Table 2 Phenotypic differences between individuals in the sequenced sample with two copies of the RELN reference haplotype (rr genotype) and those with two copies of the RELN alternative haplotype (RR genotype). Differences were estimated using a general linear model with sex as a fixed effect. The table presents the number of observations (N), minimum (min) and maximum (max) phenotypic scores, least squares means (lsmeans) with standard errors (se), and p-values for lsmean differences between the rr and RR genotypes. Age at assessment was recorded in years. Traits Tölt, Slow tölt, Trot, Pace, Gallop, Canter, and Back and croup were scored subjectively on a scale from 5.0 to 10. The trait Pace ≥ 5.0 includes all Pace scores, including 5.0 (indicating the trait was not shown), whereas Pace > 5.0 includes only scores for which the trait was shown. Morphological traits, including Height at front and Backline, were measured in centimeters. Height at front is defined as the difference between the highest point on the withers (M1) and the tuber sacrale (M3), while Backline is defined as the difference between the height at the tuber sacrale (M3) and the lowest point of the back (M2).

From: Genetic influence of a STAU2 frameshift mutation and RELN regulatory elements on performance in Icelandic horses