Application of arm-specific painting probes of horse X chromosome for karyotype analysis in an infertile Hutsul mare with 64,XX/65,XX+Xp karyotype: case report.

The study analyzes the chromosomes of an infertile Hutsul mare through a technique called fluorescence in situ hybridization. Results confirmed a chromosomal abnormality, which could be the cause of the horse’s infertility.

Research Methodology

• The research focused on a 5-year-old Hutsul mare that was infertile. This horse was subjected to a cytogenetic analysis, a scientific method that looks at the structure and number of chromosomes.
• The technique used for this analysis was Fluorescence in situ Hybridisation (FISH). It is a molecular cytogenetic method that uses fluorescent probes that bind to specific parts of a DNA sequence on a chromosome. It is significant in detecting and locating specific DNA sequences on chromosomes.
• Two specific equine Xp and Xq chromosome painting probes were used for this process. These probes were generated through a different method called chromosome microdissection. This is a technique where chromosomes are physically isolated and their DNA is further used to generate probes for FISH.
• In this research, a large number of chromosome spreads (525) were analyzed to ensure accuracy and reliability of the study.

Research Findings

• The number of chromosomes a regular horse cell has is 64. However, the analyzed Hutsul mare had two types of karyotypes: normal 64,XX and abnormal 65,XX+Xp.
• The abnormal karyotype 65,XX+Xp was found in 0.6% of the analyzed cells (that is slightly over 3 of 525 cells), while the majority of cells (99.4%) showed normal 64,XX karyotype.
• This finding suggests that the mare has a rare mosaic form of trisomy X, which means some of her cells have an extra copy of X chromosome (three instead of normal two), leading to the abnormal 65,XX+Xp karyotype.

Conclusions and Interpretations

• The researchers’ goal was to apply chromosome microdissection and the FISH technique for cytogenetic diagnostics, which they successfully accomplished.
• It’s inferred that the presence of two different karyotypes, especially the abnormal 65,XX+Xp, might be the cause of the mare’s infertility, according to similar situations in human genetics.
• However, more research needs to be conducted to confirm this causation and explore the direct consequences of this chromosomal abnormality in horses. The study herein paves the path for further investigations in related fields.