Electroretinographic Findings in a Patient with Congenital Stationary Night Blindness Due to a Novel NYX Mutation. (September 2013)

• Record Type: Journal Article
• Authors: McAnany, J. Jason; Alexander, Kenneth R.; Kumar, Nalin M.; Ying, Hongyu; Anastasakis, Anastasios; Fishman, Gerald A.
• Is Part Of: Ophthalmic genetics. Volume 34:Number 3(2013:Sep.)
• Page Start: 167
• Page End: 173
• Publication Date: 2013-09
• Subjects: Eye -- Diseases -- Genetic aspects -- Periodicals; Eye Diseases -- genetics -- Periodicals; Eye Diseases -- in infancy & childhood -- Periodicals; 617.7
• DOI: 10.3109/13816810.2012.743570
• Languages: English
• ISSNs: 1381-6810

Abstract

<abstract> <title>ABSTRACT</title> <p> <italic>Purpose</italic>: To document a novel <italic>NYX</italic> gene mutation in a patient with X-linked complete congenital stationary night blindness and to describe this patient's electroretinogram (ERG) characteristics.</p> <p> <italic>Methods</italic>: ERGs were recorded from a 17-year-old male with a previously unreported <italic>NYX</italic> 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.</p> <p> <italic>Results</italic>: The patient's single-flash responses were consistent with previously documented <italic>NYX</italic> 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 <italic>NYX</italic> 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.</p> <p> <italic>Conclusion</italic>: The substantial loss of ERG amplitude and apparent ON-pathway dysfunction at high temporal frequencies distinguish this patient with a Trp237Ter <italic>NYX</italic> mutation from those with other previously reported <italic>NYX</italic> mutations.</p> </abstract>