Veterinary Genetics Laboratory, School of Veterinary Medicine, University of California-Davis, Davis, CA 95616, USA.
Bailly Vétérinaires Clinique du Lys, 77190 Dammarie-les-Lys, France.
Genes (Basel). 2020 Dec 5;11(12):1460. doi: 10.3390/genes11121460.
Squamous cell carcinoma (SCC) is the most common cancer affecting the equine eye. A missense variant within the gene damage-specific DNA binding protein 2 c.1013, p.Thr338Met) was previously identified as a causal recessive genetic risk factor for the development of ocular SCC within Haflingers, Belgian Draft horses, and Rocky Mountain Horses, but not in the Appaloosa or Arabian breeds. This study aimed to evaluate three cases of ocular SCC in additional breeds and determine if DNA testing for the DDB2 variant in warmblood horses and Connemara ponies is warranted. Histopathology confirmed ocular SCC in all three cases and DNA testing confirmed each horse was homozygous for the DDB2 risk factor. The DDB2 risk allele frequency was estimated to be 0.0043 for Holsteiners ( = 115), 0.014 for Belgian Warmbloods ( = 71), and 0.22 for Connemara Ponies ( = 86). Taken together these data support using DNA testing for DDB2 in Connemara Ponies to assist in mate selection and clinical management. Given the low observed allele frequencies in both the Holsteiner and Belgian Warmblood breeds and that the case under investigation was a warmblood cross-bred, evaluating additional SCC affected warmbloods is warranted to fully determine the importance of DDB2 genotyping as a risk factor in warmblood breeds.
鳞状细胞癌 (SCC) 是影响马眼部最常见的癌症。先前已鉴定出基因损伤特异性 DNA 结合蛋白 2 中的错义变体 (c.1013, p.Thr338Met) 是 Haflinger、比利时重型马和落基山马眼部 SCC 发展的隐性遗传风险因素，但在阿帕卢萨马和阿拉伯马中并非如此。本研究旨在评估其他品种中三例眼部 SCC，并确定是否有必要对温血马和康尼马拉小马的 DDB2 变体进行 DNA 检测。组织病理学在所有三种情况下均证实为眼部 SCC，DNA 检测证实每匹马均为 DDB2 风险因素的纯合子。DDB2 风险等位基因频率估计为荷斯坦马为 0.0043( = 115)，比利时温血马为 0.014( = 71)，康尼马拉小马为 0.22( = 86)。这些数据共同表明，在康尼马拉小马中使用 DDB2 的 DNA 检测来辅助选种和临床管理。鉴于荷斯坦马和比利时温血马两种品种中观察到的等位基因频率均较低，且被调查的病例为温血杂种，因此有必要评估其他受 SCC 影响的温血马，以充分确定 DDB2 基因分型作为温血马品种的风险因素的重要性。
