OMIA 000884-9031 : Rose comb in Gallus gallus

Mendelian trait/disorder: yes

Mode of inheritance: Autosomal Dominant

Considered a defect: yes

Key variant known: yes

Year key variant first reported: 2012

Species-specific symbol: R

History: This trait is one of the first six animal traits to be shown to be inherited in a Mendelian manner, in adjacent papers by Bateson (1902) and Bateson and Saunders (1902). The other five traits are Pea-comb (OMIA 000782-9031), Polydactyly (OMIA 000810-9031), Dominant White (OMIA 000373-9031), and Yellow skin (OMIA 001449-9031) in chickens; and polled (OMIA 000483-9913) in cattle.

This trait was also one of the first pair of loci in farm animals to be shown to be linked autosomally, when Serebrovsky and Petrov (1928) reported a recombination fraction of 8% between this locus and Creeper (OMIA 000006-9031). Linkage between these two loci was confirmed (with a smaller recombination fraction) by by Landauer (1932, 1933) and Taylor (1934).

Mapping: The linkage group to which this locus belongs became known as linkage group II, which was later shown to be located on chromosome GGA7 (Vaez et al., 2008). A GGA7 location was confirmed by Dorshorst et al. (2010), the most likely region being 16.9–22.4 Mb.

Molecular basis: Having observed substantial suppression of recombination in the vicinity of the mapped Rose-comb locus on chromosome GGA7, Imsland et al. (2012) suspected that the trait could be associated with an inversion. Genomic resequencing subsequently confirmed "a 7.38 Mb inversion with breakpoints located approximately at 16.50 Mb and 23.88 Mb". The Rose-comb phenotype arises because the inversion results in "the relocalization of the MNR2 homeodomain protein gene leading to transient ectopic expression of MNR2 during comb development". Naming this Rose-comb allele R1, Imsland et al. (2012) also report a second Rose-comb allele (R2), which "must have originated by a recombination event between the wild-type allele at position 16.50 Mb and the R1 allele at position 23.79 Mb in the inverted region . . . . The consequence of this recombination event is that R2 does not carry the entire inversion but instead has two duplicated segments, one 91 kb fragment (23,790,414–23,881,384 bp) that represents a remaining fragment of the inverted region together with a small duplicated fragment of 198 bp (16,499,583–16,499,781 bp) that is present on both sides of the 91 kb duplication". The same authors also were able to provide a molecular explanation for the very first example of epistasis (interaction between genes) ever reported (by Bateson and Punnett, 1908), namely the walnut comb, which results from the combined action of Rose-comb and Pea-comb alleles (see OMIA 000782-9031): "Transient ectopic expression of MNR2 and SOX5 (causing the Pea-comb phenotype) occurs in the same population of mesenchymal cells and with at least partially overlapping expression in individual cells in the comb primordium". Finally, Imsland et al. (2012) were also able to provide an explanation for the well-documented pleiotropic effect of Rose-comb, namely that male homozygotes have poor sperm motility (see Crawford and Merritt, 1963, and many more recent references in the list below). The authors propose that this pleiotropy arises from the inversion breakpoint of allele R1 coinciding with a gene (CCDC108) whose encoded peptide includes a major sperm protein domain.

Associated gene:

Symbol Description Species Chr Location OMIA gene details page Other Links
MNR2 homeodomain protein Gallus gallus 7 NC_052538.1 (21939517..21945447) MNR2 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
Rose comb MNR2 inversion a 7.38 Mb inversion 2012 22761584


