Typical best vitelliform dystrophy secondary to biallelic variants in BEST1.

BACKGROUND: Pathogenic variants in BEST1 can cause autosomal dominant or autosomal recessive dystrophy, typically associated with distinct retinal phenotypes. In heterozygous cases, the disorder is commonly characterized by yellow sub-macular lesions in the early stages, known as Best vitelliform macular dystrophy (BVMD). Biallelic variants usually cause a more severe phenotype including diffuse retinal pigment epithelial irregularity and widespread generalized progressive retinopathy, known as autosomal recessive bestrophinopathy (ARB). This study describes three cases with clinical changes consistent with BVMD, however, unusually associated with autosomal recessive inheritance. MATERIALS AND METHODS: Detailed ophthalmic workup included comprehensive ophthalmologic examination, multimodal retinal imaging, full-field and pattern electroretinography (ERG; PERG), and electrooculogram (EOG). Genetic analysis of probands and segregation testing and fundus examination of proband relatives was performed where possible. RESULTS: Three unrelated cases presented with a clinical phenotype typical for BVMD and were found to have biallelic disease-causing variants in BEST1. PERG P50 and ERG were normal in all cases. The EOG was subnormal (probands 1 and 3) or normal/borderline (proband 2). Probands 1 and 2 were homozygous for the BEST1 missense variant c.139C>T, p.Arg47Cys, while proband 3 was homozygous for a deletion, c.536_538delACA, p.Asn179del. The parents of proband 1 were phenotypically normal. Parents of proband 1 and 2 were heterozygous for the same missense variant. CONCLUSIONS: Individuals with biallelic variants in BEST1 can present with a phenotype indistinguishable from BVMD. The same clinical phenotype may not be evident in those harboring the same variants in the heterozygous state. This has implications for genetic counselling and prognosticationA.

The Retinal Phenotype Associated with the p.Pro101Thr BEST1 Variant.

PURPOSE: To describe the retinal phenotype associated with the p.Pro101Thr BEST1 variant. DESIGN: Retrospective, observational case series. PARTICIPANTS: Patients diagnosed with bestrophinopathies in which molecular genetic testing identified the p.Pro101Thr BEST1 as well as healthy carriers among their first-degree relatives. METHODS: Medical records were reviewed to obtain data on family history and ophthalmic examinations, including retinal imaging. The imaging protocol included OCT and fundus autofluorescence using Spectralis HRA + OCT (Heidelberg Engineering). Genetic analysis was performed by next-generation sequencing. MAIN OUTCOME MEASURES: Results of ophthalmic examinations and multimodal imaging features of retinal phenotypes. RESULTS: The c.301C>A, p.Pro101Thr BEST1 missense variant was identified as the causative variant in 8 individuals (all men) from 5 families, accounting for 13% of cases (8/61) and 10% of pathogenic alleles (9/93) in our cohort of patients affected by bestrophinopathies. Seven individuals (14 eyes) had the variant in heterozygous status: all eyes had a hyperopic refractive error (median spherical equivalent of + 3.75 diopters [D]) and 4 individuals had a macular dystrophy with mildly reduced visual acuity (median of 20/25 Snellen), whereas the other 3 were asymptomatic carriers. On multimodal retinal imaging, 5 (36%) out of 14 eyes had subclinical bestrophinopathy, 4 (29%) had typical findings of adult-onset foveomacular vitelliform dystrophy (AOFVD), and the remaining 5 (36%) displayed a pattern dystrophy-like phenotype. Follow-up data were available for 6 subjects, demonstrating clinical stability up to 11 years, in both subclinical and clinical forms. An additional patient with autosomal recessive bestrophinopathy was found to harbor the p.Pro101Thr variant in homozygosity. CONCLUSIONS: The p.Pro101Thr BEST1 variant is likely a frequent cause of bestrophinopathy in the Italian population and can result in autosomal dominant macular dystrophies with incomplete penetrance and mild clinical manifestations as well as autosomal recessive bestrophinopathy. The spectrum of autosomal dominant maculopathy includes the typical AOFVD and a pattern dystrophy-like phenotype. FINANCIAL DISCLOSURE(S): Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Choroidal Neovascularization Is Common in Best Vitelliform Macular Dystrophy and Plays a Role in Vitelliform Lesion Evolution.

