Allele frequency of hereditary equine regional dermal asthenia in American Quarter horses in Brazil determined by quantitative real-time PCR with high resolution melting analysis.
Authors: Badial Peres R, Oliveira-Filho José P, Winand Nena J, Borges Alexandre S
Journal: Veterinary journal (London, England : 1997)
Summary
# Editorial Summary Hereditary equine regional dermal asthenia (HERDA) is a debilitating genetic condition affecting American Quarter horses, stemming from a specific missense mutation (c.115G>A) in the peptidylprolyl isomerase B gene that disrupts collagen cross-linking and causes progressive skin fragility and separation. Researchers in Brazil employed quantitative real-time PCR with high resolution melting analysis—a precise molecular genotyping technique—to screen a population sample of AQHs for this mutation, enabling rapid carrier identification without traditional sequencing delays. The study identified an allele frequency of 2.9% and carrier frequency of 5.8% within the Brazilian population studied, suggesting that roughly one in seventeen horses in that cohort carried at least one copy of the mutation. These findings have direct implications for stud book management and breeding programmes: whilst the prevalence appears lower than in some North American populations, the presence of carriers means HERDA remains a consideration for Quarter horse breeders in Brazil and potentially elsewhere in South America. The availability of this accurate molecular test allows breeding decisions to be made with confidence, enabling selective exclusion of carriers from breeding programmes to reduce disease incidence over successive generations.
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Practical Takeaways
- •Genetic testing for HERDA using high resolution melting PCR is now available to identify affected and carrier Quarter horses before breeding
- •Brazilian Quarter horse breeders should be aware that approximately 1 in 17 horses in this population may be a carrier, necessitating screening programs to reduce disease prevalence
- •This diagnostic tool enables informed breeding decisions to reduce the incidence of HERDA, a debilitating connective tissue disorder in the breed
Key Findings
- •A quantitative real-time PCR high resolution melting analysis assay successfully genotyped the c.115G>A missense mutation in the PPIB gene responsible for HERDA
- •HERDA allele frequency in Brazilian American Quarter horses was estimated at 2.9%
- •Carrier frequency for HERDA in the Brazilian AQH population was 5.8%