College of Animal Science & Technology, China Agricultural University, Beijing, China.
PLoS One. 2010 Feb 24;5(2):e9410. doi: 10.1371/journal.pone.0009410.
Canine Hip Dysplasia (CHD) is a common inherited disease that affects dog wellbeing and causes a heavy financial and emotional burden to dog owners and breeders due to secondary hip osteoarthritis. The Orthopedic Foundation for Animals (OFA) initiated a program in the 1960's to radiograph hip and elbow joints and release the OFA scores to the public for breeding dogs against CHD. Over last four decades, more than one million radiographic scores have been released.
METHODOLOGY/PRINCIPAL FINDINGS: The pedigrees in the OFA database consisted of 258,851 Labrador retrievers, the major breed scored by the OFA (25% of total records). Of these, 154,352 dogs had an OFA hip score reported between 1970 and 2007. The rest of the dogs (104,499) were the ancestors of the 154,352 dogs to link the pedigree relationships. The OFA hip score is based on a 7-point scale with the best ranked as 1 (excellent) and the worst hip dysplasia as 7. A mixed linear model was used to estimate the effects of age, sex, and test year period and to predict the breeding value for each dog. Additive genetic and residual variances were estimated using the average information restricted maximum likelihood procedure. The analysis also provided an inbreeding coefficient for each dog. The hip scores averaged 1.93 (+/-SD = 0.59) and the heritability was 0.21. A steady genetic improvement has accrued over the four decades. The breeding values decreased (improved) linearly. By the end of 2005, the total genetic improvement was 0.1 units, which is equivalent to 17% of the total phenotypic standard deviation.
CONCLUSION/SIGNIFICANCE: A steady genetic improvement has been achieved through the selection based on the raw phenotype released by the OFA. As the heritability of the hip score was on the low end (0.21) of reported ranges, we propose that selection based on breeding values will result in more rapid genetic improvement than breeding based on phenotypic selection alone.
犬髋关节发育不良（CHD）是一种常见的遗传性疾病，会影响犬只的健康，并因继发髋关节骨关节炎给犬主和繁殖者带来沉重的经济和情感负担。动物骨科基金会（OFA）在 20 世纪 60 年代启动了一项计划，对髋关节和肘关节进行放射照相，并向公众发布 OFA 评分，以选择对抗 CHD 的繁殖犬。在过去的四十年中，已经发布了超过一百万个放射照相评分。
方法/主要发现：OFA 数据库中的系谱由 258851 只拉布拉多猎犬组成，这是 OFA 评分的主要品种（占总记录的 25%）。在这些狗中，有 154352 只狗在 1970 年至 2007 年间报告了 OFA 髋关节评分。其余的狗（104499 只）是 154352 只狗的祖先，用于链接系谱关系。OFA 髋关节评分基于 7 分制，最好的评为 1（优秀），最差的髋关节发育不良评为 7。使用混合线性模型来估计年龄、性别和测试年份期间的影响，并预测每只狗的繁殖价值。使用平均信息约束最大似然程序估计加性遗传和残差方差。该分析还为每只狗提供了一个近交系数。髋关节评分平均为 1.93（+/-SD=0.59），遗传力为 0.21。在过去的四十年中，遗传改良一直在稳步进行。繁殖值呈线性下降。到 2005 年底，总遗传改良为 0.1 个单位，相当于总表型标准差的 17%。
结论/意义：通过基于 OFA 发布的原始表型进行选择，已经实现了稳定的遗传改良。由于髋关节评分的遗传力处于报告范围的低端（0.21），我们建议基于繁殖值的选择将比仅基于表型选择的繁殖产生更快的遗传改良。
