In the spring of 2015, the American Simmental Association had a report of a red calf confirmed to a tested homozygous black bull. While learning about this case, several sons of Remington Lock N Load, 2503661, appeared to carry a red coat color variant not recognized by the existing coat color test. These bulls all tested homozygous black but sired red calves. The American Simmental Association started researching this further with Dr. Clare Gill from Texas A&M. A similar scenario was originally reported to Dr. Gill in a bull named SV Red Charlie, 1680096. At the time SV Red Charlie was reported, there weren't enough samples to draw any conclusions. With additional samples, Dr. Gill discovered a mutation in the main coat color gene, MC1R. This mutation was not detected with the current coat color test but would result in the equivalent of a red allele.
The new variant, dubbed Red Charlie, causes a loss of function of the MC1R gene – similar to the existing red allele. The inheritance and functionality of the Red Charlie variant are the same as the existing red coat color allele. Red Charlie is linked only to the black allele; in other words, it is not found in conjunction with the red or the wild type alleles (the other two options for MC1R).
GeneSeek validated the Red Charlie marker and launched the new red coat variant test for it in summer 2016. Breeders interested in coat color testing on a Red Charlie suspect animal need to order both the regular coat color test and the Red Charlie test to have a complete picture of the animal's genotype for coat color. Animals that test homozygous black and carry the Red Charlie allele should be treated like a heterozygous black animal. In ASA’s Herdbook database, the main animal page will combine both the coat color and the Red Charlie tests/pedigree risks to indicate if the animal is homozygous or heterozygous black. The TraitTrac page will show the coat color and the Red Charlie results independently.
These screen shots show an example of a Red Charlie Carrier display in the main animal page and in TraitTrac in Herdbook services. Note the main animal page lists the animal as “heterozygous black” under the name. If the “Check Available Results” text is clicked, breeders can view the TraitTrac page for that animal. Here, each test is displayed independently. This animal tested homozygous black (“TF” for the Coat Color red and the wild type alleles) but a carrier for the Coat Color — Red Charlie test (TC). If an animal is a potential carrier of Red Charlie (carrier in the lineage), the main page will not display “homozygous black” until the Red Charlie is tested even if the traditional coat color testing is completed.
Take Home Messages:
- Red Charlie inheritance and function is exactly like the traditional red coat color allele. In other words, a Red Charlie carrier is exactly like an animal with one black allele and one red allele (heterozygous black). If two Red Charlie carriers are mated, 25% of the calves will be truly homozygous black (and appear black), 50% will be heterozygous black (and appear black), and 25% will be homozygous red (and appear red).
- Tested homozygous black animals with a Red Charlie carrier in the lineage are potentially heterozygous black animals.
- Breeders may receive coat color tests that say homozygous black and will need to look at the Red Charlie test/pedigree risk to truly know if the animal is homozygous black.
- Red Charlie will need to be ordered in addition to the coat color test and will have additional costs and reports.
Information current as of February 2019.
- Category: Simply-Inherited Trait
- Created: 13 May 2016