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Discussion on Research Study: Genetic Predisposition to COPD (RAO)
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Moderator:
DrO
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Posted on Wednesday, Aug 26, 2009 - 3:53 am:
The idea of genetic predisposition to Heaves have been bantered before. This group of researchers found strong evidence for two different genetic predispositions to allergic pneumonitis.
DrO
J Vet Intern Med. 2009 May-Jun;23(3):626-30.
Mixed inheritance of equine recurrent airway obstruction.
Gerber V, Baleri D, Klukowska-Rötzler J, Swinburne JE, Dolf G.
Equine Clinic, Department of Veterinary Clinical Studies, University of Berne, Switzerland.
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.
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