Analysis of a candidate gene for behavioural trait variability in horses: catechol-O-methyltransferase (COMT).

The research focuses on the analysis of the catechol-O-methyltransferase (COMT) gene in horses. The study was specifically interested in the role this gene might have in behavioral trait variability due to its function in the metabolism of neurotransmitters, especially dopamine.

Overview of the COMT Gene

• The COMT gene is structured with six exons, where the initial two are non-coding, along with two alternative promoters. When expressed, it results in mRNA transcripts that are divergent at the 5′ end and leads in synthesizing at least two different enzymes.
• The one enzyme with extensive extension at the C-terminal end is a membrane-bound protein (MB-COMT) mainly found in the brain. The other one is a soluble form (S-COMT) that is present in many tissues.
• These two isoforms are crucial in the catabolism process of catecholamines, notably neurotransmitter like dopamine, along with their metabolites and L-DOPA substrates.

COMT and Behavioral Traits

• Due to its functionality and experimental results identified in humans and rodents, the COMT gene is inspected as a potential gene for variability in several traits. These include cognitive function, anxiety levels, aggression, pain sensitivity, and behavior related to sexual activity.
• Understanding the variance in genes responsible for behavioral traits is especially essential for horses as it affects their sport performance, suitability for use in equestrian tourism, and in equine-assisted therapies.
• However, previous researches on the COMT gene in horses remained limited.

Objective of the Research

• This research was conducted to examine the COMT gene regions in various horse samples (Equus caballus) to look for any polymorphisms.
• The COMT gene coding regions were sequenced in 10 horses from the Thoroughbred breed, and 4 single nucleotide polymorphisms (SNPs) were identified.