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Presentation typeOral presentation
Title[ RECORDED ]Longitudinal Phenotypic Study of Late-Onset Retinal Degeneration due to a Founder Variant c.562C>A p.(Pro188Thr) in the C1QTNF5 Gene
PurposeLate-onset retinal degeneration (L-ORD) is a rare AD retinal dystrophy related to C1QTNF5 gene variants.
MethodsTwenty-six patients (21 - 81 years) due to c.562C>A p.(Pro188Thr) with a mean follow-up time of 8 years (range 1-37 years) underwent an extensive ophthalmic work-up.
ResultsBest-corrected visual acuity (BCVA) and visual fields were maintained up to 50 to 55 years (n=8), with a gradual decline but conservation of functional central vision between 55 to 65 years (n=15), followed by a steep decrease in overall visual function beyond 65 years (n=9). Classic anterior segment findings in L-ORD of abnormally long, anteriorly-inserted lens zonules were absent in most patients (n=24/26). In contrast, findings of iris transillumination and sphincter pupillae atrophy with poor dilation were novel. Patients presented with three completely different initial fundus phenotypes: adjoining pavingstone-like atrophic patches (type 1) (n=6/20); tiny yellow-white subretinal dots (type 2) (n=8/20); or larger yellow, thick, round sub-RPE drusenoid deposits (type 3) (n=4/20). Two patients had a mixed phenotype. Although different in presentation phenotype, patients eventually all progressed to a common panretinal atrophy with diffuse intraretinal pigment migration beyond the age of 65. Progression pace, and thus visual prognosis, differed depending on presentation phenotype. Specifically, type 2 appears to have the more benign course.
ConclusionPhenotypic analysis showed 3 distinct presenting phenotypes with a considerable intrafamilial variability both in age of onset of clinical signs, as well as in disease progress, with a fair visual potential (> 20/40) until the seventh decade.
Conflict of interestNo
Authors 1
DepartmentUZ Gent
Authors 2
Last nameCoppieters F
Authors 3
Last nameDe Bruyne M
Authors 4
Last nameVan Royen J
Authors 5
Last nameRoels D
Authors 6
Last nameSix R
Authors 7
Last nameVan Cauwenbergh C
Authors 8
Last nameDe Baere E
Authors 9
Last nameLeroy BP
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