OBJECTIVE: Choroidal neovascularization (CNV) is usually considered to be a late-stage complication in Best vitelliform macular dystrophy (BVMD) and can be difficult to diagnose with fluorescein angiography. This study used swept-source (SS) OCT angiography (OCTA) to evaluate the prevalence of CNV in BVMD, identify structural features associated with CNV, and provide insight into the role of CNV in vitelliform lesion evolution. DESIGN: Institutional review board-approved, retrospective, cross-sectional, and longitudinal study. PARTICIPANTS: Patients with molecularly confirmed BVMD. METHODS: Charts from consecutive patients with BVMD imaged with SS-OCTA (PLEX Elite 9000, Carl-Zeiss Meditec Inc) at the University of Iowa from September 2017 to October 2021 were reviewed. Clinical data, including age, gender, best-corrected visual acuity (BCVA), and treatment with intravitreal anti-VEGF injections were recorded. The presence of CNV on SS-OCTA was determined by expert graders and correlated with structural features, such as interstitial fluid, subretinal fluid, nodular subretinal pillar, focal choroidal excavation (FCE), and subfoveal choroidal thickness, with a P value of < 0.05 considered statistically significant. MAIN OUTCOME MEASURES: Presence of CNV on SS-OCTA and correlation with structural features on SS-OCT. RESULTS: A total of 53 eyes from 27 patients (13 women; 48.1%) were included. The mean age was 45 years (range, 8-79 years), and the mean logarithm of the minimum angle of resolution BCVA was 0.38 (range, 0-1). Choroidal neovascularization was identified on SS-OCTA in 27 eyes (50.9%), of which 63.0% had a vitelliform (Gass stage 2) lesion. In 40.7% (11 of 27) of eyes, there was no prior clinical diagnosis of CNV. Other structural features associated with CNV included FCEs (15.1%, 8 of 53 eyes) and nodular pillars (15.1%, 8 of 53 eyes) (P < 0.01). Seven patients had available longitudinal imaging, and most of these patients had CNV visible on SS-OCTA (71.4%; 10 of 14 eyes). CONCLUSION: Choroidal neovascularization is common in BVMD, including in the early stages of the disease. The presence of FCEs or nodular pillars should heighten the clinical suspicion of CNV, which may accelerate vitelliform lesion evolution. FINANCIAL DISCLOSURE(S): Proprietary or commercial disclosure may be found after the references.

BEST1 novel mutation causes Bestrophinopathies in six families with distinct phenotypic diversity.

PURPOSE: To report novel BEST1 variants in six Chinese families with bestrophinopathies of two different inheritance modes and analyze the intrafamilial phenotypic diversity. METHOD: A total of 25 participants including 13 patients and 12 healthy family members from 6 Chinese families with bestrophinopathies were available for genetic and clinical analysis. All of the patients were subjected to comprehensive ophthalmic evaluations and exome sequencing was performed on the probands to detect the causative variants. The pathogenicity of gene variants was predicted using silico analysis and evaluated according to ACMG guidelines. All (likely) pathogenic variants were determined by Sanger sequencing and co-segregation analyses were performed on available family members. The relevant original literature previously reported was retrieved to explore the relationship between BEST1-related gene variants and clinical features. RESULTS: In the 6 families, 3 families (10 patients) were assigned as autosomal dominant bestrophinopathies (VMD) and 3 families (3 patients) were assigned as Autosomal recessive Bestrophinopathies (ARB). A total of 9 variants on the BEST1 gene were identified, containing 7 missense variants, 1 nonsense variant, and 1 frameshift variant, respectively, of which 3 variants c.88A > G (p.Lys30Glu), c.764G > A (p.Arg255Gln) and c.233dupT (p.Ser79Phefs*153) were novel variants. Three families with ARB were detected with heterozygous variants on the BEST1 gene.2 families (8 patients) with BVMD showed markedly irregular dominant inheritance, and the severity of macular lesions varies greatly among individuals of the same family. Among them, the probands showed typical vitelliform lesions in the macula, while the other six patients had no visible signs of the disease by fundus photography (ophthalmoscopy) and minor lesions could be detected on OCT in two patients, the continuity of the ellipsoidal band was interrupted with the chimeric band. The phenotypes of the patients in the three ARB families ranged from typical/atypical vitelliform lesions to extensive extramacular deposits (peripheral spots). CONCLUSION: This study provided evidence that the phenotype of BVMD manifested irregular dominant inheritance, with patients carrying a pathogenic heterozygous variant of BEST1 to develop obvious intrafamilial phenotypic diversity, and the patients who harbor two pathogenic alleles showed recessive inheritance bestrophinopathies with distinct phenotypic diversity. Our study also emphasized the importance of comprehensive genetic analysis in patients with bestrophinopathies, and in such challenging families with distinct intrafamilial phenotypic diversity, it shall provide novel insights into phenotypic assessments of bestrophinopathies, and contribute to better diagnosis, prognosis, and treatment for these patients.

