Andersson, Leif
- Department of Animal Biosciences, Swedish University of Agricultural Sciences
- Texas A&M University
- Uppsala University
Research article2019Peer reviewedOpen access
McCoy, Annette M.; Beeson, Samantha K.; Rubin, Carl-Johan; Andersson, Leif; Caputo, Paul; Lykkjen, Sigrid; Moore, Alison; Piercy, Richard J.; Mickelson, James R.; McCue, Molly E.
Several horse breeds have been specifically selected for the ability to exhibit alternative patterns of locomotion, or gaits. A premature stop codon in the gene DMRT3 is permissive for gaitedness across breeds. However, this mutation is nearly fixed in both American Standardbred trotters and pacers, which perform a diagonal and lateral gait, respectively, during harness racing. This suggests that modifying alleles must influence the preferred gait at racing speeds in these populations. A genome-wide association analysis for the ability to pace was performed in 542 Standardbred horses (n = 176 pacers, n = 366 trotters) with genotype data imputed to similar to 74,000 single nucleotide polymorphisms (SNPs). Nineteen SNPs on nine chromosomes (ECA1, 2, 6, 9, 17, 19, 23, 25, 31) reached genome-wide significance (p < 1.44 x 10(-6)). Variant discovery in regions of interest was carried out via whole-genome sequencing. A set of 303 variants from 22 chromosomes with putative modifying effects on gait was genotyped in 659 Standardbreds (n = 231 pacers, n = 428 trotters) using a high-throughput assay. Random forest classification analysis resulted in an out-of-box error rate of 0.61%. A conditional inference tree algorithm containing seven SNPs predicted status as a pacer or trotter with 99.1% accuracy and subsequently performed with 99.4% accuracy in an independently sampled population of 166 Standardbreds (n = 83 pacers, n = 83 trotters). This highly accurate algorithm could be used by owners/trainers to identify Standardbred horses with the potential to race as pacers or as trotters, according to the genotype identified, prior to initiating training and would enable fine-tuning of breeding programs with designed matings. Additional work is needed to determine both the algorithm's utility in other gaited breeds and whether any of the predictive SNPs play a physiologically functional role in the tendency to pace or tag true functional alleles.
PLoS Genetics
2019, Volume: 15, number: 5, article number: e1008146Publisher: PUBLIC LIBRARY SCIENCE
Genetics and Breeding
DOI: https://doi.org/10.1371/journal.pgen.1008146
https://res.slu.se/id/publ/100679