Background/aims To investigate genotype-phenotype associations in patients with KCNV2 retinopathy.Methods Review of clinical notes, best-corrected visual acuity (BCVA), molecular variants,... Show moreBackground/aims To investigate genotype-phenotype associations in patients with KCNV2 retinopathy.Methods Review of clinical notes, best-corrected visual acuity (BCVA), molecular variants, electroretinography (ERG) and retinal imaging. Subjects were grouped according to the combination of KCNV2 variants-two loss-of-function (TLOF), two missense (TM) or one of each (MLOF)-and parameters were compared.Results Ninety-two patients were included. The mean age of onset (mean +/- SD) in TLOF (n=55), TM (n=23) and MLOF (n=14) groups was 3.51 +/- 0.58, 4.07 +/- 2.76 and 5.54 +/- 3.38 years, respectively. The mean LogMAR BCVA ( +/- SD) at baseline in TLOF, TM and MLOF groups was 0.89 +/- 0.25, 0.67 +/- 0.38 and 0.81 +/- 0.35 for right, and 0.88 +/- 0.26, 0.69 +/- 0.33 and 0.78 +/- 0.33 for left eyes, respectively. The difference in BCVA between groups at baseline was significant in right (p=0.03) and left eyes (p=0.035). Mean outer nuclear layer thickness ( +/- SD) at baseline in TLOF, MLOF and TM groups was 37.07 +/- 15.20 mu m, 40.67 +/- 12.53 and 40.38 +/- 18.67, respectively, which was not significantly different (p=0.85). The mean ellipsoid zone width (EZW) loss ( +/- SD) was 2051 mu m ( +/- 1318) for patients in the TLOF, and 1314 mu m ( +/- 965) for MLOF. Only one patient in the TM group had EZW loss at presentation. There was considerable overlap in ERG findings, although the largest DA 10 ERG b-waves were associated with TLOF and the smallest with TM variants.Conclusions Patients with missense alterations had better BCVA and greater structural integrity. This is important for patient prognostication and counselling, as well as stratification for future gene therapy trials. Show less
Georgiou, M.; Fujinami, K.; Vincent, A.; Nasser, F.; Khateb, S.; Vargas, M.E.; ... ; Michaelides, M. 2021
PURPOSE: To describe the detailed retinal phenotype of KCNV2-associated retinopathy.STUDY DESIGN: Multicenter international retrospective case series.METHODS: Review of retinal imaging including... Show morePURPOSE: To describe the detailed retinal phenotype of KCNV2-associated retinopathy.STUDY DESIGN: Multicenter international retrospective case series.METHODS: Review of retinal imaging including fundus autofluorescence (FAF) and optical coherence tomography (OCT), including qualitative and quantitative analyses.RESULTS: Three distinct macular FAF features were identified: (1) centrally increased signal (n = 35, 41.7%), (2) decreased autofluorescence (n = 27, 31.1%), and (3) ring of increased signal (n = 37, 44.0%). Five distinct FAF groups were identified based on combinations of those features, with 23.5% of patients changing the FAF group over a mean (range) follow-up of 5.9 years (1.9-13.1 years). Qualitative assessment was performed by grading OCT into 5 grades: (1) continuous ellipsoid zone (EZ) (20.5%); (2) EZ disruption (26.1%); (3) EZ absence, without optical gap and with preserved retinal pigment epithelium complex (21.6%); (4) loss of EZ and a hyporeflective zone at the foveola (6.8%); and (5) outer retina and retinal pigment epithelium complex loss (25.0%). Eighty-six patients had scans available from both eyes, with 83 (96.5%) having the same grade in both eyes, and 36.1% changed OCT grade over a mean follow-up of 5.5 years. The annual rate of outer nuclear layer thickness change was similar for right and left eyes.CONCLUSIONS: KCNV2-associated retinopathy is a slowly progressive disease with early retinal changes, which are predominantly symmetric between eyes. The identification of a single OCT or FAF measurement as an endpoint to determine progression that applies to all patients may be challenging, although outer nuclear layer thickness is a potential biomarker. Findings suggest a potential window for intervention until 40 years of age. (C) 2021 The Authors. Published by Elsevier Inc. Show less