What makes what and how?!
K-Locus, also called the dominant black locus. Making Fawn and Brindle French bulldogs
If a dog is brindle it is determined at the K Locus(location). Two sets of Genes can be held here at this location, ‘Ky” and “Kbr”. The “Kbr” gene, also known as the brindle gene, is dominant over the “ky” gene. If a dog carries one copy of brindle it is showed as (kbr/ky) in the K-Locus or two copies(kbr/kbr). If the dog have 1 or 2 copies of the brindle gene the dog will express a brindle coat. The “Ky” gene, its known as the allowing gene. This is because when 2 copies are present it allows the A-Locus, the D-locus and B-locus to determine the dogs coat over all pattern. The “Kbr” brindle gene interferes with the color expression of the A,D and B-locus giving you the brindle look
A-Locus. Solid Black, Tri-color, Fawn and sable Locus gene here.
Boy is this Locus crowded! The four genes held at this location are “Ay” for Fawn, “At” the tan and point or Tri-color gene, “a” the solid black gene and “aw” for sable. “Ay” and “Aw” are very similar and are dominant over, “At” and “a”, making it so the tan and point or Tri-color gene “At” and the black gene “a” are not noticeable in the dog. “At” is dominant over “a”, so if a dog is (At/a) at this Locus the dog will show the same markings as a dog that’s (At/At). If a dog is (Ay/At)(Aw/At)(Aw/a) or (Ay/a) the dog will be fawn or sable not showing the traits from the tan and point gene of the solid black gene. A Dog will only be full solid black if its carries two copies of the “a” gene (a/a). A dog who’s brindle (kbr/kbr)( kbr/ky) will be brindle expressing itself over the A location. If a dog is (At/At) or (At/a) the brindling will be expressed where the tan points should be. If a dog is (Ay/At)(Aw/At)(Ay/a) or ( Aw/a) and carries 1 or 2 brindle genes the brindle will be expressed all over the dog. If a dog is (a/a) and carries 1 or 2 brindle gene the brindle is not expressed because since (a/a) is solid black and brindle is black that allows some fawn to come though there is no fawn to let though so the brindle is not noticed. If the dog is Ky/Ky not carrying a brindle gene it allows all genes in the Alocation to be expressed with our any interference.
D-Locus. Blue French Bulldogs
The blue Locus seems to be everyone’s favorite. A fun fact about the D-Locus is actually just a dilute gene. It dilutes(waters down) the colors that the dogs are in the K-Locus and A-locus. If a dog is solid black with 2 blue dilutes its becomes a solid blue dog! If the dog is a Fawn dog with 2 blue dilutes it becomes a Blue Fawn, champagne color.
B-Locus. Chocolate French Bulldogs
This Locus work similarly as the D-locus. It is a recessive so 2 copies of the Chocolate Allele is needed for the chocolate color to be expressed. At this stage of color testing in dogs they have yet to develop a test to confirm if dogs carry chocolate or not. The only way to truly confirm if a dog carries it is if you breed it to a dog that is chocolate or carries chocolate and you get some chocolate puppies as an outcome.
There is also a different shade of chocolate that looks totally different then the original chocolate that has been introduced over the years. They are calling testable chocolate because it can be tested.
E-Locus. Cream French Bulldogs.
This Locus is called the Reverse yellow Locus but we know it as Cream : ) Cream is the most dominant gene is the Frenchie color pool if 2 copies are present in the Locus “e/e”. If a dog carries two copies of cream at the E-locus (e/e) the dog will be completely covered in cream no matter what color or pattern the dog carries. In most cases if a dog carries one copy of the cream gene (E/e) a slightly lighter coat can be noticed on whatever dominant color the dogs coat is. So, for example is a dog is Blue(d/d) and carries one copy of cream so its (d/d E/e) the dog will appear at times a little lighter blue compared to a dog that carries no cream. If a dog carries 2 copies of cream on a blue dog so it’s (d/d)(e/e), the dog will be completely covered in cream.
Tri Color French Bulldogs
These are my personal favorite. There are many Tri color variations; Black and Tan, Chocolate and Tan, Blue and Tan, Lilac and Tan and Merle and Tans. What gives these dogs tan point markings is the Allele combination at the A-Locus. The “At” gene is the main component in giving the dog its tri-color appearance. As mentioned before the At gene is dominant over the “a” gene. So if a dog is (At/At) or (At/a) at the A-locus the dog will express its Tan Points. Apart from the dogs tan points what gives your dog its coat color is what Alleles your dogs carry at the D-Locus, B-Locus and M-Locus. The coat of a tri color dog that doesn’t carry 2 alleles of blue or chocolate base color is solid black.
Lilac French Bulldogs
This color is a combination of the D-locus(Blue) and the B-locus(chocolate) when 2 copies of each Allele are present at each Locus (d/d)(b/b). The coat will usually have a purplish color if the dog carries one or 2 copies of the “KBR”gene or be solid purple is the dog also is solid black to Tri color. (a/a)(at/a)(at/at). IF the dog isn’t Tri color, solid black (a/a) or carry the brindle gene the dog will be a lilac Fawn having a more yellowish champagne look towards it apposed to a blue fawn what would look snowier champagne
M-Locus Merle French bulldogs
The Merle gene is held at the M-Locus. A dog only needs to carry one copy of the Merle gene for it to be dominant and expressed on the French Bulldogs coat. It is not like the blue, chocolate, or cream Locus that need 2 copies the dilute for it to be expressed. So if a dog is blue and carries one copy of merle the dog will be a blue merle with merle pattern shown all over the French Bulldogs coat blue coat. When a dog is tan and point so (At/at) or( At/a) and carries no brindle gene the tan points are 100% visible on a merle dog. The Merle genes is lot more visible on a dog that has a dark coat such as brindle dogs (kbr/ky) or dogs that are tri color(at/at)(at/a) or solid black(a/a).
The piebald gene is held at the S-Locus. It is a recessive gene so it needs 2 copies for the piebald to be expressed in the dog. For dogs that are dominate in Pied it is written as S/S. For dogs that are carriers of Pied it is written n/S. For dogs that are negative in Pied it is written as n/n.