Dominant White and White Spotting

Quick Summary

White spotting patterns occur in many donkey breeds and are similar to those of horses in that the amount of white can range from a few white hairs to an animal that is almost completely white.

Spotted Donkey
White spotting pattern on a donkey

Phenotype: White spotting patterns occur in many donkey breeds; as in horses, the amount of white can range from a few white hairs to an animal that is almost completely white.

Mode of Inheritance: Autosomal dominant

Alleles: N = Normal, W = Dominant White, WS = White Spotted

Breeds appropriate for testing: Many breeds including American Miniature and Mammoth Jack

Explanation of Results:

  • Donkeys with N/N genotype are not expected to have white coats or white spotting patterns (but there may be other unidentified variants not detected by this test that cause some white patterning). Donkeys with this N/N genotype cannot transmit either of these white variants to their offspring.
  • Donkeys with N/W genotype are expected to be white. They will transmit this dominant white variant to 50% of their offspring.
  • Donkeys with W/Ws genotype are expected to be white. They will transmit this dominant white variant to 50% of their offspring and this white spotted variant to 50% of their offspring.
  • Donkeys with N/Ws genotype are expected to be white spotted. They will transmit this white spotted variant to 50% of their offspring.
  • Donkeys with W/W genotype are are expected to terminate development in utero (embryonic lethal) or be non-viable.
  • Donkeys with Ws/Ws genotype will be white and are expected to be incompatible with life.
Price

$25 one test per animal
$40 two tests per animal
$60 three tests per animal

Panels Available
Additional Details

Donkey with white spots
White spotting pattern on a donkey

White spotting patterns occur in many donkey breeds and are similar to those of horses in that the amount of white can range from a few white hairs to an animal that is almost completely white. Two mutations in the KIT gene have been identified that cause white spotting in donkeys, and they have been named dominant white (W) and white spotted (Ws). Both are inherited in an autosomal dominant fashion, meaning that only one copy of either mutation is required to produce white pattern phenotypes. The genetic basis for the variability in the amount of white is not known.

Homozygosity for the Ws allele is thought to be incompatible with life, and the VGL's testing of one Ws/Ws foal who died by 2 weeks of age suggests that this may indeed be the case. The W allele has only been identified in a single individual born with an all-white phenotype. It is unlikely that a W/W donkey would be born and viable. Lethality of W and Ws mutations remains to be confirmed.

Genetic testing is recommended for all donkey breeds known to have a white spotting phenotype. Breeders can benefit from this test to determine which mutation is present in a white patterned donkey and also to select mating pairs to avoid breeding two white patterned donkeys together, as such matings may result in inviable foals.

Turnaround Time
5-10 business days
Type of Sample

Species

Type of Test

Results Reported As
Result Dominant White and White Spotting
N/N Normal. No copies of the identified dominant white or white spotted mutations.
N/W 1 copy of the dominant white mutation. Donkey is white.
W/W 2 copies of the dominant white mutation. Predicted to be lethal in utero.
N/Ws 1 copy of white spotted allele. Donkey is white spotted.
W/Ws 1 copy of the dominant white mutation and 1 copy of white spotted. Donkey is predicted to be white.
Ws/Ws 2 copies of the white spotted mutation. Color is white. Predicted to be lethal.
References

Haase, B., Rieder, S., & Leeb, T. (2015). Two variants in the KIT gene as candidate causative mutations for a dominant white and a white spotting phenotype in the donkey. Animal Genetics, 46(3), 321-324. doi: 10.1111/age.12282

Fenn, D.J., Raudesepp, T., Cothran, E.J., Hamilton, N.A., & Haase, B. (2016). Validation of a candidate causative mutation for white spotting in donkeys. Animal Genetics, 48, 124-125. doi: 10.1111/age.12494