Holl Heather, Isaza Ramiro, Mohamoud Yasmin, Ahmed Ayeda, Almathen Faisal, Youcef Cherifi, Gaouar Semir, Antczak Douglas F, Brooks Samantha
Department of Animal Sciences, UF Genomics Institute, University of Florida, Gainesville, FL 32610, USA.
Department of Small Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL 32608, USA.
Genes (Basel). 2017 Mar 9;8(3):102. doi: 10.3390/genes8030102.
While the typical Arabian camel is characterized by a single colored coat, there are rare populations with white spotting patterns. White spotting coat patterns are found in virtually all domesticated species, but are rare in wild species. Theories suggest that white spotting is linked to the domestication process, and is occasionally associated with health disorders. Though mutations have been found in a diverse array of species, fewer than 30 genes have been associated with spotting patterns, thus providing a key set of candidate genes for the Arabian camel. We obtained 26 spotted camels and 24 solid controls for candidate gene analysis. One spotted and eight solid camels were whole genome sequenced as part of a separate project. The spotted camel was heterozygous for a frameshift deletion in KIT (c.1842delG, named KITW1 for White spotting 1), whereas all other camels were wild-type (KIT+/KIT+). No additional mutations unique to the spotted camel were detected in the EDNRB, EDN3, SOX10, KITLG, PDGFRA, MITF, and PAX3 candidate white spotting genes. Sanger sequencing of the study population identified an additional five kITW1/KIT+ spotted camels. The frameshift results in a premature stop codon five amino acids downstream, thus terminating KIT at the tyrosine kinase domain. An additional 13 spotted camels tested KIT+/KIT+, but due to phenotypic differences when compared to the KITW1/KIT+ camels, they likely represent an independent mutation. Our study suggests that there are at least two causes of white spotting in the Arabian camel, the newly described KITW1 allele and an uncharacterized mutation.
虽然典型的阿拉伯骆驼的特征是单一颜色的皮毛，但也有罕见的种群具有白色斑点图案。白色斑点皮毛图案几乎在所有家养物种中都有发现，但在野生物种中却很罕见。理论表明，白色斑点与驯化过程有关，并且偶尔与健康问题相关。尽管在各种各样的物种中都发现了突变，但与斑点图案相关的基因不到30个，因此为阿拉伯骆驼提供了一组关键的候选基因。我们获得了26只带斑点的骆驼和24只纯色对照骆驼用于候选基因分析。作为一个单独项目的一部分，对一只带斑点的骆驼和八只纯色骆驼进行了全基因组测序。这只带斑点的骆驼在KIT基因中存在一个移码缺失（c.1842delG，命名为KITW1表示白色斑点1），而所有其他骆驼都是野生型（KIT+/KIT+）。在EDNRB、EDN3、SOX10、KITLG、PDGFRA、MITF和PAX3候选白色斑点基因中未检测到带斑点骆驼特有的其他突变。对研究群体的桑格测序又鉴定出另外五只KITW1/KIT+带斑点的骆驼。这种移码导致在下游五个氨基酸处出现过早的终止密码子，从而在酪氨酸激酶结构域处终止KIT。另外13只带斑点的骆驼检测为KIT+/KIT+，但与KITW1/KIT+骆驼相比存在表型差异，它们可能代表一个独立的突变。我们的研究表明，阿拉伯骆驼白色斑点至少有两个原因，即新描述的KITW1等位基因和一个未鉴定的突变。
