Assessment of genomic inbreeding in Polish Konik horses.

This study set out to gauge the inbreeding coefficients of Polish Konik horses via runs of homozygosity (ROH) through genetic testing. The research identified a genetic balance within the population and revealed inbreeding percentages that varied based on length of ROH.

Understanding the Research Process

• The study focused on Polish Konik horses and attempted to measure their inbreeding coefficient—a way to ascertain how closely related parents of an organism are, in this case, the horses. It used runs of homozygosity (ROH) as the method of assessment. ROH refers to continuous lengths within an individual’s DNA that is made up of identical pairs inherited from both parents. Higher ROH values could indicate higher levels of inbreeding.
• Ninety-six horses across six herds all over Poland were chosen for the study. They were genotyped using the EquineSNP60 BeadChip produced by Illumina, a tool that enables researchers to analyze tens of thousands of single nucleotide polymorphisms (SNPs) simultaneously. SNPs are variations at a single position in a DNA sequence among individuals.
• SNC markers that had a minor allele frequency (which denotes the smallest frequency at which the less common allele occurs in a given population) lower than 0.01 were excluded from the study. Additionally, SNPs that were assigned to the X and Y chromosomes were also eliminated. All measures were subjected to statistical analysis using SVS software (Golden Helix).

Key Findings

• The analysis revealed that the Polish Konik horse population was in genetic equilibrium—meaning, the frequencies of alleles (different versions of the same gene) were constant from generation to generation. The estimates of heterozygosity (the measure of genetic variation at individual levels in a population) for both expected (He) and observed (Ho) were found to be equal at 0.3086.
• Seven categories of ROH lengths were set, ranging from >0.5 to >25 Mb (Megabases, a unit of length for DNA segments). The genomic inbreeding coefficient, derived from ROH (FROH), ranged from 15.96% for the shortest ROHs to 2.71% for the longest ROHs.
• At an individual level, the inbreeding coefficients ranged from 5.25% to 22.41% for ROHs more than 1Mb.

Implications of the Study

• The research’s primary utility lies in contributing to the effective management of inbreeding among Polish Konik horses in the future. High levels of inbreeding can lead to reduced genetic variability, making populations less adaptable to changes in the environment, and increasing the risk of genetic disorders.