Lack of significant associations with early career performance suggest no link between the DMRT3 "Gait Keeper" mutation and precocity in Coldblooded trotters.
Authors: Jäderkvist Fegraeus Kim, Lawrence Chameli, Petäjistö Katrine, Johansson Maria K, Wiklund Maja, Olsson Christina, Andersson Leif, Andersson Lisa S, Røed Knut H, Ihler Carl-Fredrik, Strand Eric, Lindgren Gabriella, Velie Brandon D
Journal: PloS one
Summary
# Editorial Summary: DMRT3 mutation shows no clear performance advantage in Coldblooded trotters The DMRT3 "Gait Keeper" gene mutation has demonstrated strong associations with harness racing success in other breeds, particularly Standardbreds and Finnhorses, leading researchers to hypothesise that the favourable AA genotype might similarly predict early career precocity in Swedish-Norwegian Coldblooded trotters (CBTs). To test this assumption, Fegraeus Kim and colleagues genotyped 769 CBTs (485 active racers, 284 unraced) and analysed 13 performance traits across three age intervals using linear statistical modelling, examining whether DMRT3 variants correlated with racing outcomes from three years of age through to ten years. Contrary to expectations, the study found no significant association between the AA genotype and early career performance; whilst AA horses did record faster race times and CC horses showed higher disqualification rates at three years old, these differences didn't translate into meaningful precocity advantages, and notably, fewer than 50% of AA-genotype horses even entered races at all. The findings suggest that DMRT3's performance benefits—so pronounced in other trotting breeds—do not reliably predict success in CBTs, indicating that breed-specific genetic architecture or management factors may substantially influence how this mutation affects racing outcomes. For breeders and trainers selecting CBTs, reliance on DMRT3 genotyping alone as a marker of racing potential appears unjustified, and individual assessment of conformation, temperament and training response remains essential.
Read the full abstract on PubMed
Practical Takeaways
- •The DMRT3 'gait keeper' mutation does not predict early racing success in Coldblooded trotters, so selection decisions for young CBTs cannot rely on this genetic marker alone
- •AA genotype horses appear under-represented in racing populations for reasons other than performance advantage, suggesting breed-specific factors influence both genetics and racing participation
- •Results highlight breed differences in genetic associations with performance—findings from Standardbreds or Finnhorses cannot be directly applied to CBT breeding or training decisions
Key Findings
- •DMRT3 AA genotype showed no significant association with precocity (performance at 3 years) in Coldblooded trotters, unlike in other harness racing breeds
- •Only race time and disqualifications differed by genotype at age 3, with AA horses fastest but CC horses more frequently disqualified
- •AA genotype frequency was significantly lower in raced versus unraced CBTs, with less than 50% of AA horses participating in races
- •AA genotype did not demonstrate superior performance in any age interval (3, 3-6, or 7-10 years) in this breed