OMIA:000452-9031 : Henny feathering in Gallus gallus (chicken)

Categories: Homeostasis / metabolism phene

Links to possible relevant human trait(s) and/or gene(s) in OMIM: 107910 (gene) , 139300 (trait)

Mendelian trait/disorder: yes

Mode of inheritance: Autosomal

Considered a defect: yes

Key variant known: yes

Year key variant first reported: 1991

Species-specific symbol: Hf

Species-specific description: The typical feathering of hens is part of their secondary sexual characteristics, produced by the action of oestrogen. Much of this oestrogen is produced from androgen in the ovaries by the enzyme aromatase. In certain strains of two breeds of chicken, namely the Sebright Bantam and the Golden Campine, roosters have the same feathering as hens, rather than the typical male form of feathering. This disorder is called henny feathering. It results from a mutation in the aromatase gene, causing the gene to be expressed in the skin of both sexes. In males, this leads to abnormally high levels of oestrogen, which in turn produces henny feathering. Henny feathering is interesting because it illustrates that not all mutations result in loss of activity; some mutations can cause a gene to be switched on in cells in which it is normally inactive.

History: It seems that the henny feathering trait was first observed by Sir John Sebright in 1800 (Tegetmeier, 1867), and became a distinguishing feature of the Sebright Bantam breed. From this breed, the mutation appears to have spread to other breeds, including the Golden Campine.

Inheritance: The aromatase gene is autosomal, but the form of inheritance of henny feathering is not what is normally seen with an autosomal mutation, because the phenotype associated with the mutation (henny feathering in males) can be seen only in males. This is an example of a sex-limited trait. Furthermore, the normal expression of the gene is seen only in females. Thus the two alleles at the one locus give rise to the two possible forms of sex-limited inheritance. The henny-feathering mutation also illustrates how two alleles can present more than one form of inheritance, depending on which trait is being considered. With respect to aromatase activity, gene action is co-dominant, i.e. heterozygotes have an enzyme activity mid-way between that of the two homozygotes. In this case, however, the activity in the skin of the normal homozygote is zero. With respect to feathering, the mutant is dominant, because heterozygotes produce sufficient enzyme in the skin, and hence sufficient oestrogen, to cause henny feathering.

Mapping: Li et al. (2019) showed that the exact location of the insertion is "at position 9,683,879 bp on chromosome 10 of GalGal6, which is in the 5′ untranslated region (5’UTR) of CYP19A1".

Molecular basis: By cloning and sequencing a very likely candidate gene (based on knowledge that the disorder is due to aberrant expression of the enzyme aromatase) Matsumine et al. (1991) showed that the disorder is due to the terminal repeat sequence of a retrovirus that has been inserted into the 5' promoter region of the aromatase gene. This terminal repeat has a promoter of its own, which causes the aromatase gene to be switched on in atypical places, such as the skin of both sexes, giving rise to the henny-feathering trait in males. The actual peptide produced by the mutant allele is exactly the same as that produced by the normal allele, as we would expect for such a mutation. This disorder is the first insertion mutation documented in any domesticated species of animal. Twenty-eight years after the above pioneering discovery, Li et al. (2019) utilised the full power of advances in genomic technology to fill in the gaps in knowledge understandably inherent in the original discovery of the Hf likely causal variant. They showed that the insertion is 7524bp and "contains an intact endogenous retrovirus [ERV] that was not found in chickens representing 31 different breeds not showing henny feathering or in samples of the ancestral red junglefowl. The sequence shows over 99% sequence identity to the avian leukosis virus ev-1 and ev-21 strains, suggesting a recent integration. The ERV 3’LTR, containing a powerful transcriptional enhancer and core promoter with TATA box together with binding sites for EFIII and Ig/EBP inside the CYP19A1 5′ untranslated region, was detected partially in an aromatase transcript, which present a plausible explanation for ectopic expression of aromatase in non-ovarian tissues underlying the henny feathering phenotype".

Clinical features: Apart from the hen-like feathers, males with this trait have a substantially reduced reproductive ability, probably because the increased levels of plasma oestrogen inhibit spermatogenesis (George et al., 1990).

Associated gene:

Symbol Description Species Chr Location OMIA gene details page Other Links
CYP19A1 cytochrome P450, family 19, subfamily A, polypeptide 1 Gallus gallus 10 NC_052541.1 (9257340..9235646) CYP19A1 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.

