Abstract：
BACKGROUND: KCNV2-associated retinopathy causes a phenotype reported as \"cone dystrophy with nyctalopia and supernormal rod responses (CDSRR; OMIM# 610356),\" featuring pathognomonic findings on electroretinography (ERG). Here, we report the clinical courses of two siblings with CDSRR.
METHODS: Patient 1: A 3-year-old boy with intermittent exophoria was referred to our hospital. The patient\'s decimal best-corrected visual acuity (BCVA) at age 6 was 0.7 and 0.7 in the right and left eyes, respectively. Photophobia and night blindness were also observed. Because the ERG showed a delayed and supernormal b-wave with a \"squaring (trough-flattened)\" a-wave in the DA-30 ERG, and CDSRR was diagnosed. The patient\'s vision gradually worsened, and faint bilateral bull\'s eye maculopathy was observed at the age of 27 years, although the fundi were initially unremarkable. Genetic examination revealed a homozygous missense variant, c.529T > C (p.Cys177Arg), in the KCNV2 gene. Patient 2: The second patient was Patient 1\'s younger sister, who was brought to our hospital at 3 years of age. The patient presented with exotropia, mild nystagmus, photophobia, night blindness, and color vision abnormalities. The patients\' decimal BCVA at age 13 was 0.6 and 0.4 in the right and left eyes, respectively, and BCVA gradually decreased until the age of 24 years. The fundi were unremarkable. The siblings had similar ERG findings and the same homozygous missense variant in the KCNV2 gene.
CONCLUSIONS: The siblings had clinical findings typical of CDSRR. High-intense flash ERG is recommended for identifying pathognomonic \"squaring\" a-waves in patients with CDSRR.
METHODS: Patient 1: A 3-year-old boy with intermittent exophoria was referred to our hospital. The patient\'s decimal best-corrected visual acuity (BCVA) at age 6 was 0.7 and 0.7 in the right and left eyes, respectively. Photophobia and night blindness were also observed. Because the ERG showed a delayed and supernormal b-wave with a \"squaring (trough-flattened)\" a-wave in the DA-30 ERG, and CDSRR was diagnosed. The patient\'s vision gradually worsened, and faint bilateral bull\'s eye maculopathy was observed at the age of 27 years, although the fundi were initially unremarkable. Genetic examination revealed a homozygous missense variant, c.529T > C (p.Cys177Arg), in the KCNV2 gene. Patient 2: The second patient was Patient 1\'s younger sister, who was brought to our hospital at 3 years of age. The patient presented with exotropia, mild nystagmus, photophobia, night blindness, and color vision abnormalities. The patients\' decimal BCVA at age 13 was 0.6 and 0.4 in the right and left eyes, respectively, and BCVA gradually decreased until the age of 24 years. The fundi were unremarkable. The siblings had similar ERG findings and the same homozygous missense variant in the KCNV2 gene.
CONCLUSIONS: The siblings had clinical findings typical of CDSRR. High-intense flash ERG is recommended for identifying pathognomonic \"squaring\" a-waves in patients with CDSRR.
摘要：
背景：KCNV2相关的视网膜病变导致了一种表型，报告为“视锥细胞营养不良，伴有夜盲症和超正常的视杆反应（CDSRR；OMIM#610356），“以视网膜电图（ERG）的病理学发现为特征。这里,我们报告了两个患有CDSRR的兄弟姐妹的临床病程。
方法：患者1：一名3岁男孩因间歇性外隐症被转诊至我们医院。患者6岁时的十进制最佳矫正视力（BCVA）分别为0.7和0.7，分别。还观察到畏光和夜盲症。因为ERG在DA-30ERG中显示出延迟且超常的b波，具有“平方（波谷变平）”a波，并诊断为CDSRR。病人的视力逐渐恶化，在27岁时观察到微弱的双侧牛眼黄斑病变，尽管fundi最初并不引人注目。基因检查显示纯合错义变异,c.529T>C（p。Cys177Arg），KCNV2基因.病人2：第二个病人是病人1的妹妹，3岁时被带到我们医院.病人出现外斜视,轻度眼球震颤,畏光,夜盲症,和色觉异常。13岁时患者右眼和左眼的十进制BCVA分别为0.6和0.4，分别,BCVA逐渐下降，直到24岁。基金会并不引人注目。兄弟姐妹在KCNV2基因中具有相似的ERG发现和相同的纯合错义变体。
结论：兄弟姐妹有典型的CDSRR临床表现。建议使用高强度闪光ERG来识别CDSRR患者的病理信号“平方”a波。
方法：患者1：一名3岁男孩因间歇性外隐症被转诊至我们医院。患者6岁时的十进制最佳矫正视力（BCVA）分别为0.7和0.7，分别。还观察到畏光和夜盲症。因为ERG在DA-30ERG中显示出延迟且超常的b波，具有“平方（波谷变平）”a波，并诊断为CDSRR。病人的视力逐渐恶化，在27岁时观察到微弱的双侧牛眼黄斑病变，尽管fundi最初并不引人注目。基因检查显示纯合错义变异,c.529T>C（p。Cys177Arg），KCNV2基因.病人2：第二个病人是病人1的妹妹，3岁时被带到我们医院.病人出现外斜视,轻度眼球震颤,畏光,夜盲症,和色觉异常。13岁时患者右眼和左眼的十进制BCVA分别为0.6和0.4，分别,BCVA逐渐下降，直到24岁。基金会并不引人注目。兄弟姐妹在KCNV2基因中具有相似的ERG发现和相同的纯合错义变体。
结论：兄弟姐妹有典型的CDSRR临床表现。建议使用高强度闪光ERG来识别CDSRR患者的病理信号“平方”a波。
