| Other Names: | Roan, Ticking |
|---|---|
| Affected Genes: | USH2A |
| Mutation(s): | R = chr38:11834953 (CanFam4) C/T; RTi = chr38:11848131 (CanFam 4) T/C |
| Breed(s): | All breeds |
Testing Summary
The Paw Print Genetics R Locus (Roan/Ticked) evaluates two markers, one linked to Roan and one linked to Ticking. The R Locus coat color test reliably determines if a dog has one of the following genotypes at the R locus:
| r/r | This dog does not carry a copy of R or RTi and has a genotype of r/r which does not result in roan or ticking in the white areas of the coat. This dog will pass one copy of r to 100% of its offspring. Interpretation: No Roan or ticking |
| R/r | This dog carries one copy of R and one copy of r which results in roan in the white portions of the coat. However, the dog’s coat color is also dependent on the dog’s genotypes at the S, E, K, A, and B genes among others. This dog will pass one copy of R to 50% of its offspring and one copy of r to 50% of its offspring. Interpretation: Roan (carries non-roan) |
| R/R | This dog carries two copies of R which results in roan in the white portions of the coat. However, the dog’s coat color is also dependent on the dog’s genotypes at the S, E, K, A, and B genes among others. This dog will pass one copy of R to 100% of its offspring. Interpretation: Roan |
| RTi/r | This dog carries one copy of RTi and one copy of r which results in ticking in the white portions of the coat. However, the dog’s coat color is also dependent on the dog’s genotypes at the S, E, K, A, and B genes among others. This dog will pass one copy of RTi to 50% of its offspring and one copy of r to 50% of its offspring. Interpretation: Ticked (carries non-roan) |
| RTi/RTi | This dog carries two copies of RTi which results in ticking in the white portions of the coat. However, the dog’s coat color is also dependent on the dog’s genotypes at the S, E, K, A, and B genes among others. This dog will pass one copy of RTi to 100% of its offspring. Interpretation: Ticked |
| R/RTi | This dog carries one copy of R and one copy of RTi which results in roan in the white portions of the coat. However, the dog’s coat color is also dependent on the dog’s genotypes at the S, E, K, A, and B genes among others. This dog will pass one copy of R to 50% of its offspring and one copy of RTi to 50% of its offspring. Interpretation: Roan (carries ticking) |
Detailed Summary
Coat patterns of Roan and Ticking are pigmented hairs dispersed among areas of white. Puppies are born with a clear white coat and develop the Roan or Ticking pattern within the first weeks of life. Roan is characterized by a diffuse pattern of pigmented and white hairs; whereas Ticking is more regular shaped spots on the white part of the coat and seen primarily on the muzzle and legs.
The patterning in Dalmatians is a combination of Roan and another, unknown Locus.
Testing Tips
The linked marker for Roan is near the duplication that is thought to be the cause of Roan. There is the possibility of this marker being ‘unlinked’ to the Roan Mutation and would cause the dogs genotype to not reflect the actual status of Roan.
The dog’s coat color is also dependent on the dog’s genotypes at the S, E, K, A, and B genes among others. Normal results do not exclude inherited mutations not tested in these or other genes that may also contribute to coat colors and traits in dogs. Reliable genetic testing is important for determining breeding practices. NOTE: Roan and Ticked are only seen in the white portions of the coat; if a dog does not have white (eg. Parti or piebald), then the Roan and Ticked will not be visible.
There may be other causes of this color pattern in dogs and a normal result does not exclude a different mutation in this gene or any other gene that may result in a similar genetic trait.
References
- Brancalion L, Haase B, Mazrier H, Willet CE, Lindblad-Toh K, Lingaas F, Wade CM. Roan, ticked and clear coat patterns in the canine are associated with three haplotypes near usherin on CFA38. Anim Genet. 2021 Apr;52(2):198-207. [PubMed: 33539602]
- Kawakami T, Jensen MK, Slavney A, Deane PE, Milano A, Raghavan V, et al. (2021) R-locus for roaned coat is associated with a tandem duplication in an intronic region of USH2A in dogs and also contributes to Dalmatian spotting. PLoS ONE 16(3): e0248233. https://doi.org/10.1371/journal.pone.0248233
- Kawakami T, Jensen MK, Slavney A, Deane PE, Milano A, Raghavan V, Ford B, Chu ET, Sams AJ, Boyko AR. R-locus for roaned coat is associated with a tandem duplication in an intronic region of USH2A in dogs and also contributes to Dalmatian spotting. PLoS One. 2021 Mar 23;16(3). [PubMed: 33755696]
