# Connections Between Gene Polymorphism and Fetlock and Hock Measurements in Polish Sport Horses

## TL;DR

This study explores how gene variations in Polish sport horses are linked to bone structure measurements in fetlock and hock joints.

## Contribution

The study identifies specific gene polymorphisms associated with bone structure variations in sport horses, offering insights into genetic influences on musculoskeletal development.

## Key findings

- Heterozygotes of COL9A2, AOAH1, BMPER, HYAL3, and ELMO1 showed larger fetlock bone structures.
- Heterozygotes of COL9A2, HYAL3, ANLN, and HYAL1 had superior hock bone measurements compared to homozygotes.
- Certain homozygous variants (e.g., TT for HYAL3) resulted in lower bone structure values in fetlock and hock joints.

## Abstract

Finding the causative mutations for musculoskeletal system development and health status is of a higher priority for all sport horse breeders’ associations. Of the regulating proteins involved in animal ossification, 15 gene polymorphisms were chosen to be identified as connected with the nine fetlock and 14 hock bone structures measurements of 198 horses. All measurements were taken using X-rays of the limbs, which were available at the beginning and end of the horse training. The analysis of variance (GLM, SAS program) was performed taking into account identified training and horse-connected characteristics, and gene polymorphism. The larger size of the bone structure was achieved in the fetlock for the heterozygotes of COL9A2, AOAH1, BMPER, HYAL3, and ELMO1. The heterozygotes were superior to homozygotes in the hock for the following genes: COL9A2, HYAL3, ANLN, and HYAL1. The lower homozygote values were obtained for GG in CPVL in fetlock measurements, TT for HYAL3 in fetlock, TT for ANLN in fetlock, CC for FRZB in the hock, TT for MATN in the hock, and TT for COL5A2 in the hock than their opposite homozygote and heterozygote variants. COL9A2 and HYAL3 are expressed in the same way for most of the bone structures in both joints.