Extent and consistency across generations of linkage disequilibrium in commercial layer chicken breeding populations
Extent and consistency across generations of linkage disequilibrium in commercial layer chicken breeding populations
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DOI：
10.1534/genetics.105.040782
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发表时间：
2005-11-01
期刊：
影响因子：
3.3
通讯作者：
Soller, M
中科院分区：
文献类型：
--
作者：
Heifetz, EM;Fulton, JE;Soller, M
最近的研究报告了反刍家畜种群中令人惊讶的高度标记-标记连锁不平衡（LD）。这对QTL定位和标记辅助选择具有重要意义。本研究采用标准化卡方（X-2）测量方法对多个蛋鸡养殖群体的微卫星标记间的LD进行了评价。结果表明，在5 cM以内，标记间的LD显著降低，随着标记间距离的增加，LD迅速降低。5cm内的LD在世代间具有很强的保守性，且在染色体区域间存在差异。使用标记-标记间LD作为标记-QTL LD的指示，以中等功率对间隔2 cM的标记进行基因组扫描将有很好的机会发现这些群体中的大多数QTL分离。然而，在显示显著性状关联的标记中，预计只有57%的标记位于相关QTL的5厘米范围内，其余标记将在20厘米范围内。因此，QTL的高分辨率LD定位将需要在感兴趣的区域进行密集的标记基因分型，以允许QTL的间隔定位。
Recent studies report a surprisingly high degree of marker-to-marker linkage disequilibrium (LD) in ruminant livestock populations. This has important implications for QTL mapping and marker-assisted selection. This study evaluated LD between microsatellite markers in a number of breeding populations of layer chickens using the standardized chi-square (X-2') measure. The results show appreciable LD among markers separated by up to 5 cM, decreasing rapidly with increased separation between markers. The LD within 5 cM was strongly conserved across generations and differed among chromosomal regions. Using marker-to-marker LD as an indication for marker-QTL LD, a genome scan of markers spaced 2 cM apart at moderate power would have good chances of uncovering most QTL segregating in these populations. However, of markers showing significant trait associations, only 57% are expected to be within 5 cM of the responsible QTL, and the remainder will be up to 20 cM away. Thus, high-resolution LD mapping of QTL will require dense marker genotyping across the region of interest to allow for interval mapping of the QTL.