OMIA:000296-9031 : Duplex comb in Gallus gallus (chicken)

Categories: Craniofacial phene

Links to possible relevant human trait(s) and/or gene(s) in OMIM: 604615 (gene)

Mendelian trait/disorder: yes

Mode of inheritance: Autosomal incomplete dominant

Considered a defect: no

Key variant known: yes

Year key variant first reported: 2015

Species-specific symbol: D

Mapping: The first data showing linkage of duplex comb to any other trait (in this case, polydactyly) were provided by Sererbrovsky and Petrov (1930). Duplex comb was allocated to a new (fifth) linkage group (group E) initially comprising duplex and multiple spurs (OMIA 000671-9031), by Hutt (1941), who was not aware of the results of Sererbrovsky and Petrov (1930). Additional data on this linkage group, including new loci, were provided by Warren (1941), and Hutt and Mueller (1943). The trait was included in Warren (1949)'s classic chicken linkage map. Dorshorst et al. (2010) were the first to physically map this trait, in the "33.6–39.8 Mb region of chromosome [GGA]2". Wragg et al. (2012) narrowed this location to 38.55–38.89 Mb on chromosome GGA2.

Molecular basis: In a landmark paper, Dorshorst et al. (2015) showed that "the two Duplex-comb alleles, V-shaped (D*V) and Buttercup (D*C), are both associated with a 20 Kb tandem duplication containing several conserved putative regulatory elements located 200 Kb upstream of the eomesodermin gene (EOMES). EOMES is a T-box transcription factor that is involved in mesoderm specification during gastrulation." The authors note that "The confinement of the ectopic expression of EOMES to the ectoderm is in stark contrast to the causal mechanisms underlying the two other major comb loci in the chicken (Rosecomb and Pea-comb) in which the transcription factors MNR2 and SOX5 are ectopically expressed strictly in the mesenchyme". Headon (2015) provides a very informative commentary on this discovery.

Associated gene:

Symbol Description Species Chr Location OMIA gene details page Other Links
EOMES eomesodermin Gallus gallus 2 NC_052533.1 (38507358..38502625) EOMES Homologene, Ensembl , NCBI gene


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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.

Since October 2021, OMIA includes a semiautomated lift-over pipeline to facilitate updates of genomic positions to a recent reference genome position. These changes to genomic positions are not always reflected in the ‘acknowledgements’ or ‘verbal description’ fields in this table.

OMIA Variant ID Breed(s) Variant Phenotype Gene Allele Type of Variant Source of Genetic Variant Reference Sequence Chr. g. or m. c. or n. p. Verbal Description EVA ID Year Published PubMed ID(s) Acknowledgements
759 Duplex comb EOMES duplication Naturally occurring variant 2 "a 20 Kb tandem duplication containing several conserved putative regulatory elements located 200 Kb upstream of the eomesodermin gene (EOMES)" 2015 25789773

Cite this entry

Nicholas, F. W., Tammen, I., & Sydney Informatics Hub. (2015). OMIA:000296-9031: Online Mendelian Inheritance in Animals (OMIA) [dataset].


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.

2015 Dorshorst, B., Harun-Or-Rashid, M., Bagherpoor, A.J., Rubin, C.J., Ashwell, C., Gourichon, D., Tixier-Boichard, M., Hallböök, F., Andersson, L. :
A genomic duplication is associated with ectopic eomesodermin expression in the embryonic chicken comb and two duplex-comb phenotypes. PLoS Genet 11:e1004947, 2015. Pubmed reference: 25789773. DOI: 10.1371/journal.pgen.1004947.
Headon, D. :
Morphological mutations: lessons from the cockscomb. PLoS Genet 11:e1004979, 2015. Pubmed reference: 25789884. DOI: 10.1371/journal.pgen.1004979.
2012 Wragg, D., Mwacharo, J.M., Alcalde, J.A., Hocking, P.M., Hanotte, O. :
Analysis of genome-wide structure, diversity and fine mapping of Mendelian traits in traditional and village chickens. Heredity (Edinb) 109:6-18, 2012. Pubmed reference: 22395157. DOI: 10.1038/hdy.2012.9.
2010 Dorshorst, B., Okimoto, R., Ashwell, C. :
Genomic regions associated with dermal hyperpigmentation, polydactyly and other morphological traits in the Silkie chicken. J Hered 101:339-50, 2010. Pubmed reference: 20064842. DOI: 10.1093/jhered/esp120.
1993 Shoffner, R.N., Otis, J.S., Garwood, V.A. :
Association of dominant marker traits and metric traits in chickens. Poultry Science 72:1405-1410, 1993. Pubmed reference: 8378215.
1991 Somes, R.G. :
Some observations on high cavernous nostrils in the chicken. J Hered 82:172-4, 1991. Pubmed reference: 2013692. DOI: 10.1093/oxfordjournals.jhered.a111055.
Somes, R.G. :
Duplex Comb in the Chicken - A Multi-Allelic Trait Journal of Heredity 82:169-172, 1991. Pubmed reference: 2013691.
1949 Warren, DC. :
Linkage relations of autosomal factors in the fowl. Genetics 34:333-50, 1949. Pubmed reference: 17247319.
1943 Hutt, F.B., Mueller, C.D. :
The linkage of polydactyly with multiple spurs and duplex comb in the fowl American Naturalist 77:70, 1943.
1941 Hutt, F.B. :
Genetics of the fowl. 15. Multiple spurs, a mutation linked with duplex comb. Journal of Heredity 32:357-364, 1941.
Warren, D.C. :
New type of polydactylism in the fowl. Journal of Heredity 32:2-5, 1941.
1930 Serebrovsky, A.S., Petrov, S.G. :
[On the composition of the plan of the chromosomes of the domestic fowl] translated by B.F. Glessing. U.S. Dept. Agric. Journal of Experimental Biology (Russian) 6:157-179, 1930.
1923 Punnett, R.C. :
Heredity in Poultry London: Macmillan & Co. , 1923.
1600 Aldrovandi, U. :
Ornithologiae tomus alter cum indice copiosissimo. Bologna , 1600.

Edit History

  • Created by Frank Nicholas on 06 Sep 2005
  • Changed by Frank Nicholas on 01 Jul 2012
  • Changed by Frank Nicholas on 06 Jul 2012
  • Changed by Frank Nicholas on 18 Aug 2013
  • Changed by Frank Nicholas on 21 Mar 2015
  • Changed by Frank Nicholas on 23 Mar 2015