KCNV2基因新变异致3B型视锥细胞营养不良伴超正常视杆系统反应1例

Supernormal rod response mediated by a novel KCNV2 variant in a cone dystrophy type 3B patient

先证者为8岁男性患儿,双眼视力进行性下降3年,视网膜电图表现为独特的闪光视网膜电图波形,视杆和视锥系统反应下降;但暗适应状态高刺激强度时,视锥和视杆系统混合反应振幅“超正常”。基于靶向捕获(panel)的二代测序检测显示患儿KCNV2基因发生纯合非移码缺失变异c.1002‑1004del(p.L335del),患儿父亲携带该杂合变异。经生物信息分析,该变异具有致病性,诊断为视锥细胞营养不良3B型,即视锥细胞营养不良伴超正常视杆系统反应。

The proband was an 8‑year‑old boy,complaining of progressively decreased vision in both eyes for 3 years.The electroretinogram was characterized by supernormal rod response.While the responses of the rod and cone system were reduced,the amplitudes of dark‑adapted electroretinogram responses at a high intensity were supernormal.A homozygous non‑frameshift deletion variant c.1002‑1004del(p.L335del)in KCNV2 was found by the Next Generation Sequencing using a custom designed panel.His father was a heterozygous carrier of this variant.In silico analysis indicated the variant was harmful.The proband was diagnosed as cone dystrophy type 3B which also known as cone dystrophy with supernormal rod response.