A genome-wide association study reveals loci influencing height and other conformation traits in horses.
Authors: Signer-Hasler Heidi, Flury Christine, Haase Bianca, Burger Dominik, Simianer Henner, Leeb Tosso, Rieder Stefan
Journal: PloS one
Summary
# Editorial Summary Genome-wide association studies have proven powerful tools for identifying genetic influences on economically important traits in horses, yet localising the specific genes responsible remains challenging even in large human populations. Researchers genotyped 1,077 Franches-Montagnes horses using approximately 40,000 SNPs to map quantitative trait loci (QTL) affecting height at withers and related conformation characteristics. Two major loci were identified on chromosomes 3 and 9, located near LCORL/NCAPG and ZFAT genes respectively—both previously implicated in human height regulation—together accounting for roughly 18.2% of the heritable variation in withers height. Notably, the chromosome 3 region showed pleiotropic effects, influencing not only height but also leg conformation, mandibular shape, gait quality and head expression, whilst the chromosome 9 locus additionally affected croup and back length. For breeding programmes and genetic selection in horses, these findings offer molecular markers for height and conformation prediction; however, the substantial "missing heritability" (particularly the unexplained 11% contribution from chromosome 1) indicates that many additional loci of smaller effect likely remain to be discovered, emphasising the polygenic nature of these traits and the limitations of genomic prediction from current SNP panels alone.
Read the full abstract on PubMed
Practical Takeaways
- •Height and conformation traits in horses are controlled by identifiable genetic loci, with chromosome 3 and 9 regions being primary contributors to selective breeding decisions
- •Multiple conformation traits are genetically linked through pleiotropy (single genes affecting multiple traits), so selection for height may simultaneously modify leg conformation and gait quality
- •Genetic testing for SNPs near LCORL/NCAPG and ZFAT genes could support breeding selection for desired conformation traits in Franches-Montagnes and related breeds
Key Findings
- •Two major QTL for height at withers identified on chromosomes 3 and 9, explaining 18.2% of heritable variation in Franches-Montagnes horses
- •QTL on chromosome 3 near LCORL/NCAPG genes associated with multiple traits including leg conformation, gait correctness, and head expression
- •QTL on chromosome 9 near ZFAT gene associated with wither height, croup length, and back length
- •Chromosome 1 accounts for 11% of height variance despite lack of significant SNP associations, indicating additional unmapped genetic factors