Intro to Gene Loci for Rat Coat Color

AFRMA will be used as a primary source including the book from AFRMA “Rat Genetic 4th Edition, 2012”                                                                                         

http://www.afrma.org/

http://www.afrma.org/ratgenpart1.htm

http://www.afrma.org/sales/afrmabks.htm (where books can be purchased on breeding and genetics)

http://ratvarieties.com/

1. Introduction
1. Two basic pigments eumelanin: (black/brown) and phaeomelanin (yellow/red)

2. Agouti Locus (A or a), Asip (agouti signaling protein)
1. With the dominant allele, hairs will have bands on yellow pigment near the top
2. The agouti color is defined by three bands of color yellow, black and brown
3. Alleles at other loci can produce many varieties in coat color
1. AA or Aa
1. agouti, blue agouti, fawn, silver fawn, lynx, chinchilla, cinnamon, cinnamon pearl, and pink eyed white (albino)
2. Non-agouti aa
1. black group: black, beige, champagne, pale champagne, and chocolate
2. blue group: blue, sky blue, powder blue, silver, and platinum
3. russian blue group: russian blue, blue-beige, dove, silver platinum/ russian dove, silver blue
4. siamese group: seal point siamese, blue point siamese, russian blue point siamese, himalayan, and pink eyed white (albino)
5. Pearl, mink/lilac, merle group: pearl, mink, silver mink, lilac, silver lilac, pale champagne, dark eyed champagne, perle merle

3. Albino Locus (C, cch, cd, ch, c, cm), Tyr (tyrosinase)
1. Causes dilution of yellow and black pigment
2. cc produces the albino pink eyed white (PEW)
3. chch eliminates yellow pigment and dilutes black pigment to brown. In addition it causes acromelanism where cooler parts of the body, i.e. the extremities show darker pigment and phenotypically produces the siamese pattern.
1. The color of the siamese can be altered by genes at other loci
2. The heterozygoous cch is the lighter himalayan variety
4. Cm creates the Marten rat also known as the “red eyed devil. It is a red eyed rat homoygous for the non-agouti gene. It is a grey with heathering. If the agouti gene is present the rat will be a silver agouti appearing grey with brown and yellow undertones.
5. http://docs.wixstatic.com/ugd/93ab82_879058cbf7d74679892f1dfe101c9c97.pdf
6. http://sodapoprats.weebly.com/about-c-locus.html

4. Brown Locus (B, b)
1. Determines if eumelanin is black or brown
2. The dominant allele selects for black and the recessive for brown
3. bb results in the chocolate phenotype
4. When paired with the agouti gene the result is dark cinnamon and considered not show quality
5. When paired with the blue gene they are a silver color called platinum

5. Pink Eyed Locus (P, p)
1. Dilutes eye color and eumelanin creating pink eyes and a pale yellow color
2. Rats homozygous for non-agouti gene (black, chocolate, lilac, and mink) are diluted to shades of champagne.
1. If the rat is also homozygous for the blue gene i will be a blue tinted white called silver
3. Agouti rats, AA or Aa, are diluted to silver fawn and amber (a lighter shade of silver fawn)

6. Red Eyed Locus (R, r), Rab38 (Ruby)
1. Dilutes eyes to a ruby color
2. Agouti rats, Aa or AA, are diluted to fawn (NFRS topaz)
3. Black animals are diluted to beige (NFRS buff)

7. Mink Locus (M, m)
1. Dilutes black to gray-brown
2. Agouti rats, Aa or AA, are diluted to cinnamon
3. Homozygous non-agouti animals are diluted to mink or the lighter shade lilac

8. Pearl Locus (Pe, pe)
1. Only affects the expression of the mink locus, causing base of hair to be white with tip retaining color.
2. The pearl mutation is both dominant and homozygous lethal. An agouti and mink rat is cinnamon pearl.
3. Rats homozygous for non-agouti and mink are pearl.

9. Dilute Locus (D, d)
1. DIlutes black, rats homozygous for non-agouti, to a bluish grey color known as the American blue.
2. 
   
10. Russian Blue Locus
1. Creates a non-agouti animal similar to the American blue but with a deeper shade of grey and lightly pigmented ears.

11. Epistatic Gene Combinations
1. Apricot agouti is an agouti rat homozygous for the blue dilute gene and the pink eyed dilution gene i.e. A_ddpp
2. Cocoa (NFRS coffee) is a rat homozygous for non-agouti and homozygous for both mink and chocolate alleles i.e. aabbmm