SRY negative 64,XX intersex phenotype in an American saddlebred horse.
Abstract: A female American saddlebred horse was presented for surgical correction of a possible pseudohermaphrodite condition. The horse had abnormal external genitalia and exhibited stallion-like behaviour. No evidence of uterine or ovarian tissue was identified on laparoscopic examination, but hypoplastic testicular-like tissue was removed, although this was found to contain no spermatogonia upon histopathological examination. A karyotype was performed and showed the normal chromosomal complement for a female horse (64,XX). Polymerase chain reaction to detect the SRY gene was negative in peripheral blood as well as the testicular-like tissue. This case represents the first report of an SRY negative XX-male sex reversal intersex phenotype, which is a potentially inherited condition, in an American saddlebred horse.
Publication Date: 2005-12-28 PubMed ID: 16386440DOI: 10.1016/j.tvjl.2005.11.008Google Scholar: Lookup
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Summary
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This research article documents the first reported case of a rare phenomenon observed in a female American saddlebred horse. The horse displayed male traits but was genetically found to be female.
Understanding the Intersex Condition
- The focus of this research is an American saddlebred horse that outwardly exhibits traits of both sexes. It was presented for surgery due to a suspected condition termed pseudohermaphrodite – a condition where the individual appears to be one sex but has the internal organs or chromosomes of the other.
- When examined, the horse demonstrated abnormal external genitalia and exuded behaviour typical of a stallion (male horse). Internal examination revealed no uterine or ovarian tissue commonly associated with females. Instead, it had underdeveloped tissue similar to a male’s testicles.
Genetic Analysis
- The researchers performed a karyotype – a test designed to identify the number and appearance of chromosomes in a cell. The results showed the horse had 64,XX chromosomes, which is the common chromosomal structure for a female horse.
- Further molecular analysis deployed the polymerase chain reaction (PCR) technique to detect the presence of the SRY gene. The SRY gene is typically found on the Y chromosome and plays a vital role in male development. It was absent in both the horse’s blood and the testicular-like tissue, further affirming the finding that the horse was genetically female.
Significance of the Findings
- This case represents the first report of a sex reversal intersex phenotype in an American saddlebred horse where the horse is genetically female (SRY negative XX) but exhibits male physical traits (XX male sex reversal intersex phenotype).
- This could potentially be an inherited condition, but further research is required to confirm these conclusions. This finding is of significant interest to veterinarians, equine geneticists and anyone concerned with the genetics and physiology of intersex conditions.
Cite This Article
APA
Bannasch D, Rinaldo C, Millon L, Latson K, Spangler T, Hubberty S, Galuppo L, Lowenstine L.
(2005).
SRY negative 64,XX intersex phenotype in an American saddlebred horse.
Vet J, 173(2), 437-439.
https://doi.org/10.1016/j.tvjl.2005.11.008 Publication
Researcher Affiliations
- Department of Population Health and Reproduction, School of Veterinary Medicine, University of California, Davis, CA 95616, USA. dlbannasch@ucdavis.edu
MeSH Terms
- Animals
- Disorders of Sex Development / diagnosis
- Disorders of Sex Development / veterinary
- Female
- Genitalia / abnormalities
- Horse Diseases / diagnosis
- Horse Diseases / genetics
- Horses / genetics
- Horses / physiology
- Karyotyping
- Phenotype
- Sex Differentiation
- Sex-Determining Region Y Protein / genetics
- Sex-Determining Region Y Protein / metabolism
Citations
This article has been cited 6 times.- Bugno-Poniewierska M, Raudsepp T. Horse Clinical Cytogenetics: Recurrent Themes and Novel Findings. Animals (Basel) 2021 Mar 16;11(3).
- Laseca N, Anaya G, Peña Z, Pirosanto Y, Molina A, Demyda Peyrás S. Impaired Reproductive Function in Equines: From Genetics to Genomics. Animals (Basel) 2021 Feb 3;11(2).
- Peretti V, Satué K, Ciotola F, Cristarella S, De Majo M, Biondi V, D'Anza E, Albarella S, Quartuccio M. An Unusual Case of Testicular Disorder in Sex Development of Arabian Mare (64,XX SRY-Negative). Animals (Basel) 2020 Oct 25;10(11).
- Rossi E, Radi O, De Lorenzi L, Vetro A, Groppetti D, Bigliardi E, Luvoni GC, Rota A, Camerino G, Zuffardi O, Parma P. Sox9 duplications are a relevant cause of Sry-negative XX sex reversal dogs. PLoS One 2014;9(7):e101244.
- Kropatsch R, Dekomien G, Akkad DA, Gerding WM, Petrasch-Parwez E, Young ND, Altmüller J, Nürnberg P, Gasser RB, Epplen JT. SOX9 duplication linked to intersex in deer. PLoS One 2013;8(9):e73734.
- Silversides DW, Benoit JM, Collard F, Gilson C. Disorder of sex development (XX male, SRY negative) in a French bulldog. Can Vet J 2011 Jun;52(6):670-2.
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