Open AccessMixed Inheritance of Equine Recurrent Airway Obstruction
Author(s) -
Gerber V.,
Baleri D.,
KlukowskaRötzler J.,
Swinburne J.E.,
Dolf G.
Publication year - 2009
Publication title -
journal of veterinary internal medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.356
H-Index - 103
eISSN - 1939-1676
pISSN - 0891-6640
DOI - 10.1111/j.1939-1676.2009.0292.x
Subject(s) - warmblood , sire , polygene , major gene , heritability , inheritance (genetic algorithm) , genetics , genetic model , medicine , allele , biology , gene , quantitative trait locus , horse , zoology , paleontology
Background: Mode of inheritance of equine recurrent airway obstruction (RAO) is unknown. Hypothesis: Major genes are responsible for RAO. Animals: Direct offspring of 2 RAO‐affected Warmblood stallions (n = 197; n = 163) and a representative sample of Swiss Warmbloods (n = 401). Methods: One environmental and 4 genetic models (general, mixed inheritance, major gene, and polygene) were tested for Horse Owner Assessed Respiratory Signs Index (1–4, unaffected to severely affected) by segregation analyses of the 2 half‐sib sire families, both combined and separately, using prevalences estimated in a representative sample. Results: In all data sets the mixed inheritance model was most likely to explain the pattern of inheritance. In all 3 datasets the mixed inheritance model did not differ significantly from the general model ( P = .62, P = 1.00, and P = .27) but was always better than the major gene model ( P < .01) and the polygene model ( P < .01). The frequency of the deleterious allele differed considerably between the 2 sire families ( P = .23 and P = .06). In both sire families the displacement was large ( t = 17.52 and t = 12.24) and the heritability extremely large ( h 2 = 1). Conclusions and Clinical Relevance: Segregation analyses clearly reveal the presence of a major gene playing a role in RAO. In 1 family, the mode of inheritance was autosomal dominant, whereas in the other family it was autosomal recessive. Although the expression of RAO is influenced by exposure to hay, these findings suggest a strong, complex genetic background for RAO.