Estimation of heritabilities, genetic correlations, and breeding values of four traits that collectively define hip dysplasia in dogs.
ABSTRACT OBJECTIVE-To estimate heritabilities and genetic correlations among 4 traits of hip joints (distraction index [DI], dorsolateral subluxation [DLS] score, Norberg angle [NA], and extended-hip joint radiograph [EHR] score) and to derive the breeding values for these traits in dogs. ANIMALS-2,716 dogs of 17 breeds (1,551 dogs in which at least 1 hip joint trait was measured). PROCEDURES-The NA was measured, and an EHR score was assigned. Hip joint radiographs were obtained from some dogs to allow calculation of the DI and DLS score. Heritabilities, genetic correlations, and breeding values among the DI, DLS score, NA, and EHR score were calculated by use of a set of multiple-trait, derivative-free, restricted maximum likelihood computer programs. RESULTS-Among 2,716 dogs, 1,411 (52%) had an estimated inbreeding coefficient of 0%; the remaining dogs had a mean inbreeding coefficient of 6.21%. Estimated heritabilities were 0.61, 0.54, 0.73, and 0.76 for the DI, DLS score, NA, and EHR score, respectively. The EHR score was highly genetically correlated with the NA (r = -0.89) and was moderately genetically correlated with the DI (r = 0.69) and DLS score (r = -0.70). The NA was moderately genetically correlated with the DI (r = -0.69) and DLS score (r = 0.58). Genetic correlation between the DI and DLS score was high (r = -0.91). CONCLUSIONS AND CLINICAL RELEVANCE-Establishment of a selection index that makes use of breeding values jointly estimated from the DI, DLS score, NA, and EHR score should enhance breeding programs to reduce the incidence of hip dysplasia in dogs.
Full-textDOI: · Available from: Zhiwu Zhang, Aug 27, 2014
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ABSTRACT: Genome-Wide Association Studies shed light on the identification of genes underlying human diseases and agriculturally important traits. This potential has been shadowed by false positive findings. The Mixed Linear Model (MLM) method is flexible enough to simultaneously incorporate population structure and cryptic relationships to reduce false positives. However, its intensive computational burden is prohibitive in practice, especially for large samples. The newly developed algorithm, FaST-LMM, solved the computational problem, but requires that the number of SNPs be less than the number of individuals to derive a rank-reduced relationship. This restriction potentially leads to less statistical power when compared to using all SNPs. We developed a method to extract a small subset of SNPs and use them in FaST-LMM. This method not only retains the computational advantage of FaST-LMM, but also remarkably increases statistical power even when compared to using the entire set of SNPs. We named the method SUPER (Settlement of MLM Under Progressively Exclusive Relationship) and made it available within an implementation of the GAPIT software package.PLoS ONE 09/2014; 9(9):e107684. DOI:10.1371/journal.pone.0107684 · 3.53 Impact Factor
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ABSTRACT: Background The inheritance of most human diseases and agriculturally important traits is controlled by many genes with small effects. Identifying these genes, while simultaneously controlling false positives, is challenging. Among available statistical methods, the mixed linear model (MLM) has been the most flexible and powerful for controlling population structure and individual unequal relatedness (kinship), the two common causes of spurious associations. The introduction of the compressed MLM (CMLM) method provided additional opportunities for optimization by adding two new model parameters: grouping algorithms and number of groups.ResultsThis study introduces another model parameter to develop an enriched CMLM (ECMLM). The parameter involves algorithms to define kinship between groups (that is, kinship algorithms). The ECMLM calculates kinship using several different algorithms and then chooses the best combination between kinship algorithms and grouping algorithms.Conclusion Simulations show that the ECMLM increases statistical power. In some cases, the magnitude of power gained by using ECMLM instead of CMLM is larger than the improvement found by using CMLM instead of MLM.BMC Biology 10/2014; 12(1):73. DOI:10.1186/s12915-014-0073-5 · 7.43 Impact Factor
Dataset: 20103409414[Show abstract] [Hide abstract]
ABSTRACT: This paper describes the results of Chiari osteotomy (CO) with simultaneous intertrochanteric osteotomy (IO) in dogs affected by bilateral hip dysplasia, score grade D. The dogs classified for the study were subjected to the following tests before and after surgery: abduction-external rotation test, hip extension test, dorso-lateral subluxation test (DLST), stand test, Ortolani sign, Barlow sign, measurements of the angle of flexion, angle of extension, angle of abduction, angle of adduction, and radiographic examinations determining the score grade for canine hip dysplasia in accordance with the scoring system recommended by the Fédération Cynologique Internationale. The test which most accurately reflected the post-operative improvement in patients was DLST where the negative response increased by 73% after CO and IO procedures. Changes in angle of inclination (AI) values were correlated with an improvement in hip functioning as a result of the administered treatment. The simultaneous application of CO and IO in dogs affected by hip dysplasia resulted in greater improvement of limb functioning in comparison with conventional IO.