Kwok Jennifer C, Sato Yu, Niggel Jessica K, Ozdogan Emma, Murgiano Leonardo, Miyadera Keiko
Department of Clinical Sciences and Advanced Medicine, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
Vet Ophthalmol. 2024 Oct 20. doi: 10.1111/vop.13290.
Cone-rod dystrophy (cord1) is a form of progressive retinal atrophy. It is linked to an RPGRIP1 genetic variant which is the third most common canine disease variant thus far. While the variant affects various breeds, it is highly prevalent in English Springer Spaniels (ESSs). Yet its clinical and pathological implications remain equivocal. Herein, we study the retinal phenotype in ESSs genetically affected with the RPGRIP1 variant.
Over 4 years, 494 ESSs (123 affected) were enrolled.
PROCEDURE(S): Owner-perceived vision was collected via a questionnaire. Ophthalmic examination included fundus photography. In selected ESSs, retinal function and structure were assessed using electroretinography (ERG, 148 dogs) and optical coherence tomography (OCT, 4 dogs).
Ophthalmoscopic changes included peripheral hypo-reflective lesions often with distinct borders progressing centripetally culminating in generalized retinal atrophy. Cross-sectional study revealed declining photopic ERG amplitudes with age in the affected group but not in controls. OCT indicated progressive photoreceptor loss. Despite ophthalmoscopic, ERG, or OCT abnormalities, most affected dogs were not visually impaired per their owners. In a fraction of afflicted ESSs, vision/globe-threatening complications were documented including cataracts, lens luxation, and glaucoma.
In ESSs, the RPGRIP1 variant is associated with insidious pathology with delayed-onset visual defects. The subtle phenotype without apparent visual deficit until the final years of life, if at all, may have caused underdiagnosis of cord1. Still, DNA testing remains informative, and ERG and OCT indicate progressive pathology. Peripheral fundus examination and photopic ERG are particularly useful for early detection and monitoring of cord1.
锥杆营养不良（cord1）是一种进行性视网膜萎缩形式。它与RPGRIP1基因变异有关，该变异是迄今为止第三常见的犬类疾病变异。虽然该变异影响多种犬种，但在英国激飞猎犬（ESSs）中高度流行。然而，其临床和病理意义仍不明确。在此，我们研究了遗传上受RPGRIP1变异影响的ESSs的视网膜表型。
在4年多的时间里，纳入了494只ESSs（123只患病）。
通过问卷收集主人感知到的视力情况。眼科检查包括眼底摄影。在选定的ESSs中，使用视网膜电图（ERG，148只犬）和光学相干断层扫描（OCT，4只犬）评估视网膜功能和结构。
眼底镜检查变化包括周边低反射性病变，通常边界清晰，向心性进展，最终导致广泛性视网膜萎缩。横断面研究显示，患病组的明视ERG振幅随年龄下降，而对照组则无此现象。OCT显示光感受器逐渐丧失。尽管有眼底镜、ERG或OCT异常，但大多数患病犬的主人并未发现其视力受损。在一部分患病的ESSs中，记录到了威胁视力/眼球的并发症，包括白内障、晶状体脱位和青光眼。
在ESSs中，RPGRIP1变异与隐匿性病理改变及延迟出现的视觉缺陷有关。这种直到生命最后几年（如果有影响的话）才出现明显视觉缺陷的微妙表型可能导致了cord1的诊断不足。尽管如此，DNA检测仍然具有参考价值，ERG和OCT表明存在进行性病理改变。周边眼底检查和明视ERG对cord1的早期检测和监测特别有用。
