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XY sex-reversal syndrome in the domestic horse.
Abstract: The XY sex-reversal syndrome occurs when a phenotypic mare is born that has the karyotype of a stallion. The syndrome is manifested by both genotypic and phenotypic heterogeneity. The sex-reversed genetic condition occurs frequently within certain pedigrees where XY females have been found and can be readily detected by chromosome karyotyping. The phenotypic spectrum ranges from the feminine mare with a reproductive tract that is within normal limits to the greatly masculinized mare. Pedigree analysis suggests that there are two modes of inheritance: (1) an X-linked recessive or autosomal sex-limited dominant transmitted through the female and (2) an autosomal sex-limited dominant or a Y chromosomal mutation with variable expression transmitted through the male. The proportion of female to male progeny of the 69 top-producing Arabian stallions in the world is 53 to 47, indicating that the occurrence of genetic defects affecting the sex ratio such as the XY sex-reversal syndrome is relatively infrequent. In nine cases where the sex ratios of stallions deviated significantly from the expected sex ratio, the incidence of female infertility also increased. Cytogenetic screening of young animals would provide for early detection and avoid the expense and disappointment of continuous breeding attempts. Just as importantly, it would aid in the reduction and the possible elimination of this genetic condition from breeding herds.
Publication Date: 1986-01-01 PubMed ID: 3720361DOI: 10.1159/000132243Google Scholar: Lookup The Equine Research Bank provides access to a large database of publicly available scientific literature. Inclusion in the Research Bank does not imply endorsement of study methods or findings by Mad Barn.
- Journal Article
- Research Support
- Non-U.S. Gov't
- Research Support
- U.S. Gov't
- P.H.S.
Summary
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The research investigates a condition known as XY sex-reversal syndrome in horses, where horses that physically appear to be females possess the stallion’s genetic make-up. Evidence suggests that there are two possible inheritance pathways, and the condition seems to be relatively infrequent among horses. The research also points towards a link between unusual sex ratios and increased rates of female infertility. Early screening could potentially prevent breeding difficulties and facilitate the reduction of this condition.
XY Sex-reversal Syndrome Explained
- The XY sex-reversal syndrome can be characterized as a condition where a horse that appears female physically (phenotypic mare) bears the genetic counterparts of a male horse (stallion’s karyotype).
- This condition isn’t universally the same (heterogeneity) and could vary in its manifestation. Sometimes, it may be marked by unquestionably female horses with normal reproductive tracts. At other times, it may present mares that exhibit marked male features.
- Based on the study of lineages (pedigree analysis), there are presumably two ways the genes causing the condition are passed on, either through an X-linked recessive, autosomal sex-limited dominant trait from the mother or an autosomal sex-limited dominant or Y chromosomal mutation with variable expression from the father.
Incidence and Prevalence
- Among the 69 most productive Arabian stallions globally, the female to male progeny ratio is 53 to 47. This suggests that conditions such as XY sex-reversal syndrome that impact the sex ratio should be comparatively rare.
- In nine instances where the stallion’s offspring skewed away from the regular sex ratio, there was a corresponding uptick in female infertility. This might suggest, although further research would be needed to confirm, a potential association between abnormal sex ratios and fertility issues.
Fulfilling the Need for Early Detection
- This study also highlights the usefulness of cytogenetic screening for young horses. By spotting these genetic anomalies early on, breeders can potentially dodge their expenditure upon and disappointment from failed breeding attempts.
- In addition, proactive identification and management of this genetic condition might enable the reduction or even possible elimination of XY sex-reversal syndrome from breeding herds, enhancing overall breeding success and genetic health.
Cite This Article
APA
Kent MG, Shoffner RN, Buoen L, Weber AF.
(1986).
XY sex-reversal syndrome in the domestic horse.
Cytogenet Cell Genet, 42(1-2), 8-18.
https://doi.org/10.1159/000132243 Publication
Researcher Affiliations
MeSH Terms
- Animals
- Chromosome Banding
- Disorders of Sex Development
- Female
- Horse Diseases / genetics
- Horses
- Infertility, Female / genetics
- Infertility, Female / veterinary
- Karyotyping
- Male
- Pedigree
- Phenotype
- Sex Chromosome Aberrations / genetics
- Sex Chromosome Aberrations / veterinary
- Sex Ratio
- X Chromosome
- Y Chromosome
Grant Funding
- AI-23479 / NIAID NIH HHS
Citations
This article has been cited 3 times.- Bugno-Poniewierska M, Raudsepp T. Horse Clinical Cytogenetics: Recurrent Themes and Novel Findings. Animals (Basel) 2021 Mar 16;11(3).
- Kent MG, Shoffner RN, Hunter A, Elliston KO, Schroder W, Tolley E, Wachtel SS. XY sex reversal syndrome in the mare: clinical and behavioral studies, H-Y phenotype. Hum Genet 1988 Aug;79(4):321-8.
- Kent MG, Schneller HE, Hegsted RL, Johnston SD, Wachtel SS. Concentration of serum testosterone in XY sex reversed horses. J Endocrinol Invest 1988 Sep;11(8):609-13.
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