New findings on genes that control Icelandic horses' ability to pass

Researchers at the Swedish University of Agricultural Sciences, together with Icelandic colleagues, have now studied the genetic factors that influence the ability to walk at a walk and the quality of the gait.

In 372 Icelandic horses, 362 of which had gait scores from breeding assessment, 670,000 points in the genome were examined where it is already known that the genetic code often differs between individuals, so-called “SNP” markers.

The analysis revealed that several markers on chromosomes 4, 9 and 20 could be linked to the breeding assessment score for passports. Interestingly, the markers on chromosomes 4 and 9 were located within the RELN and STAU2 genes, which have previously been shown to influence locomotor behavior in mice. The most abundant variant of RELN and STAU2 had a large favorable effect on pass score. The second most abundant variant of RELN was favorably associated with scores for tölt, trot, and canter. Similarly, the second most common variant of STAU2 had favorable effects on trot and canter scores. In addition, associations were found between RELN, STAU2 and the previously known passport gene DMRT3. Together, the newly found gene variants on chromosomes 4, 9 and 20 together with the effects of the DMRT3 variant were estimated to explain over 27% of the variation in passport scores.

These findings provide valuable information on the genetic background of horses' ability in the gaits, beyond the contribution of the DMRT3 gene, and the results indicate that genetic relationships contribute to the complexity of this trait. Further studies are needed to fully understand the genetic background of gaits.

Link to the publication

https://doi.org/10.1186/s12711-023-00863-6

Reference

Sigurðardóttir, H., Boije, H., Albertsdóttir, E. et al. The genetics of gaits in Icelandic horses goes beyond DMRT3, with RELN and STAU2 identified as two new candidate genes. Genet Sel Evol 55, 89 (2023).