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Emma Sara Duignan, Anthony G Robson, Elena Schiff, Genevieve Wright, Hannah Knight, Michel Michaelides, Andrew R Webster; The clinical and genetic characteristics of patients with biallelic RLBP1-mediated retinopathy. Invest. Ophthalmol. Vis. Sci. 2020;61(7):1952.
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© ARVO (1962-2015); The Authors (2016-present)
To characterise the genetic, clinical and electrophysiological features of RLBP1 retinopathy
Patients were identified through the Moorfields Eye Hospital electronic healthcare record. Fundus photography and autofluorescence (AF) imaging were reviewed. Pattern and full-field electroretinography (PERG; ERG) were performed according to international standards and dark-adapted (DA) ERGs were additionally performed after prolonged dark adaptation in most. Leukocyte genomic DNA was extracted and genetic sequencing was carried out by panel-based testing, whole exome or genome sequencing.
Eleven patients (age range 9-87 years, 8 females) were identified to have biallelic RLBP1 mutations. Visual acuity ranged from 6/6 to NPL. All patients under 30 had visual acuity of 6/12 or better and those over 60 had an acuity of 3/36 or worse. The most common findings on fundus examination were peripheral fine white dots (n=6) and/or pigmentary disturbance (n=8). Seven of eight patients showed diffusely reduced AF, and the remaining individual (aged 67 years) had large discrete, scalloped areas of atrophy. Pattern ERG P50 components were undetectable (n=2), subnormal (n=2) or normal (n=1). Full field ERGs were undetectable (n=1; aged 70 years), consistent with rod-cone dystrophy (n=5) or normal (n=1; aged 9 years). Following prolonged dark adaptation, scotopic strong flash (DA10.0) ERGs increased in amplitude in 4 of 5 cases and showed an increase in b-wave peak time in 4, in keeping with a rod system contribution. Three novel RLBP1 mutations were identified, two homozygously (c.701G>A, p.Arg234Gln; c.286-297TTCCTGCGCTTC) and one in a compound heterozygote (c.466C>T, p.Arg*).
The phenotype in patients with biallelic RLBP1 mutations was found to be variable, with white dots, pigmentary abnormalities and diffuse hypoautofluorescence representing the most common features. Full-field ERGs indicate rod-cone dystrophy in most but may be normal in childhood, suggesting a window of opportunity for therapeutic intervention. Partial recovery of abnormal scotopic full field ERGs was observed in some patients following prolonged dark adaptation. Three mutations of RLBP1 novel to the literature were identified.
This is a 2020 ARVO Annual Meeting abstract.
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