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

This research developed a cost-effective, reliable method for detecting major sex chromosome abnormalities in horses, which are known to cause reproductive issues. The technique, which relies on single-tandem-repeat (STR) markers, proved highly accurate in a test group of Purebred Spanish Horses.

Method Development

• The researchers designed an STR-based molecular mechanism. STRs or Single Tandem Repeats are short sequences of DNA that repeat themselves, and variations in the number of these repeats can serve as markers for genetic abnormalities.
• They tested the frequency of five ECAX-linked markers (LEX026, LEX003, TKY38, TKY270, and UCDEQ502) and two ECAY-linked markers (EcaYH12 and SRY) in a sample group of 261 Purebred Spanish Horses.
• All the microsatellites analyzed exhibited high polymorphism, i.e., they had a significant number of differing DNA sequences, providing a large amount of information for diagnosing chromosomal issues.

Method Testing and Results

• The newly developed methodology proved to be very effective at diagnosing major sex chromosomal abnormalities in horses, such as chimerism, Turner’s syndrome, and sex reversal syndromes. It showed a sensitivity of 100% and specificity of 99.82%.
• The method was further validated with 100% efficiency in ten horses previously diagnosed as having chromosomal aberrations.

Conclusion and Application

• The novel STR screening tool was concluded to be an efficient, reliable molecular-cytogenetic tool for the early detection of sex chromosomal abnormalities in horses.
• Beyond its diagnostic advantage, the tool can be included in breeding programs, saving breeders and veterinarians significant amounts of money, effort, and time. The early detection and diagnosis of such abnormalities can ensure that only healthy horses are bred, improving the overall quality of the breed.