Primary and secondary focal choroidal excavation morphologic phenotypes, associated ocular disorders and prognostic implications.

AIMS: To characterise and classify the morphological, clinical and tomographic characteristics of focal choroidal excavation (FCE) lesions to determine their prognostic implications. METHODS: 36 eyes with FCE (32 patients) underwent multimodal imaging, including spectral domain optical coherence tomography and fundus autofluorescence. FCE lesions were classified into three subtypes: (1) type 1: myopic (central choroidal thickness: <100 µm), (2) type 2: suspected congenital (central choroidal thickness: 100-200 µm, without associated chorioretinal pathology) and (3) type 3: secondary or acquired (central choroidal thickness: >200 µm, with associated chorioretinal pathology). RESULTS: 80.6% of eyes were followed longitudinally (26.8±18.8 months). There were 9 type 1 FCEs (myopic), 8 type 2 FCEs (U-shaped, congenital) and 19 type 3 FCEs (V-shaped, secondary). Type 2 FCEs trended towards larger maximum widths (p=0.0563). Type 3 FCEs were associated with central serous chorioretinopathy or pachyvessels (47.4%), but were also seen in pattern dystrophy, geographic atrophy, inactive choroiditis, torpedo maculopathy and adult-onset vitelliform dystrophy. Choroidal neovascular membranes (CNVMs) were more prevalent in type 3 FCE (41.2% compared with 11.1% for type 1 FCE, p=0.251, and 0% for type 2 FCE, p=0.043). CONCLUSIONS: The FCE types, stratified by central choroidal thickness, demonstrated distinct morphological characteristics and associated findings. The classification scheme held prognostic implications as type 3 FCE with V shapes were associated with other chorioretinal conditions and were more likely to develop CNVM.

Clinical Correlation Between Optical Coherence Tomography Biomarkers and Retinal Sensitivity in Best Vitelliform Macular Dystrophy.

Purpose: To investigate the clinical and imaging features associated with retinal sensitivity in Best vitelliform macular dystrophy (BVMD). Methods: This was a cross-sectional, single-center, observational study. Each patient underwent optical coherence tomography (OCT), near-infrared fundus autofluorescence, and OCT angiography. Macular integrity assessment microperimetry under mesopic conditions was performed to obtain retinal sensitivity thresholds from 68 testing points in the central macula. Structural OCT was used to classify BVMD lesions into four types according to their composition: vitelliform, mixed, subretinal fluid, and atrophy. Multilevel, mixed-effects linear regression was used to determine the factors associated with retinal sensitivity. Results: The study included 57 eyes of 30 patients with BVMD, 48 of which (84%) were in a clinical stage. Mean retinal sensitivity varied according to the composition of the lesion: the vitelliform type registering the highest (22 ± 4.1 dB), followed by mixed (18.73 ± 2.7 dB), subretinal fluid (15.68 ± 4.2 dB), and atrophy types (11.85 ± 4.6 dB). The factors most strongly associated with mean retinal sensitivity in BVMD proved to be the OCT lesion type and outer nuclear layer thickness. Conclusions: Retinal sensitivity in BVMD is influenced by lesion composition and outer nuclear layer thickness. Further studies with long-term follow-up are warranted to examine retinal sensitivity over time and to validate retinal sensitivity changes as biomarkers for BVMD. Translational Relevance: Assessing retinal sensitivity in BVMD provides a new instrument in the clinical characterization of the disease and offers the opportunity to identify imaging biomarkers for use as outcome measures in future clinical trials.

