McAnany J Jason, Alexander Kenneth R, Kumar Nalin M, Ying Hongyu, Anastasakis Anastasios, Fishman Gerald A
Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, Chicago, IL 60612, USA.
Ophthalmic Genet. 2013 Sep;34(3):167-73. doi: 10.3109/13816810.2012.743570. Epub 2013 Jan 4.
To document a novel NYX gene mutation in a patient with X-linked complete congenital stationary night blindness and to describe this patient's electroretinogram (ERG) characteristics.
ERGs were recorded from a 17-year-old male with a previously unreported NYX mutation (819G > A) that results in a missense codon change (Trp237Ter). ERGs were recorded in response to brief-flash stimuli, 6.33-Hz sawtooth flicker, and sinusoidal flicker ranging from 6.33-100 Hz. The omitted stimulus response (OSR) of the flicker ERG, which is thought to be generated within the ON-pathway, was also assessed.
The patient's single-flash responses were consistent with previously documented NYX ERG characteristics, including a high-luminance flash response that was electronegative under dark-adapted conditions and a square-like a-wave followed by an abnormally shaped positive potential under light-adapted conditions, both of which are consistent with an ON-pathway deficit. Further evidence for an ON-pathway deficit included: (1) ERGs to rapid-on sawtooth flicker in which b-wave amplitude was reduced more than a-wave amplitude, and (2) responses to sinusoidal flicker that lacked the normal amplitude minimum and phase inflection near 12 Hz, ERG characteristics that are like those of patients with other NYX mutations. Novel findings included a pronounced amplitude attenuation for sinusoidal flicker at frequencies above approximately 50 Hz and an absent OSR, suggesting ON-pathway dysfunction at high frequencies.
The substantial loss of ERG amplitude and apparent ON-pathway dysfunction at high temporal frequencies distinguish this patient with a Trp237Ter NYX mutation from those with other previously reported NYX mutations.
记录一名患有X连锁完全性先天性静止性夜盲症患者的新型NYX基因突变，并描述该患者的视网膜电图（ERG）特征。
对一名17岁男性进行ERG记录，该男性具有先前未报道的NYX突变（819G>A），该突变导致错义密码子改变（Trp237Ter）。记录ERG对短暂闪光刺激、6.33Hz锯齿状闪烁以及6.33 - 100Hz正弦闪烁的反应。还评估了闪烁ERG的遗漏刺激反应（OSR），其被认为是在ON通路内产生的。
患者的单次闪光反应与先前记录的NYX ERG特征一致，包括在暗适应条件下高亮度闪光反应为负电位，以及在明适应条件下呈方形的a波后跟随异常形状的正电位，这两者均与ON通路缺陷一致。ON通路缺陷的进一步证据包括：（1）对快速开启锯齿状闪烁的ERG，其中b波振幅比a波振幅降低更多；（2）对正弦闪烁的反应在12Hz附近缺乏正常的振幅最小值和相位拐点，这些ERG特征与其他NYX突变患者的特征相似。新发现包括在约50Hz以上频率的正弦闪烁中明显的振幅衰减以及OSR缺失，提示高频下ON通路功能障碍。
该Trp237Ter NYX突变患者与其他先前报道的NYX突变患者不同，其ERG振幅大幅降低以及在高时间频率下明显的ON通路功能障碍。
