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Safa Rahmani, Jason Comander, Carol Weigel DiFranco, Bernard Rosner, Michael A Sandberg; A Biomarker for Disease Course in Patients with Autosomal Dominant Retinitis Pigmentosa due to RHO Mutations. Invest. Ophthalmol. Vis. Sci. 2016;57(12):134.
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© 2017 Association for Research in Vision and Ophthalmology.
To determine whether the rate of decline of full-field cone electroretinogram (ERG) amplitude is related to baseline cone ERG amplitude or implicit time in patients with autosomal dominant retinitis pigmentosa (RP) with a Rhodopsin (RHO) gene mutation.
ERG recordings to 30-Hz full-field white flashes from 54 patients with autosomal dominant RP due to RHO mutations were analyzed retrospectively. Cone ERG responses were recorded in consecutive examinations separated by at least one year from the patient’s baseline (ages 8-66, 3-15 years of follow up). All had a delayed cone ERG implicit time at baseline (i.e., ≥ 33 msec). We used Stata 14 to perform repeated-measures longitudinal regression with loge amplitude as the dependent variable and time, quintile median loge baseline amplitude, quintile median baseline implicit time, and the cross products of time x quintile median loge baseline amplitude and time x quintile median baseline implicit time as the independent variables.
The mean exponential rate of amplitude decline over follow up was not significantly related to baseline amplitude. In contrast, for each increasing msec of baseline implicit time, the mean rate of amplitude decline accelerated by an average of 1.3%/year (p < 0.0001). The lowest quintile of baseline implicit time progressed at an average of 4.4%/year, while the highest quintile progressed at an average of 16.2%/year (Figure 1).
A more delayed baseline cone ERG implicit time predicts a faster rate of loss of cone ERG amplitude in RP patients with a RHO mutation. This finding may be useful to clinicians to help them advise patients about their future mobility handicap. It can also be useful for patient selection in clinical trials by limiting patients to those likely to have faster rates of progression, which should make it easier to detect a treatment difference over time and shorten clinical trials. Findings for patients with RHO mutations will also be compared with findings for patients with X-linked RP due to RPGR mutations and with findings for patients with autosomal recessive RP due to USH2A mutations.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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