Impaired Bestrophin Channel Activity in an iPSC-RPE Model of Best Vitelliform Macular Dystrophy (BVMD) from an Early Onset Patient Carrying the P77S Dominant Mutation.

Best Vitelliform Macular dystrophy (BVMD) is the most prevalent of the distinctive retinal dystrophies caused by mutations in the BEST1 gene. This gene, which encodes for a homopentameric calcium-activated ion channel, is crucial for the homeostasis and function of the retinal pigment epithelia (RPE), the cell type responsible for recycling the visual pigments generated by photoreceptor cells. In BVMD patients, mutations in this gene induce functional problems in the RPE cell layer with an accumulation of lipofucsin that evolves into cell death and loss of sight. In this work, we employ iPSC-RPE cells derived from a patient with the p.Pro77Ser dominant mutation to determine the correlation between this variant and the ocular phenotype. To this purpose, gene and protein expression and localization are evaluated in iPSC-RPE cells along with functional assays like phagocytosis and anion channel activity. Our cell model shows no differences in gene expression, protein expression/localization, or phagocytosis capacity, but presents an increased chloride entrance, indicating that the p.Pro77Ser variant might be a gain-of-function mutation. We hypothesize that this variant disturbs the neck region of the BEST1 channel, affecting channel function but maintaining cell homeostasis in the short term. This data shed new light on the different phenotypes of dominant mutations in BEST1, and emphasize the importance of understanding its molecular mechanisms. Furthermore, the data widen the knowledge of this pathology and open the door for a better diagnosis and prognosis of the disease.

Best disease presenting as subretinal pigment epithelium hyperreflectivite lesion on spectral-domain optical coherence tomography: Multimodal imaging features.

PURPOSE: To report clinical and multimodal imaging features of Best disease in patients presenting with subretinal pigment epithelium hyperreflective lesions. DESIGN: Retrospective study. METHODS: Clinical examination findings and multimodal imaging features, including color fundus photography, spectral-domain optical coherence tomography (SD-OCT), fundus autofluorescence, fluorescein and indocyanine green angiography (ICGA), and optical coherence tomography angiography (OCTA) images were evaluated retrospectively. RESULTS: We assessed 27 eyes of 16 patients with the diagnosis of Best disease. Only patients presenting with serous macular detachment and subretinal pigment epithelium hyperreflective lesion in one or both eyes were included in this study. In 17 of 27 eyes (63%), fibrosis was identified by multimodal imaging techniques. Although there was no sign of active neovascularization on fundus examination or SD-OCT, a vascular network could be identified in 7 eyes (26%) (in 1 eye with OCTA only and in 6 eyes with both OCTA and ICGA). Active neovascularization was seen in 3 eyes (11%). Treatment was recommended for eyes with active neovascularization, and follow-up was scheduled for eyes with quiescent neovascularization and fibrosis. CONCLUSION: Eyes with Best disease with subretinal pigment epithelium hyperreflective lesion and serous macular detachment may show fibrosis, quiescent neovascularization, or active neovascularization. Multimodal imaging techniques are very important for differentiation of these lesions.

Investigating the role of BEST1 and PRPH2 variants in the molecular aetiology of adult-onset vitelliform macular dystrophies.

