Original Article

Three autosomal chromosome translocations associated with repeated early embryonic loss (REEL) in the domestic horse (Equus caballus)
T.L. Lear^a, J. Lundquist^a, W.W. Zent^b, W.D. Fishback, Jr.^b, A. Clark<sup>c

a</sup>Maxwell H. Gluck Equine Research Center, Veterinary Science Department, University of Kentucky
^bHagyard Equine Medical Institute, Lexington, KY (USA);
^cEliza Park, Kerrie (Australia)

Address of Corresponding Author

Cytogenet Genome Res 2008;120:117-122 (DOI: 10.1159/000118749)

  Abstract.

Repeated early embryonic loss (REEL) represents a considerable economic loss to the horse industry. Mares that experience REEL may be overlooked as poten- tial 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.

Copyright © 2008 S. Karger AG, Basel

  Author Contacts

Request reprints from Teri L. Lear, Ph.D.
Maxwell H. Gluck Equine Research Center
Veterinary Science Department, University of Kentucky
Lexington, KY 40546 (USA)
telephone: +1 859 257 4757 ext 81108; fax: +1 859 257 8542
e-mail equigene@uky.edu

  Article Information

Part of this work was supported by the Morris Animal Foundation. This work was done in connection with a project of the University of Kentucky Agricultural Experiment Station and published as paper 07-14-115.

Accepted in revised form for publication by M. Schmid,: 5 December 2007.
Published online: April 30, 2008
Number of Print Pages : 6
Number of Figures : 3, Number of Tables : 1, Number of References : 23