Purchase this article with an account.
A. Omar, J. Racine, I. Lopez, V. J. Conte, J. Galic, A. den Hollander, R. K. Koenekoop; Finding the Causal Gene for Pericentral Retinitis Pigmentosa. Invest. Ophthalmol. Vis. Sci. 2010;51(13):4084.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Pericentral retinitis pigmentosa (PCRP) is a peculiar subtype of RP as photoreceptor death is confined to a well-defined retinal region, while inside and outside of this circle of cell-death, photoreceptors are viable, despite carrying the mutation. Discovering the causal gene for PCRP will advance our understanding of retinal patterning, photoreceptor biology and retinal genetics. We identified a consanguineous Lebanese pedigree with PCRP and aim to identify this gene using whole genome scanning.
We measured projected Snellen acuities, rod- and cone- ERGs (Diagnosys LLC), multifocal ERGs (mfERGs) (Electrodiagnostic Imaging Inc), retinal photography (Canon CR-1 Mark II), in vivo microscopy and fundus autofluorescence (AF) (Spectralis OCT, Heidelberg), and kinetic perimetry (Goldmann visual fields) (GVF). DNA was collected with informed consents. SNP genotyping was done with the Illumina Ultra High-Throughput Bead Lab Technology.
Affected members had typical pericentral scotomas from 2-20 degrees and acuities from 20/60-20/100. The rod mediated ERG was non-detectable, while a 10 uV cone-mediated ERG could still be recorded. The morphology was abnormal due to the absence of OP3 on the ascending limb of the b-wave. MfERGs were more preserved centrally than peripherally. Fundal exam, OCT and AF showed concentric rings of abnormalities. We found a normal appearing disc and posterior pole, narrow arterioles and marked beaten metal along the arcades. We also found a striking deposit of hyperfluorescent material between the outer segments (OS) and the RPE and a prominent AF pattern of grainy hyperfluorescence in the posterior pole. SNP genotyping identified eight large homozygous regions ranging from 6-41 Mb in the proband. SNP genotyping of the other affected sibs allowed us to reduce and narrow the number of significant intervals to three small regions (chrom. 2, 20, 4), and we are screening other PCRP families, to test the locus heterogeneity hypothesis.
SNP genotyping identified three novel intervals, none of which overlap with known loci or genes for RP. Thus, PCRP is a unique form of RP with its own novel genetic cause. We identified concentric structural changes centered on the fovea with progressive outer nuclear layer loss towards the periphery and marked lipofuscin accumulation between the OS and RPE. The causal gene is likely involved in these pathological processes. Finding the PCRP gene will improve our understanding of both photoreceptor death and health.
This PDF is available to Subscribers Only