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
720 Campine (Chicken) Sebright Bantams, United Kingdom of Great Britain and Northern Ireland (Chicken) Henny feathering CYP19A1 insertion, gross (>20) Naturally occurring variant GRCg6a 10 g.9683879_9683880insN[7524] The insertion is 7524bp and "contains an intact endogenous retrovirus that was not found in chickens representing 31 different breeds not showing henny feathering or in samples of the ancestral red junglefowl. The sequence shows over 99% sequence identity to the avian leukosis virus ev-1 and ev-21 strains, suggesting a recent integration. The ERV 3’LTR, containing a powerful transcriptional enhancer and core promoter with TATA box together with binding sites for EFIII and Ig/EBP inside the CYP19A1 5′ untranslated region" (Li et al., 2019) 1991 1939054 Genomic location and size of the insertion provided by Li et al. (2019)

Cite this entry

Nicholas, F. W., Tammen, I., & Sydney Informatics Hub. (2019). OMIA:000452-9031: 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.

2020 Andersson, L., Bed’hom, B., Chuong, CM., Inaba, M.Inaba, M., Okimoto, R.Okimoto, R., Tixier-Boichard, M. :
The genetic basis for pigmentation phenotypes in poultry In S. E. Aggrey, H. Zhou, M. Tixier-Boichard, & D. D. Rhoads (Eds.), Advances in Poultry Genetics and Genomics. Cambridge, UK: Burleigh Dodds Science Publishing. , 2020.
2019 Li, J., Davis, B.W., Jern, P., Dorshorst, B.J., Siegel, P.B., Andersson, L. :
Characterization of the endogenous retrovirus insertion in CYP19A1 associated with henny feathering in chicken. Mob DNA 10:38, 2019. Pubmed reference: 31467598. DOI: 10.1186/s13100-019-0181-4.
2002 Carefoot, W.C. :
Hen-feathering mutation HF*H may act as a eumelanising factor and modify the expression of autosomal barring British Poultry Science 43:391-394, 2002. Pubmed reference: 12195798. DOI: 10.1080/00071660120103666.
1994 Bitgood, J.J. :
A question on the locations of the tardy feathering and henny feathering loci in the chicken. Poult Sci 73:1485-8, 1994. Pubmed reference: 7816722. DOI: 10.3382/ps.0731485.
1991 Matsumine, H., Herbst, M.A., Ou, S.H.I., Wilson, J.D., Mcphaul, M.J. :
Aromatase messenger RNA in the extragonadal tissues of chickens with the Henny-Feathering trait is derived from a distinctive promoter structure that contains a segment of a retroviral long terminal repeat - Functional organization of the Sebright, Leghorn, and Campine aromatase genes. J Biol Chem 266:19900-7, 1991. Pubmed reference: 1939054.
Tereba, A., McPhaul, M.J., Wilson, J.D. :
The Gene for Aromatase (P450arom) in the Chicken Is Located on the Long Arm of Chromosome-1 Journal of Heredity 82:80-81, 1991. Pubmed reference: 1997594.
1990 George, F.W., Matsumine, H., Mcphaul, M.J., Somes, R.G., Wilson, J.D. :
Inheritance of the Henny Feathering Trait in the Golden Campine Chicken - Evidence for Allelism with the Gene That Causes Henny Feathering in the Sebright Bantam Journal of Heredity 81:107-110, 1990. Pubmed reference: 2338489.
Matsumine, H., Wilson, J.D., Mcphaul, M.J. :
Sebright and Campine Chickens Express Aromatase P-450 Messenger RNA Inappropriately in Extraglandular Tissues and in Skin Fibroblasts Molecular Endocrinology 4:905-911, 1990. Pubmed reference: 1700281.
1988 McPhaul, M.J., Noble, J.F., Matsumine, H., Wilson, J.D. :
Cloning and expression of the chicken ovary aromatase P-450: expression of mRNA in tissues of the Sebright and Leghorn chickens Transactions of the Association of American Physicians 101:219-225, 1988. Pubmed reference: 3269680.
1987 Wilson, J.D., George, F.W., Leshin, M. :
Genetic control of extraglandular aromatase activity in the chicken Steroids 50:235-244, 1987. Pubmed reference: 3504061.
Wilson, J.D., Leshin, M., George, F.W. :
