The Use of Molecular and Cytogenetic Methods as a Valuable Tool in the Detection of Chromosomal Abnormalities in Horses: A Case of Sex Chromosome Chimerism in a Spanish Purebred Colt

Abstract

Chromosomal abnormalities associated to sex chromosomes are reported as a problem more common than believed to be in horses. Most of them remain undiagnosed due to the complexity of the horse karyotype and the lack of interest of breeders and veterinarians in this type of diagnosis. Approximately 10 years ago, the Spanish Purebred Breeders Association implemented a DNA paternity test to evaluate the pedigree of every newborn foal. All candidates who showed abnormal or uncertain results are routinely submitted to cytogenetical analysis to evaluate the presence of chromosomal abnormalities. We studied the case of a foal showing 3 and even 4 different alleles in several loci in the short tandem repeat (STR) -based DNA parentage test. To confirm these results, a filiation test was repeated using follicular hair DNA showing normal results. A complete set of conventional and molecular cytogenetic analysis was performed to determine their chromosomal complements. C-banding and FISH had shown that the foal presents a sex chimerism 64,XX/64,XY with a cellular percentage of approximately 70/30, diagnosed in blood samples. The use of a diagnostic approach combining routine parentage QF-PCR-based STR screening tested with classical or molecular cytogenetic analysis could be a powerful tool that allows early detection of foals that will have a poor or even no reproductive performance due to chromosomal abnormalities, saving time, efforts and breeders' resources.

Morphological and genetic diversity of Pura Raza Español horse with regard to the coat colour

“…DNA was extracted using the QIAamp 96 DNA Blood Kit (Qiagen, Hilden, Germany) and genotyped using the standard STR panel for horses of the International Society for Animal Genetics (Table S1, Demyda-Peyrás et al, 2013). Blood samples were obtained from the jugular vein by the official veterinary services of the ANCCE.…”

Sex chromosomal abnormalities associated with equine infertility: validation of a simple molecular screening tool in the Purebred Spanish Horse

“…More recently, using a similar approach, we determined the presence of such abnormalities in two Andalusian horses using a simple DNA sample (Demyda‐Peyras et al . ; Demyda‐Peyrás et al . ).…”

Sex reversal syndrome in the horse: Four new cases of feminization in individuals carrying a 64,XY SRY negative chromosomal complement

“…Furthermore, a number of animals carrying these genetic diseases have no external phenotypic changes (Demyda-Peyras et al, 2013). Due to this, a greater percentage of animals remains undiagnosed and the real prevalence of this abnormality in impacting important http://dx.doi.org/10.1016/j.anireprosci.2014.09.020 0378-4320/© 2014 Elsevier B.V. All rights reserved.…”