Molecular Genetics Veterinary Service (SVGM), Department of Animal and Food Science, Veterinary School, Universitat Autònoma de Barcelona (UAB), 08193 Bellaterra, Barcelona, Spain.
BMC Genomics. 2011 Jul 1;12:339. doi: 10.1186/1471-2164-12-339.
Modern dog breeds display traits that are either breed-specific or shared by a few breeds as a result of genetic bottlenecks during the breed creation process and artificial selection for breed standards. Selective sweeps in the genome result from strong selection and can be detected as a reduction or elimination of polymorphism in a given region of the genome.
Extended regions of homozygosity, indicative of selective sweeps, were identified in a genome-wide scan dataset of 25 Boxers from the United Kingdom genotyped at 20,000 single-nucleotide polymorphisms (SNPs). These regions were further examined in a second dataset of Boxers collected from a different geographical location and genotyped using higher density SNP arrays (170,000 SNPs). A selective sweep previously associated with canine brachycephaly was detected on chromosome 1. A novel selective sweep of over 8 Mb was observed on chromosome 26 in Boxer and for a shorter region in English and French bulldogs. It was absent in 171 samples from eight other dog breeds and 7 Iberian wolf samples. A region of extended increased heterozygosity on chromosome 9 overlapped with a previously reported copy number variant (CNV) which was polymorphic in multiple dog breeds.
A selective sweep of more than 8 Mb on chromosome 26 was identified in the Boxer genome. This sweep is likely caused by strong artificial selection for a trait of interest and could have inadvertently led to undesired health implications for this breed. Furthermore, we provide supporting evidence for two previously described regions: a selective sweep on chromosome 1 associated with canine brachycephaly and a CNV on chromosome 9 polymorphic in multiple dog breeds.
现代犬种由于在品种创造过程中的遗传瓶颈和对品种标准的人工选择，表现出了一些品种特有的或少数品种共有的特征。基因组中的选择清扫是由于强烈的选择而产生的，可以检测到在基因组的特定区域中多态性的减少或消除。
在对来自英国的 25 只拳师犬进行全基因组扫描的数据集（约 20000 个单核苷酸多态性（SNP））中，发现了延伸的纯合区域，表明存在选择清扫。这些区域在来自不同地理位置的第二个拳师犬数据集（使用更高密度的 SNP 阵列进行基因分型（~170000 SNPs））中进行了进一步研究。在第 1 号染色体上检测到一个先前与犬短头畸形相关的选择清扫。在拳师犬和英国斗牛犬中，26 号染色体上观察到一个超过 8 Mb 的新的选择清扫，而在其他 8 个犬种的 171 个样本和 7 个伊比利亚狼样本中则不存在。9 号染色体上扩展的杂合性增加区域与先前报道的拷贝数变异（CNV）重叠，该 CNV在多个犬种中呈多态性。
在拳师犬基因组中发现了超过 8 Mb 的 26 号染色体上的选择清扫。这种清扫很可能是由于对感兴趣的特征进行了强烈的人工选择而导致的，这可能无意中导致了该品种的不良健康影响。此外，我们提供了两个先前描述的区域的支持证据：与犬短头畸形相关的 1 号染色体上的选择清扫和在多个犬种中呈多态性的 9 号染色体上的 CNV。
