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Home / Equine Research Bank / Genomics / Homozygosity mapping approach identifies a missense mutation...
Genomics2007; 90(1); 93-102; doi: 10.1016/j.ygeno.2007.03.009

Homozygosity mapping approach identifies a missense mutation in equine cyclophilin B (PPIB) associated with HERDA in the American Quarter Horse.

Abstract: Hereditary equine regional dermal asthenia (HERDA), a degenerative skin disease that affects the Quarter Horse breed, was localized to ECA1 by homozygosity mapping. Comparative genomics allowed the development of equine gene-specific markers which were used with a set of affected horses to detect a homozygous, identical-by-descent block spanning approximately 2.5 Mb, suggesting a recent origin for the HERDA mutation. We report a mutation in cyclophilin B (PPIB) as a novel, causal candidate gene for HERDA. A c.115G>A missense mutation in PPIB alters a glycine residue that has been conserved across vertebrates. The mutation was homozygous in 64 affected horses and segregates concordant with inbreeding loops apparent in the genealogy of 11 affected horses. Screening of control Quarter Horses indicates a 3.5% carrier frequency. The development of a test that can detect affected horses prior to development of clinical signs and carriers of HERDA will allow Quarter Horse breeders to eliminate this debilitating disease.
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Publication Date: 2007-05-11 PubMed ID: 17498917DOI: 10.1016/j.ygeno.2007.03.009Google Scholar: Lookup
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  • Comparative Study
  • Journal Article
  • Research Support
  • Non-U.S. Gov't

Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

This research article discusses the identification of a particular mutation, namely a missense mutation in the gene equine cyclophilin B (PPIB), which is associated with a debilitating skin disease in Quarter Horses known as Hereditary equine regional dermal asthenia (HERDA). Through a method called homozygosity mapping, scientists were able to locate the mutation, which appears to have a recent origin. The findings pave the way for the development of a test to detect affected horses, which will help curb or eliminate the disease.

Key Findings

  • The research focused on the debilitating skin disease Hereditary equine regional dermal asthenia (HERDA) that affects Quarter Horses. Using a method called homozygosity mapping, which is designed to detect recessive mutations in dogs, they localised the degenerative skin disease to a particular region, ECA1, wherein they found a 2.5 Mb block that appeared to be homozygous and identical by descent (IBD) in affected horses. This indicates a recent origin for the HERDA mutation.
  • They identified a missense mutation, a type of mutation where a single nucleotide change results in a codon that codes for a different amino acid, in the gene equine cyclophilin B (PPIB). This particular mutation changes a glycine residue that is highly conserved across different vertebrates. This strongly suggests that the mutation in PPIB is the primary culprit for HERDA.
  • Screening of a control group of Quarter Horses apparently healthy showed a carrier frequency of 3.5%, signifying that this mutation is relatively common within this breed. As such, a considerable number of Quarter Horses could be quietly carrying the disease, and it can surface at any given moment causing harmful effects.

Implications and Future Directions

  • The identification of the missense mutation in PPIB affords the development of a potential diagnostic tool for HERDA. Equipped with this detection method, breeders would be able to screen their horses for this mutation before they show any signs of the disease. This early detection would prove significantly beneficial as it would allow the implementation of preventive measures to combat the debilitating illness.
  • The results of this research also pave the way to study the disease more closely and understand its exact etiology. This understanding could then be utilized to develop effective treatments and preventive measures, eventually leading to the eradication of the disease from the Quarter Horse breed.

Cite This Article

APA
Tryon RC, White SD, Bannasch DL. (2007). Homozygosity mapping approach identifies a missense mutation in equine cyclophilin B (PPIB) associated with HERDA in the American Quarter Horse. Genomics, 90(1), 93-102. https://doi.org/10.1016/j.ygeno.2007.03.009

Publication

Genomics
ISSN: 0888-7543
NlmUniqueID: 8800135
Country: United States
Language: English
Volume: 90
Issue: 1
Pages: 93-102

Researcher Affiliations

Tryon, Robert C
  • Department of Population Health and Reproduction, School of Veterinary Medicine, University of California-Davis, Davis, CA 9516, USA.
White, Stephen D
    Bannasch, Danika L

      MeSH Terms

      • Amino Acid Sequence
      • Animals
      • Asthenia / genetics
      • Asthenia / veterinary
      • Cyclophilins / genetics
      • Genome
      • Homozygote
      • Horse Diseases / genetics
      • Horses / genetics
      • Molecular Sequence Data
      • Mutation, Missense / genetics
      • Pedigree
      • Peptidylprolyl Isomerase / genetics
      • Physical Chromosome Mapping

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