Inheritance of hereditary equine regional dermal asthenia in Quarter Horses

Department of Animal Science, University of California, Davis, Davis, California, United States
American Journal of Veterinary Research (Impact Factor: 1.34). 04/2005; 66(3):437-42. DOI: 10.2460/ajvr.2005.66.437
Source: PubMed


To assess heritability and mode of inheritance for hereditary equine regional dermal asthenia (HERDA) in Quarter Horses.
1,295 horses with Quarter Horse bloodlines, including 58 horses affected with HERDA.
Horses were classified as affected or unaffected or as undetermined when data were insufficient to assess phenotype. Pedigree data were analyzed to determine the probable mode of inheritance. Heritability was estimated by use of Bayesian statistical methods.
Heritability (mean+/-SD) of HERDA was estimated to be 0.38+/-0.13, with both sexes having an equal probability of being affected. Results for evaluation of the pedigrees were consistent with a single Mendelian autosomal recessive mode of inheritance.
HERDA in Quarter Horses is an inherited disease, and affected horses are more likely to produce affected offspring. An autosomal recessive mode of inheritance should be considered by people making breeding decisions involving Quarter Horses when a first-degree relative has been confirmed with HERDA or has produced affected offspring. In addition, breeders whose horses have produced affected offspring can reduce the likelihood of producing affected horses in the future by avoiding inbreeding.

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    • "Although the mouse model recapitulates clinical features of the human disease, the phenotypes observed seem not to provide additional insights into the disease pathogenesis from what is already known of the disease affecting the human yet. Further, a missense G31R mutation in CyPB/PPIB was found in the horse to cause the degenerative skin disorder, HERDA, without changes in skeletal or collagen being reported (Tryon et al., 2005). Hence, additional studies are needed to understand what physiological substrate(s) are directly impaired by the loss of CyPB/PPIB function and promote disease pathogenesis. "
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    • "Hereditary equine regional dermal asthenia is an autosomal recessive dermatological condition of Quarter Horses and related crosses (Tryon et al. 2005). Though in some reports the condition has been referred to as " hyperelastosis cutis', this terminology has been discouraged as the defect does not appear to be in the elastic fibers (White et al. 2004). "
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    • "HERDA ist eine Krankheit, die vor allem bei Quarter Horses und verwandten Rassen beschrieben und die mit einer Mutation im PPIB Gen assoziiert ist (Scott und Miller, 2003; White et al., 2004; Tryon et al., 2005; Tyron et al., 2007). PPIB codiert die Peptidyl-Prolyl cis-trans-Isomerase (Synonym Cyclophilin B), ein essentielles Enzym für die Faltung der Pro--Ketten zum tripelhelikalen Prokollagen (Steinmann et al., 1991). "
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    ABSTRACT: Hereditäre equine dermale Asthenie (HERDA) ist eine autosomal rezessive Hautkrankheit, die vor allem junge Quarter Horses und verwandte Rassen betrifft. Die Symptome sind charakterisiert durch leichte Verletzbarkeit und erhöhte Dehnbarkeit der Haut, meist in der Satelllage. Die Prognose ist vorsichtig zu stellen, denn die Pferde können nicht normal zum Reiten eingesetzt werden und müssen oft euthanasiert werden. Beim Quarter Horse ist HERDA mit einer Mutation im Cyclophilin B Gen (PPIB) assoziiert. Cyclophilin B ist ein Enzym, welches für die Tripelhelixbildung von Kollagen wichtig ist. Wir beschreiben hier eine Schweizer Jährlings-Stute mit Symptomen von HERDA, aber ohne Mutation im PPIB Gen und bei der auch Ehlers-Danlos Typ IV, Typ VI, Typ VIIA, Typ VIIB und Typ VIIC (Dermatosparaxis) als ätiologische Ursache ausgeschlossen werden konnten. ABSTRACT: Hereditary equine dermal asthenia (HERDA) is an autosomal recessive skin disease that affects predominantly Quarter Horses and related breeds. Typical symptoms are easy bruising and hyperextensible skin on the back. The prognosis is guarded, as affected horses cannot be ridden normally and are often euthanised. In the Quarter Horse, HERDA is associated with a mutation in cyclophilin B (PPIB), an enzyme involved in triple helix formation of collagen. Here we describe the case of a Swiss Warmblood filly with symptoms of HERDA without PPIB-mutation and in which we also could exclude Ehlers-Danlos syndrome Type IV, VI, VIIA, VIIB and VIIC (dermatosparaxis type) as etiological diseases.
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