression of the spotting gene.

        A recessive gene is required to place white on a dog's coat. The recessive spotting gene alleles, which all code for some degree of white spotting, exert only incomplete dominance over their more recessive allelic counterparts. In general, dominance is incomplete, with more color being dominant over less color.

        Besides expressing incomplete dominance, all spotting gene alleles are also affected by plus and minus modifying polygenes. In general, however, more color is believed dominant over less color. Because of the great variability in each of the four spotting gene alleles generally listed, the actual number of alleles possible at this locus currently can't be determined with certainty.

        The white spotting genes function by providing the "wrong" signal or interpreting the signal incorrectly. These altered signals affect the location and extent of white (unpigmented) areas.

        The following white spotting alleles, proposed by Little, are arranged in the descending order of dominance. (However, recent studies suggest that the arrangement by Little is overly simplistic and that there are at least three major genes (loci) needed to explain white spotting inheritance.)

      2. S - Dominant "S" (Self) Allele - Produces complete pigmentation. This allele is dominant and the no-spotting gene (doesn't allow spotting). An "SS" (solid-solid) Anatolian Shepherd may be completely solid or may have very minor white markings, such as a white spot on the chest, a white tail tip, or white on the toes. This is the normal gene in breeds without white markings.

      3. si- Irish spotting Allele (called Dutch Marked in Anatolian Shepherds)- Irish spotting creates a white collar and blaze with some white on the belly, legs and chest and white does not cross the back between the withers and the tail but may be on the back of the neck. This allele may be additive as dogs believed to be homozygous for Irish Spotting have irregular white patches on their bodies. The number and size of these patches is extremely variable.

      4. sp - Piebald spotting Allele (Pinto in Anatolian Shepherds) - codes for colored patches on a white background. The piebald allele results in well defined areas of colored and white hair. A piebald (pinto) has more than 50% of its body covered with white. The white often will cross the back and creates a pattern that appears as large colored spots on a white background.

      5. sw - Extreme White Piebald Allele (either Pinto or White in Anatolian Shepherds)- creates a few small colored spots on a white background. Coat color ranges from colored heads and a few colored spots on the body, especially near the tail, through dogs with color only around the eye or ear. Also, all white animals may be produced in some dog breeds, including Anatolian Shepherds.

      6. The Robison White Spotting Scale - An alternate white spotting theory - Roy Robison created a scale with ten types of spotting to help clarify the degree of spotting in individual dogs.

        White Spotting in horses has been extensively studied and is known to be caused by a variety of different gene loci rather than just one locus as proposed in dogs. Instead of just the one gene locus proposed by Little and later by Robison (above) for dogs, perhaps dogs possess several such white spotting gene loci.

        In more recent studies in Landseer dogs, this "one locus" view was suggested to be over-simplistic. These studies also speculated that at least three major genes are needed to explain the observed inheritance of white-spotting in dogs. For instance, there are white dogs with completely colored heads and solid colored dogs with half or all white heads. This kind of obvious deviation in head marking indicates that there is at least another gene affecting head markings.

        Because of our current, incomplete understanding of the genetic mechanism controlling white spotting, it is evident that further genetic research is required to more fully understand the genetic control mechanisms which produce white spotting.

    19. The "T" Gene Locus (Ticking Series): Controls the placement of black hairs in white areas of the coat

      1. Ticking appears as small spots of uniform color occurring in otherwise white areas of the coat. The term ticking does not include either the much larger sized true spots or roan, which is a random mixture of individual white and colored hairs (or perhaps roan is just and extreme expression of "T"). The color of the colored hair in the ticking is the color that the coat would have been in that area if the white spotting genes were not present.

        A sable (fawn in Anatolian Shepherds), especially one with very light phaeomelanin, may not have obvious ticking since the contrast between the tan and white may be faint. However, a close examination may reveal tan spots on the legs.

        Ticking is also more difficult to identify on long haired dogs. Ticking has been observed in Anatolian Shepherds but since light fawn (sable) is common, this genetic trait may frequently be overlooked without careful examination, which often reveals the flecks on the legs.

