Liran Tiosano

Adult-onset foveomacular vitelliform dystrophy: A fresh perspective

Adult-onset foveomacular vitelliform dystrophy (AFVD) was first described by Gass four decades ago. AFVD is characterized by subretinal vitelliform macular lesions and is usually diagnosed after the age of 40. The lesions gradually increase and then decrease in size over the years, leaving an area of atrophic outer retina and retinal pigment epithelium. This process is accompanied by a loss of visual acuity. Vitelliform lesions are hyperautofluorescent and initially have a dome-shaped appearance on optical coherence tomography. The electro-oculogram and full-field electroretinogram are typically normal, indicating localized retinal pathology. Phenocopies are also associated with other ocular disorders, such as vitreomacular traction, age-related macular degeneration, pseudodrusen, and central serous chorioretinopathy. A minority of AFVD patients have a mutation in the PRPH2, BEST1, IMPG1, or IMPG2 genes. A single-nucleotide polymorphism in the HTRA1 gene has also been associated with this phenotype. Accordingly, the phenotype can arise from alterations in the photoreceptors, retinal pigment epithelium, and/or interphotoreceptor matrix depending on the underlying gene defect. Excess photoreceptor outer segment production and/or impaired outer segment uptake due to impaired phagocytosis are likely underlying mechanisms. At present, no cure is available for AFVD. Thus, the current challenges in the field include identifying the underlying cause in the majority of AFVD cases and the development of effective therapeutic approaches.

Bevacizumab treatment for choroidal neovascularization associated with adult-onset foveomacular vitelliform dystrophy

Purpose To evaluate choroidal neovascularization (CNV) associated with adult-onset foveomacular vitelliform dystrophy (AOFVD) and its response to bevacizumab therapy. Methods Demographics, clinical characteristics, response to bevacizumab therapy, and central foveal thickness (CFT) were retrospectively assessed in 11 eyes with CNV associated with AOFVD. Sixty consecutive patients with neovascular age-related macular degeneration (AMD) were compared to the patients with AOFVD for all clinical characteristics and responses evaluated. Results The mean (±SD) initial logMAR visual acuity (0.7 ± 0.8 vs. 1 ± 0.75), age at onset, number of bevacizumab injections (12.4 ± 10.4 vs 9 ± 6.7), and final logMAR visual acuity (0.87 ± 0.7 vs 1 ± 0.85) were similar between AOFVD and AMD. The mean CFT in AOFVD was reduced from 418 ± 144 μm to 330 ± 64 μm following treatment (p = 0.03). At the final examination, visual acuity had improved in 3 eyes, stabilized in 1 eye, and was reduced in 7 of the AOFVD eyes examined. Conclusions Bevacizumab therapy for AOFVD-associated CNV resulted in reduced foveal thickness, but a guarded visual outcome was still found, due to progression of the vitelliform lesions.

Evaluation of the association of single nucleotide polymorphisms in the PRPH2 gene with adult-onset foveomacular vitelliform dystrophy.

ABSTRACT Objective: A minority of patients with adult-onset foveomacular vitelliform dystrophy (AFVD) carry mutations in the PRPH2 gene. This gene is highly polymorphic and it was suggested that single-nucleotide polymorphisms (SNPs) in PRPH2 may also be associated with AFVD. We aimed to evaluate for such an association. Methods: A single center cohort from a tertiary referral center including 52 consecutive patients with a clinical diagnosis of AFVD and 91 unaffected individuals was assessed. Sanger sequencing was performed for the PRPH2, BEST1, and IMPG1/2 genes. Investigation as to the frequency of minor alleles for SNPs in PRPH2 was performed and compared to HapMap and Exome Variant Server (EVS) data. Results: None of the patients carry a mutation in PRPH2, BEST1, or IMPG1/2. Five of 14 known SNPs (rs835, rs361524, rs434102, rs425876, rs390659) in exon 3 of PRPH2 were identified in AFVD patients. A high frequency and percentage of minor alleles of these five SNPs was found in the Israeli AFVD patients and controls compared with European, Chinese, Japanese and African populations identified via HapMap and EVS (p < 0.05). Power calculation suggested that the sample size was sufficient (80%) to rule out an association with an odds ratio above 2.5. Conclusions: These results suggest that genetic variants in PRPH2 do not compose a major genetic risk factor for AFVD. The Israeli population shows a higher percentage of minor allele frequencies in SNPs in the PRPH2 gene, as compared with other populations. This emphasizes the need for appropriate genetic background when performing SNP association testing.

Characterising the phenotype and progression of sporadic adult-onset foveomacular vitelliform dystrophy

Background/aims Adult-onset foveomacular vitelliform dystrophy (AFVD) is a relatively common macular degeneration which might lead to substantial visual loss. Our purpose was to describe the natural course of genetically evaluated patients with sporadic AFVD. Methods A retrospective, consecutive, cohort study included 95 eyes of 51 patients. Mutations in genes previously associated with AFVD (PRPH2, BEST1, IMPG-1 and IMPG-2) were evaluated. Demographics, clinical characteristics, and spectral domain optical coherence tomography features were analysed. Main outcome measures were changes in the best corrected visual acuity (BCVA) and lesion morphology during the follow-up. Results The mean age (±SD) at diagnosis was 73.8±10.7 years. Mean (±SD) follow-up period was 30.4±16.3 months (range 0–44 months; median 25 months). All patients were genotyped negative for the evaluated mutations. Fifty-three of the eyes were followed for at least 36 months. At baseline these eyes had a mean BCVA (±SD) of 0.27±0.35 LogMAR, and at 36-months BCVA decreased to 0.38±0.35 (p=0.02). At baseline, 23 of these 53 eyes (43.4%) had the vitelliform stage, while only 10 eyes (18.9%) remained at this stage at 36 months (p=0.01). Ellipsoid zone alterations progressed during the follow-up (n=53 eyes) and showed correlation with BCVA reduction (Pearsons correlation coefficient=0.7, p=0.03). Conclusions Sporadic AFVD is a slowly progressing macular degeneration of older people. It is associated with visual decline at the rate of approximately one ETDRS line during 3 years. Patients with sporadic AFVD are usually negative for the known mutations previously associated with this phenotype, and present at an age that is higher than described for monogenic AFVD.