The Seabright bantam chicken and the genetic control of extraglandular aromatose Endocrine Reviews 8:363-376, 1987. Pubmed reference: 3319528.
1986 Hadden, D.R., Mayes, F.J., Bayne, B.E.F., Finlay, L., Leslie, H., Sheridan, B. :
Elevation of serum oestradiol in hen-feathered male Sebright bantams Journal of Endocrinology 108 (Suppl.):abstract 84, 1986.
1985 Leshin, M., Leshin, M. :
5-Azacytidine and sodium butyrate induce expression of aromatase in fibroblasts from chickens carrying the henny feathering trait but not from wild-type chickens. Proc Natl Acad Sci U S A 82:3005-9, 1985. Pubmed reference: 2581260. DOI: 10.1073/pnas.82.9.3005.
1984 Somes, R.G. Jr, George, F.W., Baron, J., Noble, J.F., Wilson, J.D. :
Inheritance of the henny-feathering trait of the Sebright bantam chicken Journal of Heredity 75:99-102, 1984. Pubmed reference: 6715868.
1983 Leshin, M., Noble, J.F., George, F.W., Wilson, J.D. :
Characterization of the increased estrogen synthesis in skin fibroblasts from the Sebright bantam Journal of Steroid Biochemistry 18:33-39, 1983. Pubmed reference: 6683342.
1982 George, F.W., Wilson, J.D. :
Developmental pattern of increased aromatase activity in the Sebright bantam chicken Endocrinology 110:1203-1207, 1982. Pubmed reference: 7060521.
1981 George, F.W., Noble, J.F., Wilson, J.D. :
Female feathering in Sebright cocks is due to conversion of testerone to estradiol in skin Science 213:557-559, 1981.
Leshin, M., Baron, J., George, F.W., Wilson, J.D. :
Increased estrogen formation and aromatase activity in fibroblasts cultured from the skin of chickens with the henny-feathering trait Journal of Biological Chemistry 256:4341-4344, 1981. Pubmed reference: 7217085.
Leshin, M., George, F.W., Wilson, J.D. :
Increased estrogen synthesis in the Sebright bantam is due to a mutation that causes increased aromatase activity Transactions of the Association of American Physicians 94:97-105, 1981. Pubmed reference: 7344234.
1980 George, F.W., Wilson, J.D. :
Pathogenesis of the henny-feathering trait in the Sebright bantam chicken Journal of Clinical Investigation 66:57-65, 1980. Pubmed reference: 7400309. DOI: 10.1172/JCI109835.
1959 Gleichauf, R. :
[Henny feathering in cocks and cock feathering in hens] Celler Jahrbuch. Kleintierzucht in Forschung und Lehre 7:80-82, 1959.
1931 Jull, M.A., Quinn, J.P. :
Inheritance in poultry: data on the genetics of vulture hock, hen feathering and “crooked neck” in the domestic fowl Journal of Heredity 22:147-154, 1931.
1930 Danforth, C.H. :
The nature of racial and sexual dimorphism in the plumage of Campines and Leghorns Biology General 6:99-109, 1930.
1928 Eliot, T.S. :
The influence of the gonads on the plumage of Sebright bantams Physiological Zoology 1:286-323, 1928.
1921 Punnett, R.C., Bailey, P.G. :
Genetic studies in poultry. III. Hen-feathered cocks Journal of Genetics 11:37-62, 1921.
1920 Morgan, T.H. :
The effects of castration of hen-feathering Campines Biological Bulletin 39:231-247, 1920.
1918 Boring, A.M., Morgan, T.H. :
Lutear cells and hen-feathering J Gen Physiol 1:127-31, 1918. Pubmed reference: 19871722. DOI: 10.1085/jgp.1.1.127.
1914 Hewes, T., Clarke, H.P. :
The book of the Campines Inland Poultry Journal :18-22, 1914.
Jones, E.L. :
Making of the English type gold Campine male Farm Poultry :113, 1914.
1867 Tegetmeier, W.B. :
The Poultry Book: comprising the breeding and management of profitable and ornamental Poultry With coloured illustrations by Harrison Weir, etc. London. , 1867.

Edit History

  • Created by Frank Nicholas on 12 Sep 2005
  • Changed by Frank Nicholas on 01 Sep 2011
  • Changed by Frank Nicholas on 09 Dec 2011
  • Changed by Frank Nicholas on 16 Mar 2012
  • Changed by Frank Nicholas on 19 Sep 2012
  • Changed by Frank Nicholas on 19 Jun 2013
  • Changed by Frank Nicholas on 03 Sep 2019