Kim E-S, Berger P J, Kirkpatrick B W
Department of Animal Sciences, University of Wisconsin, Madison, WI 53706, USA.
Anim Genet. 2009 Jun;40(3):300-7. doi: 10.1111/j.1365-2052.2008.01832.x. Epub 2009 Feb 10.
Twinning is a complex trait with negative impacts on health and reproduction, which cause economic loss in dairy production. Several twinning rate quantitative trait loci (QTL) have been detected in previous studies, but confidence intervals for QTL location are broad and many QTL are unreplicated. To identify genomic regions or genes associated with twinning rate, QTL analysis based on linkage combined with linkage disequilibrium (LLD) and individual marker associations was conducted across the genome using high-throughput single nucleotide polymorphism (SNP) genotypes. A total of 9919 SNP markers were genotyped with 200 sires and sons in 19 half-sib North American Holstein dairy cattle families. After SNPs were genotyped, informative markers were selected for genome-wide association tests and QTL searches. Evidence for twinning rate QTL was found throughout the genome. Thirteen markers significantly associated with twinning rate were detected on chromosomes 2, 5 and 14 (P < 2.3 x 10(-5)). Twenty-six regions on fourteen chromosomes were identified by LLD analysis at P < 0.0007. Seven previously reported ovulation or twinning rate QTL were supported by results of single marker association or LLD analyses. Single marker association analysis and LLD mapping were complementary tools for the identification of putative QTL in this genome scan.
双胎妊娠是一种复杂性状，对健康和繁殖有负面影响，会给奶牛生产带来经济损失。在以往研究中已检测到几个双胎率数量性状基因座（QTL），但QTL定位的置信区间较宽，且许多QTL未得到重复验证。为了鉴定与双胎率相关的基因组区域或基因，利用高通量单核苷酸多态性（SNP）基因型在全基因组范围内进行了基于连锁分析结合连锁不平衡（LLD）和单个标记关联的QTL分析。对19个北美荷斯坦奶牛半同胞家系中的200头父系和子代进行了基因分型，共检测了9919个SNP标记。在对SNP进行基因分型后，选择信息性标记用于全基因组关联测试和QTL搜索。在全基因组中均发现了双胎率QTL的证据。在2号、5号和14号染色体上检测到13个与双胎率显著相关的标记（P < 2.3×10⁻⁵）。通过LLD分析在14条染色体上鉴定出26个区域，P < 0.0007。单标记关联分析或LLD分析的结果支持了7个先前报道的排卵或双胎率QTL。在本次基因组扫描中，单标记关联分析和LLD定位是鉴定假定QTL的互补工具。
