ArticleJournal of veterinary internal medicine
Allele Frequencies and Genotypes for the Ryanodine Receptor 1 Variant Causing Malignant Hyperthermia and Fatal Rhabdomyolysis With Hyperthermia in Horses.
Article in Journal of veterinary internal medicine. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 2 papers.
What it found
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Who cites it
2 citing papers in PubMed.
- Causal variants in animal genomes: approaches to identification, phenotypic impact, and implications for selective breeding.BMC genomics · 2026Review
- Equine models in translational medicine: A comparative approach to human health.Animal models and experimental medicine · 2026Review
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Authors and funding
3 authors.
Funding
Abstract
backgroundFatal anesthesia-induced malignant hyperthermia (MH) and rhabdomyolysis with hyperthermia documented in Quarter Horses (QH) breeds are caused by a missense variant in the ryanodine receptor 1 gene (RYR1: XP_023505430.1.:p.(R2454G), designated as MH). The reported cases to date have all been heterozygous, and the allele frequency is suspected to be low.
objectiveTo determine an accurate estimate of MH allele frequency in multiple horse breeds and investigate whether homozygous animals exist in the population. ANIMALS: In total, 159 227 horses from 16 breeds who were either submitted for clinical evaluation (n = 1500) or genetic testing (n = 157 727) were included.
methodsProspective study using banked DNA samples from two diagnostic laboratories determined the presence, zygosity, and estimated population MH allele frequencies.
resultsThe MH allele was exclusively detected in 391 QH, 18 Paints (PT), one Appaloosa (AP), and one QH-Clydesdale cross with similar allele frequencies (QH = 0.0013 and PT and AP = 0.0012). In cases submitted for clinical evaluation, death occurred as anesthesia-induced MH or severe acute rhabdomyolysis with hyperthermia (≥ 42°C, 107.6°F) in 51% of N/MH horses. Nineteen of the 20 fatal cases were young males (median: 9 years old, range: 9 months-14 years). No MH homozygotes were detected in either cohort evaluated. CONCLUSIONS AND CLINICAL IMPORTANCE: Homozygotes for the MH allele were not identified, and thus might be incompatible with life, but additional testing is needed to confirm. Although the allele frequency was low, being heterozygous poses a risk of death if anesthesia, stress, concurrent illness, breeding, or other stresses occur.
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