OMIA 000668-9031 : Muffs and beard in Gallus gallus

Possibly relevant human trait(s) and/or gene(s) (MIM number): 142963 (gene)

Mendelian trait/disorder: yes

Mode of inheritance: Autosomal Incompletely Dominant

Considered a defect: yes

Key variant known: yes

Year key variant first reported: 2016

Species-specific symbol: Mb

Species-specific description: "Muffs, also known as whiskers, consist of tufts of feathers projecting horizontally from both sides of the face, and the beard consists of feathers projecting vertically from under the beak in a downward direction; they always appear together." (Somes, 1990)

Inheritance: Davenport (1906) and Serebrovsky and Petrov (1930) reported single-locus autosomal incompletely dominant inheritance. The symbol Mb, proposed by Hutt (1949), replaced Ba which had been proposed by Hertwig (1933). (Somes 1990).

Mapping: Sun et al. (2015) mapped this trait to chromosome GGA27. Yang et al. (2020) “performed a GWAS and QTL linkage analysis on the trait of beard in Beijing fatty chicken. One major QTL (1.2-1.9 Mb) was identified that could explain 34% of the phenotypic variation. The copy number variation that was copied from the region (GGA27:3 578 409-3 592 890 bp) containing homebox B7 (HOXB7) and homebox B8 (HOXB8) was validated to be only exhibited in the genome of bearded chickens.”

Molecular basis: Guo et a. (2016) used "genome-wide association (GWA) analysis, linkage analysis, Identity-by-Descent (IBD) mapping, array-CGH, genome re-sequencing and expression analysis to show that the Mb allele causing the Mb phenotype is a derived allele where a complex structural variation (SV) on GGA27 leads to an altered expression of the gene HOXB8. . . . The Mb allele differs from the wild-type mb allele by three duplications, one in tandem and two that are translocated to that of the tandem repeat around 1.70 Mb on GGA27".

Associated gene:

Symbol Description Species Chr Location OMIA gene details page Other Links
HOXB8 homeobox B8 Gallus gallus 27 NC_052558.1 (3402859..3404508) HOXB8 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.

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.

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 Inferred EVA rsID Year Published PubMed ID(s) Acknowledgements
Huiyang Bearded Muffs and beard HOXB8 complex rearrangement Naturally occurring variant 27 "The Mb allele differs from the wild-type mb allele by three duplications, one in tandem and two that are translocated to that of the tandem repeat around 1.70 Mb on GGA27 2016 27253709


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 Yang, K.X., Zhou, H., Ding, J.M., He, C., Niu, Q., Gu, C.J., Zhou, Z.X., Meng, H., Huang, Q.Z. :
Copy number variation in HOXB7 and HOXB8 involves in the formation of beard trait in chickens. Anim Genet 51:958-963, 2020. Pubmed reference: 33058257. DOI: 10.1111/age.13011.
2016 Guo, Y., Gu, X., Sheng, Z., Wang, Y., Luo, C., Liu, R., Qu, H., Shu, D., Wen, J., Crooijmans, R.P., Carlborg, Ö., Zhao, Y., Hu, X., Li, N. :
A Complex Structural Variation on Chromosome 27 Leads to the Ectopic Expression of HOXB8 and the Muffs and Beard Phenotype in Chickens. PLoS Genet 12:e1006071, 2016. Pubmed reference: 27253709. DOI: 10.1371/journal.pgen.1006071.
2015 Sun, Y., Liu, R., Zhao, G., Zheng, M., Sun, Y., Yu, X., Li, P., Wen, J. :
Genome-Wide Linkage Analysis Identifies Loci for Physical Appearance Traits in Chickens. G3 (Bethesda) 5:2037-41, 2015. Pubmed reference: 26248982. DOI: 10.1534/g3.115.020883.
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.
1990 Somes, R.G. Jr :
Mutations and major variants of plumage and skin in chickens. In "Poultry Breeding and Genetics" (ed. R.D. Crawford), Elsevier, Amsterdam; Chapter 6 :169-208, 1990.
1949 Hutt, F.B. :
Genetics of the fowl. McGraw-Hill, New York. :, 1949.
Warren, DC. :
Linkage Relations of Autosomal Factors in the Fowl. Genetics 34:333-50, 1949. Pubmed reference: 17247319.
1933 Hertwig, P. :
Geschlechtsgebundene und autosomale Koppelungen bei Hiihnern Verh. Deutsch. Zool. Ges . :112-118, 1933.
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.
1906 Davenport, C.B. :
"Inheritance in poultry". Washington, D.C.: Carnegie Institution of Washington. Publication 52. :1-136, 1906. DOI: 10.5962/bhl.title.29926.

Edit History

  • Created by Frank Nicholas on 06 Sep 2005
  • Changed by Frank Nicholas on 26 Nov 2012
  • Changed by Frank Nicholas on 03 Jun 2016
  • Changed by Imke Tammen2 on 27 Oct 2021