Developing equine mtDNA profiling for forensic application.

Area of Science:

• Forensic Science
• Genetics
• Molecular Biology

Background:

• Horse mitochondrial DNA (mtDNA) profiling is valuable for forensic applications, especially with degraded, hair shaft, or dilute samples.
• Sequencing degraded DNA is challenging, often limiting analysis to fragments under 200 nucleotides.

Purpose of the Study:

• To identify the most discriminatory segments within the hypervariable horse mtDNA control region for forensic identification.
• To assess the utility of these segments for profiling challenging forensic samples.

Main Methods:

• Analysis of the hypervariable horse mtDNA control region in a random sample of 39 horses.
• Sequencing of a 921-nucleotide stretch of the mtDNA control region.
• Application of a "sliding window" analysis using 200-nucleotide segments.

Main Results:

• Identification of 32 distinct sequences among 39 horses within the analyzed region.
• Assignment of sequences to published mtDNA types A-G and a new type H.
• A random match probability of 3.61% and an average pairwise sequence difference of 15 nucleotides.
• Discovery that a central repetitive motif divides the control region into highly and less diverse segments.

Conclusions:

• Specific regions within the horse mtDNA control region offer high discriminatory power for forensic profiling.
• The findings are crucial for developing efficient mtDNA profiling strategies for degraded and limited forensic samples.
• Understanding the variability of the mtDNA control region aids in accurate individual identification in forensic casework.