Table 3.
The number of horses homozygous for the reference allele, heterozygous or homozygous for each P variant by phenotype and breed as well as the percentage of horses in each classification possessing each P variant and the variant allele frequencies
| N | Homozygous reference | Heterozygous | Homozygous Variant | % Horses Heterozygous or Homozygous Variant | Variant Allele Frequency | P‐value | ||
|---|---|---|---|---|---|---|---|---|
| Genotypic | Dominant | |||||||
| P2: MYOT‐ rs1138656462 | ||||||||
| Control‐WB | 54 | 46 | 7 | 1 | 15% | 0.08 | ||
| PSSM2/MFM‐WB | 68 | 50 | 16 | 2 | 27% | 0.15 | .32 | .23 |
| Control‐AR | 30 | 24 | 5 | 1 | 20% | 0.12 | ||
| PSSM2/MFM‐AR | 30 | 20 | 10 | 0 | 33% | 0.17 | .82 | 1.00 |
| P3a/P3b: FLNC‐ rs1139799323/ FLNC ‐ rs1142918816 | ||||||||
| Control‐WB | 54 | 49 | 5 | 0 | 9% | 0.05 | ||
| PSSM2/MFM‐WB | 68 | 60 | 8 | 0 | 12% | 0.06 | 1.00 | 1.00 |
| Control‐AR | 30 | 29 | 1 | 0 | 3% | 0.02 | ||
| PSSM2/MFM‐AR | 30 | 29 | 1 | 0 | 3% | 0.02 | 1.00 | 1.00 |
| P4: MYOZ3 ‐ rs1142544043 | ||||||||
| Control‐WB | 54 | 44 | 10 | 0 | 19% | 0.09 | ||
| PSSM2/MFM‐WB | 68 | 52 | 15 | 1 | 24% | 0.13 | 1.00 | .82 |
| Control‐AR | 30 | 26 | 4 | 0 | 13% | 0.07 | ||
| PSSM2/MFM‐AR | 30 | 24 | 5 | 1 | 20% | 0.12 | .61 | 1.00 |
P‐values are given for comparisons of the prevalence of the variant in PSSM2/MFM vs. controls using genotypic or dominant models. The predicted amino acid substitutions were based upon the variant positions and Ensembl transcript ENSECAT00000076596.1. There were no significant differences in the prevalence of the variants or allele frequencies between control and PSSM2/MFM horses of either breed.
Abbreviations: MFM, Myofibrillar Myopathy; PSSM2, Polysaccharide storage myopathy type 2.