Genotype concordance and trait mapping efficacy comparing data from the Equine 670 K SNP array with whole genome sequence in 21 horses

With advancing genomic technologies, single-nucleotide polymorphism (SNP) arrays and whole genome sequencing (WGS) have become essential tools in equine genetic research. In this study, we assessed the concordance in SNP calls and trait-mapping efficacy by comparing data of 21 horses both genotyped on the Equine 670 K SNP array and sequenced at either ~12× or ~30× depth. Our analysis revealed that higher sequencing depths were significantly associated with fewer discordant calls between platforms. Additionally, we investigated the most frequent no-call and discordant positions and identified positions that were indels or multiallelic in the WGS. To assess the effectiveness of the 670 K SNP array vs. WGS in trait association studies, we mapped the chestnut coat color. Both technologies showed a clear peak at the expected locus, although neither association had loci reaching Bonferroni-corrected statistical significance, which was not statistically possible in this small group of horses. The findings of this study provide valuable insights for making informed decisions when selecting between SNP arrays and WGS at varying sequencing depths for equine genomic research applications.