OMIA 001972-9793 : Coat colour, dun in Equus asinus

In other species: horse

Mendelian trait/disorder: yes

Mode of inheritance: Autosomal Dominant

Considered a defect: no

Key variant known: yes

Year key variant first reported: 2020

History: Wang et al. (2020): "Coat color is one of the main traits that were selected during the domestication process. The base color of donkeys can be black or red (chestnut) [Sponenberg, 2009]. There is a dominant Dun allele causing strong dilution of the pigmentation, which becomes gray or light chestnut/rose Dun, in contrast to the recessive non-Dun allele (black or chestnut, as mentioned previously). The Dun coat is considered to be the ancestral wild type [Groves, 1986], while the non-Dun coat is found exclusively in domestic animals."

Mapping: Wang et al. (2020) "de novo assembled a chromosome-level reference genome of one male Dezhou donkey and analyzed the genomes of 126 domestic donkeys and seven wild asses. ... Photos and records were used to determine the coat color of 44 donkeys, which were divided into two groups, i.e., Dun (23 gray donkeys) and non-Dun (21 black donkeys). In the two compared groups (Dun vs. non-Dun), we calculated π and Tajima’s D in the major selective sweep mapping to chromosome 8 (~ 42.6 Mb)."

Molecular basis: Wang et al. (2020) "found only one indel CT/C− located at chr8:42,742,556 (CT was the genotype of the reference genome), which segregated perfectly with the non-Dun phenotype. ... the non-Dun phenotype is caused by a 1 bp deletion downstream of the TBX3 gene, which decreases the expression of this gene and its inhibitory effect on pigment deposition. .... The alignment of sequences containing the non-Dun1 allele of horse with the donkey sequence that harbors the 1 bp deletion mentioned previously indicated that these sequences are homologous."

Associated gene:

Symbol Description Species Chr Location OMIA gene details page Other Links
TBX3 T-box 3 Equus asinus - no genomic information (-..-) TBX3 Homologene, Ensembl, NCBI gene


By default, variants are sorted chronologically by year of publication, to provide a historical perspective. Readers can re-sort on any column by clicking on the column header. Click it again to sort in a descending order. To create a multiple-field sort, hold down Shift while clicking on the second, third etc relevant column headers.

WARNING! Inclusion of a variant in this table does not automatically mean that it should be used for DNA testing. Anyone contemplating the use of any of these variants for DNA testing should examine critically the relevant evidence (especially in breeds other than the breed in which the variant was first described). If it is decided to proceed, the location and orientation of the variant sequence should be checked very carefully.

Breed(s) Variant Phenotype Gene Allele Type of Variant Reference Sequence Chr. g. or m. c. or n. p. Verbal Description EVA ID Year Published PubMed ID(s) Acknowledgements
Non-dun TBX3 deletion, small (<=20) 8 g.42742557delT "This 1 bp deletion (chr8:g.42742556 CT>C−) is located ~18.6 kb downstream of the transcription start site of the TBX3 gene." (Wang et al., 2020) 2020 32948208


Note: the references are listed in reverse chronological order (from the most recent year to the earliest year), and alphabetically by first author within a year.
2020 Wang, C., Li, H., Guo, Y., Huang, J., Sun, Y., Min, J., Wang, J., Fang, X., Zhao, Z., Wang, S., Zhang, Y., Liu, Q., Jiang, Q., Wang, X., Guo, Y., Yang, C., Wang, Y., Tian, F., Zhuang, G., Fan, Y., Gao, Q., Li, Y., Ju, Z., Li, J., Li, R., Hou, M., Yang, G., Liu, G., Liu, W., Guo, J., Pan, S., Fan, G., Zhang, W., Zhang, R., Yu, J., Zhang, X., Yin, Q., Ji, C., Jin, Y., Yue, G., Liu, M., Xu, J., Liu, S., Jordana, J., Noce, A., Amills, M., Wu, D.D., Li, S., Zhou, X., Zhong, J., Jost, S.M., Knoll, A., Lühken, G., Drögemüller, C., Zanolari, P. :
Prevalence of coat colour traits and congenital disorders of South American camelids in Austria, Germany and Switzerland. Acta Vet Scand 62:56, 2020. Pubmed reference: 32948208. DOI: 10.1186/s13028-020-00554-y.
2009 Sponenberg, D. P. :
Equine Color Genetics, Wiley-Blackwell; 3rd edition :, 2009.
1986 Groves, C.P. :
The taxonomy, distribution and adaptations of recent equids. in 'Equids in the Ancient World' (R. H. Meadow and H. P. Uerpmann, eds.), Dr. Ludwig Reichert Verlag, Wiesbaden. :11-65, 1986.

Edit History

  • Created by Imke Tammen2 on 17 Dec 2020
  • Changed by Imke Tammen2 on 17 Dec 2020