Peer-reviewed veterinary case report
Three autosomal chromosome translocations associated with repeated early embryonic loss (REEL) in the domestic horse (Equus caballus).
- Journal:
- Cytogenetic and genome research
- Year:
- 2008
- Authors:
- Lear, T L et al.
- Affiliation:
- Veterinary Science Department · United States
- Species:
- horse
Plain-English summary
Repeated early embryonic loss (REEL) is a significant issue for horse breeders, as it can lead to financial losses. In this study, researchers looked at Thoroughbred mares that were having trouble carrying pregnancies to term and found three different chromosome changes that could be causing the problem. They used advanced techniques to confirm these changes and discovered that two of them were reciprocal, meaning the genetic material was swapped between chromosomes, while one was not. The findings suggest that these chromosome abnormalities might be more common in mares with fertility issues than previously thought, highlighting the importance of genetic testing for mares that struggle with early pregnancy loss. Overall, understanding these chromosome changes could help improve breeding outcomes.
Abstract
Repeated early embryonic loss (REEL) represents a considerable economic loss to the horse industry. Mares that experience REEL may be overlooked as potential carriers of a chromosome abnormality. Here we report three different autosomal translocations in Thoroughbred mares presented for chromosome analysis because of REEL. The karyotypes were 64,XX,t(1;21), 64,XX,t(16;22), and 64,XX,t(4;13), respectively. In order to confirm the chromosomes involved in the translocations, to map the breakpoints, and to determine if the translocations were reciprocal, genes surrounding the breakpoints were identified using existing maps and from the newly assembled horse genome sequence. Bacterial artificial chromosomes containing the genes of interest were identified and mapped to the translocation chromosomes by fluorescence in situ hybridization (FISH). FISH confirmed that the t(16;22) and t(4;13) translocations were reciprocal, while the t(1;21) was not. The breakpoints on horse chromosomes 1 and 16 appear to be the same or near breakpoints previously identified in translocations. These breakpoints are at the fusion boundary of human chromosomes 10 and 15 on horse chromosome 1 and at human chromosome 3p and 3q on horse chromosome 16. These sites may represent ancient breakpoints reused during equid evolution. Overall, chromosome abnormalities may have a greater influence on mare fertility than previously known. Thus, it is important to karyotype subfertile mares exhibiting REEL.
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Search related cases →Original publication: https://pubmed.ncbi.nlm.nih.gov/18467834/