Research Article Allelic and genotypic frequencies of the <i>DMRT3</i> gene in the Brazilian horse breed Mangalarga Marchador and their association with types of gait

Abstract

The DMRT3 gene has been described as the main gene influencing gait in horses; however, most studies have examined its effects by comparing information from trotted and gaited individuals. Within the Brazilian Mangalarga Marchador breed, animals can present two types of gaits (marcha batida and marcha picada), which differ in the movement form-diagonal (marcha batida) or lateral (marcha picada). We examined a possible association of the g.22999655C>A DMRT3 SNP with the type of gait, in this two-gaits breed. The relationship between individuals was calculated for the two phenotypic groups, as well as the inbreeding coefficient and its trend over generations. The allelic and genotypic frequencies were estimated based on genotype data from 310 horses (205 marcha ©FUNPEC-RP www.funpecrp.com.br Genetics and Molecular Research 18 (1): gmr18217 F.O. Bussiman et al. 2 batida; 105 marcha picada).Two threshold models were used to determine the proportion of phenotypic variance explained by DMRT3 genotypes. The average coancestry for animals with marcha batida was 0.04 ± 0.00, whereas in marcha picada it was 0.05 ± 0.01 (higher than the population mean of 0.04 ± 0.00). The inbreeding coefficient was 1.71% and 3.48% for marcha batida and marcha picada animals, respectively. Effects of the DMRT3 gene ranged from 9.94 to 10.77% (as a proportion of phenotypic variance) when included as an uncorrelated random effect and as a covariable, respectively. The genotypic frequencies of the DMRT3 and the patterns of kinship and inbreeding could be a result of selection in this breed, resulting in statistical confusion between the DMRT3 effects and population structure.

Fine‐scale estimation of inbreeding rates, runs of homozygosity and genome‐wide heterozygosity levels in the Mangalarga Marchador horse breed

“…Recently, in the MM was suggested polygenic control over gait types, corroborating with the findings of Patterson, Staiger, and Brooks (2015) and Fonseca, Ferraz, Lage, Pereira, and Curi (2017) (see Bussiman et al., 2019). In addition, several candidate genes have been identified and associated with signatures of selection for both gait types (Santos, 2020).…”

“…Studying pedigree representation in a genome‐wide association study in MM, Bussiman et al. (2019) reported that familiar structures are very common in horses, probably associated with a mating system based on the intense use of specific animals that achieve more awards in competitions.…”

Genome-wide scans for signatures of selection in Mangalarga Marchador horses using high-throughput SNP genotyping

“…The gaits are generally considered to be discrete patterns of footfalls and are divided into symmetrical and asymmetrical [ 27 ]. The allele A of the DMRT3 gene is only related to the picada gait in the MM, with two genotypes AA and CA, while the genotype CC is related to batida gait [ 28 ]; however, some studies have shown gait ability (the lateral gait pattern) is under the influence of a set of genes [ 5 , 29 ]. Other discoveries suggested that alleles related to the type of gait were differently fixed within each gait type [ 5 ].…”

Genomic analysis of gaits and racing performance of the French trotter

“…However, there has been an established relationship between genotype at DMRT3 and the ability to pace (Han & Peñagaricano, 2016). For alternative gaits such as marcha batida, marcha picada in Brazilian Mangalarga Marchador horses (Bussiman et al., 2019, 2020; Fonseca et al., 2017; Patterson et al., 2015), rack and slow gait in American Saddlebred horses (Regatieri et al., 2016), Tölt in Icelandic horse (Fegraeus, Hirschberg, et al., 2017; Jaderkvist et al., 2015; Kristjansson et al., 2014), and Trocha and Colombian trot in Colombian horses (Novoa‐Bravo et al., 2018), the relationship with DMRT3 genotype was not so obvious and many other markers were found. We had attempted to predict the DMRT3 genotype using only the knowledge of trotting technique and failed, even if a strong difference in genotype frequency was found between main trotting technique characteristics.…”