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.
2012 Imsland, F., Feng, C., Boije, H., Bed'hom, B., Fillon, V., Dorshorst, B., Rubin, C-J., Liu, R., Gao, Y., Gu, X., Wang, Y., Gourichon, D., Zody, M.C., Zecchin, W., Vieaud, A., Tixier-Boichard, M., Hu, X., Hallböök, F., Li, N., Andersson, L. :
The Rose-comb Mutation in Chickens Constitutes a Structural Rearrangement Causing Both Altered Comb Morphology and Defective Sperm Motility PLoS Genetics 8(6):e1002775, 2012. Pubmed reference: 22761584. DOI: 10.1371/journal.pgen.1002775.
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.
2008 Vaez, M., Follett, SA., Bed'hom, B., Gourichon, D., Tixier-Boichard, M., Burke, T. :
A single point-mutation within the melanophilin gene causes the lavender plumage colour dilution phenotype in the chicken. BMC Genet 9:7, 2008. Pubmed reference: 18197963. DOI: 10.1186/1471-2156-9-7.
1996 Mclean, D.J., Froman, D.P. :
Identification of a sperm cell attribute responsible for subfertility of roosters homozygous for the rose comb allele Biology of Reproduction 54:168-172, 1996. Pubmed reference: 8838014.
1994 Kirby, J.D., Engel, H.N., Froman, D.P. :
Analysis of Subfertility Associated with Homozygosity of the Rose Comb Allele in the Male Domestic Fowl Poultry Science 73:871-878, 1994. Pubmed reference: 8072931.
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.
1992 Froman, D.P., Kirby, J.D., Alaghbari, A.M. :
Analysis of the Combined Effect of the Spermatozoal Degeneration Allele (Sd) and Homozygosity of the Rose Comb Allele (R) on the Duration of Fertility of Roosters (Gallus domesticus) Poultry Science 71:1939-1942, 1992. Pubmed reference: 1437982.
1981 Petitjean, M., Servouse, M. :
Comparative study of some characteristics of the semen of RR (rose comb) or rr (single comb) cockerels. Reprod Nutr Dev 21:1085-93, 1981. Pubmed reference: 6218547.
1974 Etches, RJ., Buckland, RB., Hawes, RO. :
The effect of the genes for rose comb and polydactyly on sperm transport in the hen's oviduct. Poult Sci 53:422-4, 1974. Pubmed reference: 4833050.
1972 Brumbaugh, JA., Chatterjee, G., Hollander, WF. :
Adendritic melanocytes: a mutation in linkage group II of the fowl. J Hered 63:19-25, 1972. Pubmed reference: 5019540.
1971 Crawford, R.D. :
Rose comb and fertility in silver Spangled Hamburgs. Poult Sci 50:867-9, 1971. Pubmed reference: 5569770.
1969 Buckland, R.B., Wilcox, F.H., Shaffner, C.S. :
Influence of homozygosity for rose comb on fumarase, aconitase, isocitric dehydrogenase and malic dehydrogenase activity in spermatozoa of the domestic fowl (Gallus domesticus). J Reprod Fertil 18:89-95, 1969. Pubmed reference: 5791687.
1968 Buckland, RB., Hawes, RO. :
Comb type and reproduction in the male fowl segregation of the rose and pea comb genes. Can J Genet Cytol 10:395-400, 1968. Pubmed reference: 5699835.
1965 Crawford, R.D., Smyth, J.R. :
Infertility and action of the genes for rose comb in the domestic fowl Biological Abstracts 46:24-, 1965.
Crawford, R.D., Smyth, J.R. :
The influence of comb genotype on mating behaviour in the domestic fowl Poultry Science 44:115-122, 1965. Pubmed reference: 14336869.
1964 Crawford, R.D., Smyth, J.R. :
Semen quality and the gene for rose comb in the domestic fowl Poultry Science 43:1551-1557, 1964.
Crawford, R.D., Smyth, J.R. :
Infertility and action of the gene for Rose comb in the domestic fowl Can J Genet Cytol 259:298-303, 1964. Pubmed reference: 14208710.
Crawford, R.D., Smyth, R.J. :
Studies of the relationship between fertility and the gene for rose comb in the domestic fowl. I. The relationship between comb genotype and fertility Poultry Science 43:1009-1017, 1964.
1963 Crawford, R.D., Merritt, E.S. :
The relationship between rose comb and reproduction in the domestic fowl Canadian Journal of Genetics and Cytology 5:89-95, 1963. Pubmed reference: 14023733.
Merat, P. :
Abnormal segregations for the alleles 'single comb' and 'Rose comb' in the domestic fowl Genetics Today. Proceedings of the Eleventh International Congress of Genetics, The Hague 1:259 Abstract, 1963.
Merat, P. :
[Abnormal segregation for the alleles 'single comb' and 'rose comb' in the fowl. IV. Combined discussion on the three tupes of cross, RrXrr. rrXRr and RrXRr] Annales de Biologie Animale, Biochimie, Biophysique 3:133-141, 1963.
Merat, P. :
[Abnormal segregation for the alleles 'single comb' and 'rose comb' in the fowl. II. rr male x Rr female] Annales de Biologie Animale, Biochimie, Biophysique 3:59-64, 1963.
1949 Warren, DC. :
Linkage Relations of Autosomal Factors in the Fowl. Genetics 34:333-50, 1949. Pubmed reference: 17247319.
1938 Fisher, R.A. :
Dominance in poultry - Feathered feet, rose comb, internal pigment and pile. Proceedings of the Royal Society, Series B: Biological Sciences 125:25-48, 1938.
Warren, D.C. :
Mapping the genes of the fowl (abstract) Genetics 23:174 only, 1938.
1934 Taylor, L.W. :
Creeper and single-comb linkage in the fowl. Journal of Heredity 25:205-206, 1934.
1933 Landauer, W. :
Creeper and single-comb linkage in fowl. Nature 132:606 only, 1933.
Warren, D.C. :
Nine Independently Inherited Autosomal Factors in the Domestic Fowl. Genetics 18:68-81, 1933. Pubmed reference: 17246678.
1932 Landauer, W. :
Studies on the Creeper Fowl. V. The linkage of the genes for Creeper and Single-comb. Journal of Genetics 26:285-290, 1932.
1928 Serebrovsky, A.S., Petrov, S.G. :
A case of close autosomal linkage in the fowl Journal of Heredity 19:305-306, 1928.
1908 Bateson, W., Punnett, R.C. :
Experimental studies in the physiology of heredity. Poultry Reports of the Evolution Committee of the Royal Society 4:18-35, 1908.
1905 Bateson, W., Punnett, R.C. :
Experimental studies in the physiology of heredity. Poultry. Reports to the Evolution Committee of the Royal Society II:99-119, 1905.
Bateson, W., Punnett, R.C. :
A suggestion as to the nature of the "walnut"comb in fowls Proceedings of the Cambridge Philosophical Society 13:165-168, 1905.
1902 Bateson, W. :
Experimental studies in the physiology of heredity. Part II. Poultry Reports to the Evolutionary Committee of the Royal Society 1:87-124, 1902.
Bateson, W., Saunders, E.R. :
The facts of heredity in the light of Mendel's discovery Reports to the Evolution Committee of the Royal Society 1:125-160, 1902.

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