Jørgensen Dina, Ropstad Ernst-Otto, Meuwissen Theodorus, Lingaas Frode
Medical Genetics Unit, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, P.O. box 5003, 1432, Ås, Norway.
Evidensia Oslo Dyresykehus, Ensjøveien 14, 0655, Oslo, Norway.
Canine Med Genet. 2023 Jul 24;10(1):9. doi: 10.1186/s40575-023-00132-1.
Distichiasis is a condition characterized by aberrant hairs along the eyelid margins. The symptoms are usually mild but can lead to ulcerations and lesions of the cornea in severe cases. It is the most frequently noted ocular disorder in Norwegian Staffordshire bull terriers (SBT), with a prevalence above 18% in the adult population. A complex inheritance is assumed, but there is sparse knowledge about the genetic background of distichiasis in dogs. We have performed a genome-wide association study of distichiasis in SBT and used genomic data in an attempt to predict genomic values for the disorder.
We identified four genetic regions on CFA1, CFA18, CFA32 and CFA34 using a mixed linear model association analysis and a Bayesian mixed model analysis. Genomic values were predicted using GBLUP and a Bayesian approach, BayesR. The genomic prediction showed that the 1/4 of dogs with predicted values most likely to acquire distichiasis had a 3.9 -4.0 times higher risk of developing distichiasis compared to the quarter (1/4) of dogs least likely to acquire the disease. There was no significant difference between the two methods used.
Four genomic regions associated with distichiasis were discovered in the association analysis, suggesting that distichiasis in SBT is a complex trait involving numerous loci. The four associated regions need to be confirmed in an independent sample. We also used all 95 K SNPs for genomic prediction and showed that genomic prediction can be a helpful tool in selective breeding schemes at breed level aiming at reducing the prevalence of distichiasis in SBTs in the future, even if the predictive value of single dogs may be low.
双行睫是一种以眼睑边缘出现异常毛发为特征的病症。症状通常较轻，但在严重情况下可导致角膜溃疡和病变。它是挪威斯塔福郡斗牛梗（SBT）中最常见的眼部疾病，成年犬群中的患病率超过18%。推测其遗传方式复杂，但关于犬类双行睫的遗传背景知之甚少。我们对SBT的双行睫进行了全基因组关联研究，并使用基因组数据试图预测该疾病的基因组值。
我们使用混合线性模型关联分析和贝叶斯混合模型分析，在犬1号染色体（CFA1）、犬18号染色体（CFA18）、犬32号染色体（CFA32）和犬34号染色体（CFA34）上鉴定出四个遗传区域。使用基因组最佳线性无偏预测法（GBLUP）和贝叶斯方法BayesR预测基因组值。基因组预测显示，预测值最有可能患双行睫的四分之一犬只，与最不可能患该病的四分之一犬只相比，患双行睫的风险高3.9至4.0倍。所用的两种方法之间没有显著差异。
在关联分析中发现了四个与双行睫相关的基因组区域，这表明SBT的双行睫是一个涉及众多基因座的复杂性状。这四个相关区域需要在独立样本中得到证实。我们还使用所有95K单核苷酸多态性（SNP）进行基因组预测，并表明基因组预测可以成为未来品种水平选择性育种计划中的一个有用工具，旨在降低SBT中双行睫的患病率，即使单只犬的预测价值可能较低。
