Abstract：
Characterized by the incomplete development of the germinal epithelium of the seminiferous tubules, Testicular hypoplasia (TH) leads to decreased sperm concentration, increased morphological changes in sperm and azoospermia. Economic losses resulting from the disposal of affected bulls reduce the efficiency of meat production systems. A genome-wide association study and functional analysis were performed to identify genomic windows and the underlying positional candidate genes associated with TH in Nellore cattle. Phenotypic and pedigree data from 207,195 animals and genotypes (461,057 single nucleotide polymorphism, SNP) from 17,326 sires were used in this study. TH was evaluated as a binary trait measured at 18 months of age. A possible correlated response on TH resulting from the selection for scrotal circumference was evaluated by using a two-trait analysis. Thus, estimated breeding values were calculated by fitting a linear-threshold animal model in a Bayesian approach. The SNP effects were estimated using the weighted single-step genomic BLUP method. Twelve non-overlapping windows of 20 adjacent SNP that explained more than 1% of the additive genetic variance were selected for candidate gene annotation. Functional and gene prioritization analysis of the candidate genes identified genes (KHDRBS3, GPX5, STAR, ERLIN2), which might play an important role in the expression of TH due to their known roles in the spermatogenesis process, synthesis of steroids and lipid metabolism.
摘要：
以生精小管的生发上皮不完全发育为特征，睾丸发育不全（TH）导致精子浓度降低，精子和无精子症的形态学变化增加。处置受影响的公牛造成的经济损失降低了肉类生产系统的效率。进行了全基因组关联研究和功能分析，以鉴定与Nellore牛中TH相关的基因组窗口和潜在的位置候选基因。来自207,195只动物和基因型的表型和谱系数据(461,057单核苷酸多态性，本研究使用了来自17,326个父系的SNP)。TH被评估为在18个月大时测量的二元性状。通过使用双性状分析评估了由阴囊周长选择引起的TH的可能相关响应。因此，通过在贝叶斯方法中拟合线性阈值动物模型来计算估计的育种值.使用加权单步基因组BLUP方法估计SNP效应。选择了20个相邻SNP的12个非重叠窗口，这些窗口解释了超过1％的加性遗传变异，用于候选基因注释。候选基因的功能和基因优先级分析鉴定的基因(KHDRBS3，GPX5，STAR，ERLIN2),由于它们在精子发生过程中的已知作用，它们可能在TH的表达中起重要作用，类固醇的合成和脂质代谢。
