Peer-reviewed veterinary case report
Sex reversal syndrome in the horse: four new cases of feminization in individuals carrying a 64,XY SRY negative chromosomal complement.
- Journal:
- Animal reproduction science
- Year:
- 2014
- Authors:
- Anaya, Gabriel et al.
- Affiliation:
- Department of Genetics · Spain
- Species:
- horse
Plain-English summary
In this study, researchers looked at four horses, three of which were Pura Raza Española and one Menorquín, that showed a mismatch between their genetic makeup and their physical appearance. All four horses had a specific chromosomal abnormality (64,XY SRY negative disorder in sexual development) but looked like normal female horses on the outside. This condition is rare and might go unnoticed because the signs are not obvious, and only older horses showed slight issues with their reproductive organs. The findings suggest that using genetic tests could help veterinarians understand unexplained breeding problems in horses better. Overall, the study highlights the importance of genetic testing in diagnosing these kinds of issues in horses.
Abstract
Horses are characterized as having a greater rate of chromosomal abnormalities than other species, which are mainly related to the sex chromosome pair and produce a series of different anomalies known as disorders in sexual development (DSD). In the present study, three Pura Raza Española (PRE) and one Menorquín (MEN) horses were studied and an incompatibility in their genetic and phenotypic sex were detected. Animals were karyotyped by conventional and molecular cytogenetic analyses and characterized using genomic techniques. Although all individuals, were totally unrelated, these animals had the same abnormality (64,XY SRY negative DSD) despite having an anatomically normal external mare phenotype. Therefore, this syndrome could remain undiagnosed in a large percentage of cases because the physiological and morphological symptoms are rare. In the present study, a slight gonadal dysgenesis was observed only in older individuals. Interestingly this chromosomal abnormality has been previously reported less than twenty times, and never in the PRE or MEN horses. With the present research, it is demonstrated that the use of genetic and cytogenetic diagnostic tools in veterinary practice could be an important complementary test to determine the origin of unexplained reproductive failures among horses.
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Search related cases →Original publication: https://pubmed.ncbi.nlm.nih.gov/25308063/