Nowacka-Woszuk J, Szczerbal I, Pausch H, Hundi S, Hytönen M K, Grzemski A, Flisikowski K, Lohi H, Switonski M, Szydlowski M
Department of Genetics and Animal Breeding, Poznan University of Life Sciences, Wolynska 33, 60-637, Poznan, Poland.
Chair of Animal Breeding, Technische Universitat Munchen, Liesel-Beckmann-Straße 1, D-85354, Freising-Weihenstephan, Germany.
Anim Genet. 2017 Jun;48(3):330-337. doi: 10.1111/age.12538. Epub 2017 Jan 17.
A disorder of sex development (DSD) in dogs with female sex chromosomes (78, XX), a lack of the SRY gene and the presence of testes or ovotestes is commonly diagnosed in numerous breeds. The molecular background of DSD is not fully recognized but has been linked to the copy number variation in the region harboring the SOX9 gene. We applied a genome-wide association study and targeted next-generation sequencing techniques to compare DSD and normal female dogs. The genome-wide association study did not indicate a significant chromosome region. Targeted next-generation sequencing of a 1.5-Mb region on canine chromosome 9 harboring the SOX9 gene revealed two putatively DSD-associated copy number variations 355 kb upstream and 691 kb downstream of SOX9, four blocks of low polymorphism and two blocks of an elevated heterozygosity. An initial next-generation sequencing analysis showed an association with two SNPs, but validation in larger cohorts did not confirm this result. We identified a large homologous fragment (over 243.8 kb), named hfMAGI2, located upstream of SOX9, that overlaps a known copy number variation region. It shows a high sequence similarity with the 5' flanking region of the MAGI2 gene located on canine chromosome 18 that encodes a protein involved in ovary formation during early embryonic development. Our study showed that the identified copy number variation region located upstream of the SOX9 gene contains potential regulatory sequences (long non-coding RNA and hfMAGI2) and led to the assumption that a multiplication of this element may alter expression of the SOX9 gene, triggering the DSD phenotype.
在具有雌性性染色体（78, XX）、缺乏SRY基因且存在睾丸或卵睾的犬类中，性发育障碍（DSD）在众多品种中普遍被诊断出来。DSD的分子背景尚未完全明确，但已与包含SOX9基因区域的拷贝数变异相关联。我们应用全基因组关联研究和靶向新一代测序技术来比较DSD犬和正常雌性犬。全基因组关联研究未表明有显著的染色体区域。对犬9号染色体上包含SOX9基因的1.5兆碱基区域进行靶向新一代测序，揭示了两个推测与DSD相关的拷贝数变异，分别位于SOX9上游355千碱基和下游691千碱基处，四个低多态性区域和两个杂合性升高区域。初步的新一代测序分析显示与两个单核苷酸多态性（SNP）相关，但在更大样本队列中的验证并未证实这一结果。我们在SOX9上游鉴定出一个大的同源片段（超过243.8千碱基），命名为hfMAGI2，它与一个已知的拷贝数变异区域重叠。它与位于犬18号染色体上的MAGI2基因的5'侧翼区域具有高度序列相似性，该基因编码一种在胚胎早期发育过程中参与卵巢形成的蛋白质。我们的研究表明，在SOX9基因上游鉴定出的拷贝数变异区域包含潜在的调控序列（长链非编码RNA和hfMAGI2），并由此推测该元件的倍增可能会改变SOX9基因的表达，从而引发DSD表型。
