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Glossary of Genetic Terms

   
Cobain CGN

Don't Litter,- Spay and Neuter		 
 
Barked: Wed Jul 30, '08 1:47pm PST 
I thought this would help some new comers make sense of some of the wording here. Also I've added some terminology used when classifying dog coat colours
Feel free to add more smile

Belton a name for ticking in the English Setter
Bicolor a dog that has some shade of black or brown and also white but no tan in breeds like the Shetland Sheepdog
Blenheim a name for red coat color with white markings in the Cavalier King Charles Spaniel
Blue a coat color that is typically a solid grey (note that a Blue Belton is a black ticked/roan dog however)
Brindle a pattern of alternating stripes of eumelanin and phaeomelanin pigmentation, i.e. yellow and black, red and black, cream and grey, etc.
Chocolate a coat color that is typically brown, used in breeds such as the Labrador Retriever
Dilution an effect on a coat color that causes it to become a paler shade like blue or cream
Eumelanin a melanin pigment that causes some shade of black or brown coloration
Harlequin a coat color pattern of ragged black spots on a white background in the Great Dane
Irish Spotting a pattern of white markings that include white undersides, a white blaze and usually a white collar
Liver a coat color that is typically brown but is occasionally used to describe a shade of orange or phaeomelanin pigmentation
Mask a pattern in which the muzzle and perhaps as far back as the ears are pigmented by eumelanin, resulting in a black or brown face
Merle a pattern which reminds one of marble in which the melanin pigment is swirled and patchy amongst many white areas
Phaeomelanin a melanin pigment that causes some shade of red, orange, gold or yellow coloration
Piebald random spots of color on a white background
Red a coat color that is typically the result of phaeomelanin pigmentation, however in some breeds such as Doberman Pinschers brown is called red
Roan a pattern of intermingled white and colored hairs on some part of the body
Ticked a pattern of many small pigmented spots on a white or roan background
Tricolor a combination of some shade of black or brown, some shade of red often called tan and some white. Therefore both eumelanin and phaeomelanin pigmentation occurs on the same dog.
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Gio

CD RE (CKC) RACL- (CARO) FM CGN- SJATD HIC
 
 
Barked: Thu Jul 31, '08 11:43am PST 
I'll also add a couple of definitions for words that I find myself using often.

Gene = A particular area of the chromosome that codes for a protein. In the case of coat color genetics, the protein then interacts with other proteins, environment, enzymes, regulators, etc. and results in a particular coat color pattern.

Mutation = Each gene is made up of a particular code of molecules. Each molecule is given a letter, either A, T, G, or C. These four letters arrange themselves in patterns making each gene unique from the others. If there is ever a "mistake" in the code, that counts as a mutation.

Phenotype = The result of particular gene coding that we SEE. For instance, blonde hair is a phenotype. Or blue eyes, or freckles, or long legs.

Allele = Mutations do not always result in lethal outcomes. Instead, some mutations make minute alterations to a gene that makes it behave in a different way, changing what we "see" as an outcome. A particular mutation that results in a different phenotype is called an allele. A gene can have only one allele, ie. no mutations, or multiple alleles resulting in numerous possible phenotypes.

Genotype = The particular alleles at a given gene.

Dominant = Some mutations result in alleles that are always expressed when they are present, these are called dominant.

Recessive = Some mutations result in alleles that are only expressed if there are no other more dominant alleles, these are celled recessive.

Here is an example.

There is a gene called Melanocortin Receptor 1 (abbreviated as MC1R). This gene has 2 different mutations that are possible in addition to the possibility of NO mutation. These two mutations and one non-mutation (wild type) result in three alleles, in this case, EM, E, and e (where E is the wild type). Each individual dog has two copies of every gene, and each gene can be of a different allele. As such, with three alleles there are 6 different possible combinations: EM/EM, EM/E, EM/e, E/E, E/e, e/e. Each combination is called the genotype. Even though there are 6 different genotypes that are possible, there are only 3 different phenotypes, mask (EM/EM, EM/E, EM/e), no mask (E/E, E/e) or red (e/e) with the possible phenotypes being mask, no mask, and red.
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