Abstract
Purpose:
To correlate the blue-on-yellow electroretinograms (B/Y ERG) to the genetic makeup of patients with enhanced S-cone syndrome (ESCS).
Methods:
We studied three Japanese men and one woman who were diagnosed with the ESCS based on results of clinical findings including the ISCEV-standard ERGs. B/Y ERGs were recorded with three-colored-light-emitting-diodes (LEDs) embedded in a contact-lens electrode. The blue LED stimulus was 50 cd/m2 and 2 msec., and the yellow background light was produced by a mixture of a red and a green LED (355 and 316 cd/m2). Genetic investigation of NR2E3 gene was also performed on all patients.
Results:
Case 1 was a 31-year-old man. The amplitude of b-wave of the B/Y ERG was approximately the same as that of the a-wave. Genetic investigation showed homozygous mutation of p.G51R in NR2E3 gene. Case 2 was a 78-year-old woman whose b-wave amplitude was approximately two-fold larger than that of the a-wave. Genetic investigation showed a compound heterozygous mutation of p.R48C and p.R104Q. Case 3 was a 11-year-old young man whose b-wave amplitude was also approximately two-fold larger than that of the a-wave. Genetic investigation showed a homozygous mutation of p.R104Q. Case 4 was a 35-year-old man whose b-wave amplitude was approximately the same as that of the a-wave. Genetic investigation showed a frame shift of c.919_920del2bp.
Conclusions:
These results suggest that the patients with ESCS may be divided into two groups; one shows supernormal b-wave and the other shows a negative b-wave in the B/Y ERGs. The exact relationship between the B/Y ERGs and mutations in the NR2E3 gene requires additional patients with ESCS.
Keywords: 509 electroretinography: clinical •
696 retinal degenerations: hereditary •
539 genetics