Peer-reviewed veterinary case report
Cytogenetic and molecular characterization of Y isochromosome in a 63XO/64Xi(Yq) mosaic karyotype of an intersex horse.
- Journal:
- Sexual development : genetics, molecular biology, evolution, endocrinology, embryology, and pathology of sex determination and differentiation
- Year:
- 2012
- Authors:
- Das, P J et al.
- Affiliation:
- Department of Veterinary Integrative Biosciences · United States
- Species:
- horse
Plain-English summary
This study looked at a unique case of an intersex horse, which means the horse has both male and female characteristics. The horse had a mix of two types of cells in its blood: most were typical male cells, while a smaller portion had an unusual Y chromosome structure. The researchers found that this abnormal Y chromosome still had important genes that are usually found in male horses, including one that plays a key role in male development. They believe that the presence of this intact gene in some of the horse's cells is what caused its intersex traits. Overall, the findings suggest that the horse's condition is linked to this unusual chromosome structure, but more research is needed to understand its implications for other animals.
Abstract
Sex chromosome aberrations commonly lead to abnormal sexual development. Here we cytogenetically and molecularly characterized Y isochromosome in an intersex horse. Blood lymphocyte analysis showed a mosaic karyotype with 96% 63,XO and 4% 64,Xi(Y) cells. Molecular analysis of the isochromosome was carried out by fluorescence in situ hybridization and polymerase chain reaction with male-specific and pseudoautosomal markers from the horse Y chromosome. We found that the isochromosome was monocentric, composed of 2 long arms, carrying 2 sets of genes of the pseudoautosomal region (PAR) and the male-specific region of the Y (MSY), including the SRY - thus being genetically equivalent to Y disomy. Sequence analysis of a 1,955-bp region including the SRY exon, the promoter and the UTRs, revealed no mutations in the aberrant Y. The presence of an intact SRY in a small proportion of cells is the proposed cause for the intersex phenotype. Given that the i(Yq) was present in a mosaic form, both post-zygotic and meiotic mechanisms of its origin were proposed. We speculated that nonmosaic 64,Xi(Yq) karyotypes might be rare or absent because of the likely instability of the i(Yq) during cell division. Genetic and phenotypic implications of Y isochromosome formation in other mammals are discussed in the light of the diversity of Y chromosome organization between species.
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Search related cases →Original publication: https://pubmed.ncbi.nlm.nih.gov/22005008/