        Ticking has two identified alleles. However, some believe that more than two alleles may be involved and that ticking is greatly affected by genes which modify the size, shape, and density of tick marks.

      2. "T" - Ticking (an incompletely dominant gene)

      3. "tt" - wild type with lack of ticking (a recessive gene leaving the solid white spots free of colored hair)

    20. Polygenes
      1. General Information regarding Polygenes

        1. Polygenes are a set of gene alleles scattered over a number of different loci (rather than found only at one gene locus), and all working together to create a specific characteristic in the animal.

        2. Natural selection is more efficient and evolutionary changes can occur more rapidly when one gene locus controls a characteristic.

        3. A species is more likely to survive extreme environmental changes if that species is able to adapt by modifying its major characteristics rapidly. Therefore, essential characteristics of an organism are controlled by single-locus allele sets rather than polygenes.

        4. Less essential characteristics are controlled by polygenes (multi-loci gene alleles scattered over a number of different loci).

        5. An unknown number of color characteristics rely on polygenes, which take the form of plus or minus modifiers to alter the expression of a characteristic whose basic form was set by a major gene.

        6. The "S" Gene Locus (Spotting Series) is the most researched set of color polygenes in dogs. These polygenes vary the expression of S locus genes, which create varying amounts of white spotting on the dog. Ignoring the very rare albino and blue-eyed albino genes, there are usually four main genes listed at this locus, but Robinson has identified at least ten degrees of identifiable spotting. It is believed that adjustments are made to the main genes by modifying polygenes at a number of other loci, each of which can contain a "minus modifier" (which decreases spotting), or a "plus modifier" (which increases spotting).

        7. Anatolian Shepherds as a breed appear to have the full spectrum of spotting genes as well as the gene coding for solid color. With enough plus modifiers in an otherwise genetically solid colored dog, white areas can appear on feet, chest, tail tip, and perhaps elsewhere. With a sufficient number of plus modifiers, white can even look like the next level of spotting.

        8. Polygenes, including the ones that affect hip dysplasia, are difficult to eliminate from the genetic pool without a reliable genetic test. When two animals with many minus modifiers and few plus modifiers are mated, one or more of their offspring may get all of the plus modifiers. These "plus modifier" pups would be much more affected than either parent.

        9. Breeding rules are more reliable when all the genes affecting a characteristic are found at one locus than when the genes are polygenes.

      2. The rufus polygenes

      3. The rufus polygenes determine whether the coat is fawn or red or some shade in between. In addition to the major coat lightening genes, such as the chinchilla gene (c ch) in at the C gene locus (The Albino Series) mentioned above, there is a set of polygenes in which the combination of plus and minus modifiers makes the coat vary from paler yellow (light fawn) through deeper red (red). It is reported that on an individual gene basis the fawn may be dominant over the red. However, a dog with plus modifiers at a majority of the loci will be red (the more plus modifiers the deeper red the dog will appear). It is possible that only dogs without the chinchilla (cch) gene can reach the deep, dark red color rarely seen in Anatolian Shepherds.

      4. The umbrous polygenes

      5. The umbrous polygenes determine the extent of dark shading (black or brown pigment) present on a fawn background (red/yellow pigment). The type of light pigment present in many Anatolian Shepherds (from the influence of "AY," the "A" gene locus [The Agouti Series]) allows for the presence of sabling (dark tipped hairs) and sailing (longer black hairs on a fawn background). This dark shading varies from visually absent through very heavy shading. This variation in shading is attributed to the umbrous set of polygenes.

        Umbrous polygenes may have an effect on patterns such as brindling, black mask, or the saddle pattern, but these patterns probably have their own sets of polygenes. In fact, the saddle pattern seen on some dogs is speculated to be the result of polygenes alone. Also, it is speculated that polygenes affect the width, frequency, intensity, and evenness of brindle stripes. However, no research has been done on this aspect of coat color.

        Many additional sets of polygenes are thought to exist. However, since polygenes are more complex than the major genes, polygenes are difficult to research. Over time, perhaps we will learn more about the full extent of their influence.

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