
Testing of dogs: Locus EG
Locus EG
The allele EG is responsible for the grizzle coloration in Saluki breed and domino colour in Afghan Hounds. A mutation in the MC1R-gene occurs (c.233G>T) in both breeds. The phenotype connected with this mutation is light hair on the face and eyebrows.
The mutant EG-allele is dominant over E and e alleles but recessive to the EM allele. The expression of EG allele is influenced particularly by A-locus. The grizzle and domino colours occur only in dogs possessing two at alleles. If a dog carries one or two ay alleles, the grizzle or domino colours will remain hidden. The expression of this colour in puppies within the litter will depend mainly on the fact whether one parent dog has one or two EG alleles and its partner the at allele in its genotype. Further, a complicating factor is the presence of EM that cancels the effect of the EG allele.
Locus E hierarchy is as follows: EM> EG> E> EH> e. To determine the final locus E genotype, it is necessary to test all locus E alleles. This test only detects the presence or absence of EG allele.
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Rules of inheritance of grizzle and domino coloration:
- Grizzle or domino colour can only occur in dogs that have at least one EG allele and two at alleles; an exception is situation when the EG allele is not expressed due its combination with the EM allele which suppresses the effect of EG allele
- If a dog carries at least one EG allele and only one at allele, the grizzle or domino colour will not express, but can be passed on to offsprings and expressed in a later generation
- If a dog carries at least one EG allele and two ayalleles, the grizzle or domino coloration will not be expressed and will be only passed on to next generations.
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1. Possible genotypes - Saluki
Example of Saluki in grizzle color:
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Genotype |
Colour |
Carrier of colour |
|
EG/EG |
at/ at |
grizzle |
eumelanin-and-tan |
EG/E |
at/ at |
grizzle |
eumelanin-and-tan |
EG/e |
at/ at |
grizzle |
red, eumelanin-and-tan |
EM/EG |
at/ at |
eumelanin-and-tan, with mask |
grizzle, eumelanin-and-tan, with mask |
EM/EG |
ay/ ay |
red or cream with mask |
grizzle |
EG/EG |
ay/ ay |
red or cream |
grizzle |
EG/E |
ay/ ay |
red or cream |
grizzle |
EG/e |
ay/ ay |
red or cream |
grizzle,red |
EM/EG |
ay/ at |
red or cream, with mask |
grizzle, eumelanin-and-tan |
EG/EG |
ay/ at |
red or cream |
grizzle, eumelanin-and-tan |
EG/E |
ay/ at |
red or cream |
grizzle, eumelanin-and-tan |
EG/e |
ay/ at |
red or cream |
red, grizzle, eumelanin-and-tan |
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2. Possible genotypes – Afghan hound
Example of Afghan hound in domino color:
.
Genotype |
Colour |
Carrier of colour |
|
EG/EG |
at/at |
domino |
black and tan, with mask |
EG/E |
at/at |
domino |
black and tan, with mask |
EG/e |
at/at |
domino |
red, black and tan, with mask |
EM/EG |
at/at |
black and tan, with mask |
domino, black and tan, with mask |
EM/EG |
ay/ay |
red or cream |
domino |
EG/EG |
ay/ay |
red or cream |
domino |
EG/E |
ay/ay |
red or cream |
domino |
EG/e |
ay/ay |
red or cream |
domino, red |
EM/EG |
ay/at |
red or cream |
domino, black and tan, with mask |
EG/EG |
ay/at |
red or cream |
domino, black and tan, with mask |
EG/E |
ay/at |
red or cream |
domino, black and tan, with mask |
EG/e |
ay/at |
red or cream |
red, domino, black and tan, with mask |
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Citace:
Dreger, D. L., & Schmutz, S. M. (2010). A new mutation in MC1R explains a coat color phenotype in 2 “old” breeds: Saluki and Afghan hound. Journal of Heredity, 101(5), 644-649.