Transmission ratio distortion detection by neutral genetic markers in the Pura Raza Española horse breed.

The research investigates a genetic anomaly known as Transmission Ratio Distortion (TRD) in the Pura Raza Española horse breed. The study identifies specific regions of TRD using neutral genetic markers and proposes further understanding of its impact on horse breeding programs.

Research Methodology

• The researchers studied TRD in a huge sample size of 126,394 trios consisting of a stallion, mare, and their offspring. Each trio was genotyped using a panel of 17 neutral microsatellite markers as recommended by the International Society for Animal Genetics for paternity tests and individual identification.
• The neutral genetic markers used in the study had a varying number of alleles, ranging from 13 to 18, and the total number of alleles investigated was 268.
• The TRDscan v.2.0 software was employed to identify regions with distorted segregation ratios, thus pointing out potential areas of TRD.

Findings of the Study

• The study successfully identified a total of 12 decisive alleles (out of 11 microsatellites) for genotypic TRD. Out of these, 3 and 9 followed additive and heterosis patterns respectively.
• A further 19 alleles (out of 10 microsatellites) were determined to display allelic TRD. 14 of these were parent-unspecific while 5 were specifically associated with the stallion-mare.
• The analysis also identified and annotated 24 genes within the TRD regions which were mostly associated with cholesterol metabolism and homeostasis. These annotated genes could potentially be linked to various non-specific health issues like impaired fertility, stunted growth, and compromised overall health.

Implications and Further Research

• The study suggests that TRD can have a significant impact on the inheritance of certain genetic traits in horses, specifically in the Pura Raza Española breed.
• These findings may potentially alter horse breeding strategies once a better understanding of the TRD and its impact is attained.
• However, the researchers concede that further analysis and validation are needed before these results can be effectively utilized in horse breeding programme strategies.