Objective: To determine the clinical relevance and frequency of BEST1 and PRPH2 mutations in a clinically diagnosed adult-onset vitelliform macular dystrophy (AVMD) group with Caucasian ethnicity. Methods: The study comprised 24 patients who had been diagnosed with AVMD via indirect fundus ophthalmoscopy and presented with a dome-shaped appearance between the retinal pigment epithelium and photoreceptors on their spectral-domain optical coherence tomography. They had lesion hyper- autofluorescence on their fundus autofluorescence images and were also investigated for BEST1 and PRPH2 mutations for a probable molecular aetiology. Results: No pathogenic or likely pathogenic mutation was detected in the BEST1 and PRPH2 genes of any of the clinically diagnosed AVDM patients. A heterozygous NM_000322.5:c.938C>T (p.Pro313Leu) variant of the PRPH2 gene was detected in 2 non-consanguineous patients. According to current guidelines, this variant was classified as a 'variant of uncertain significance'. Conclusion: In conclusion, AVMD is a genotypic and phenotypic heterogeneous disease. The genetic aetiology could not be explained by sequencing BEST1 and PRPH2 genes in the AVMD patients; however, the variant of PRPH2 could be a cause of predisposition relevant to the phenotype.

Anti-VEGF and Retinal Dystrophies.

The therapeutic approach based on anti-vascular endothelial growth factor (anti-VEGF) molecules can be used to treat two important complications of retinal dystrophies: choroidal neovascularization and macular edema. The macular involvement in retinal dystrophies can lead to further visual deterioration in patients at a young age and already affected by functional limitations. The study reports the effect of anti-VEGF treatment in several subforms of retinal dystrophies, critically discussing advantages and limitations.

"Novel p.Tyr284Cys BEST1 genotype-phenotype correlations of Vitelliform Macular Dystrophy in a family with incomplete penetrance".

Purpose: Vitelliform Macular Dystrophy is an inherited autosomal dominant disease with variable expressivity, caused by a mutation in the BEST1 gene. We report a family with variable expressivity and incomplete penetrance in its members.Materials and Methods: A Mexican family was studied. It was comprised of six individuals (father, mother, and four children). A clinical history was taken, and a complete ophthalmological examination (distance best-corrected visual acuity, slit-lamp biomicroscopy, optical coherence tomography, fundus autofluorescence, optical coherence tomography angiography, and electrophysiological studies) was performed in each individual.Results: Two members presented low visual acuity and vitelliform lesions in different stages in the ocular fundus. The assessment suggested a diagnosis of Vitelliform Macular Dystrophy. Genetic analysis was performed by sequencing of exons 2, 4, 5, 7, 8, and 9 of the BEST1 gene. All patients were carriers of the A variant allele of SNP rs1109748 located in exon 2 (c.219 C > A; p.Ile73=). Also, a missense mutation was identified in exon 7 in the mother and two children (c.851A>G; p.Tyr284Cys). The mother has a normal visual acuity, no abnormal findings in the ophthalmological examination and an abnormal electrooculogram, exhibiting incomplete penetrance.Conclusion: This represents one of the few cases of Vitelliform Macular Dystrophy with incomplete penetrance, being the first in our country and Latin America, and with our reported mutation with this characteristic.

Eight-year multimodal follow-up of recurrent idiopathic acute exudative polymorphous vitelliform maculopathy.

PURPOSE: To describe and analyze clinical findings in a patient with recurrent idiopathic acute exudative polymorphous vitelliform maculopathy (AEPVM), followed in detail, and to propose the diagnostic and follow-up algorithm. DESIGN: Retrospective observational analysis. PATIENT: A young adult male patient diagnosed with idiopathic AEPVM who developed two relapses in a 12-month period eight years after the initial onset. METHODS: Review of clinical charts, multimodal imaging, and electrophysiology findings. The patient repeatedly underwent complete ophthalmic examinations, including best-corrected visual acuity testing (BCVA), slit-lamp and fundus examinations; digital fundus photography, time-domain optical coherence tomography (OCT) in 2009 (Stratus OCT, Carl Zeiss Meditec, USA) and spectral-domain OCT in 2017-2018 (Spectralis-OCT, Heidelberg Engineering, Germany), together with fundus autofluorescence (FAF), fluorescein angiography (FA), and indocyanine green angiography (ICGA), all with HRA2 (Heidelberg Engineering, Germany); microperimetry (MP-1 microperimeter, Nidek, Japan). Laser flare photometry (Kowa FM-600, Japan) and electrophysiology testing were also performed. MAIN OUTCOME MEASURES: Clinical features of long-lasting recurrent idiopathic AEPVM, and diagnostic and follow-up algorithm in such rare cases. RESULTS: Case report of a 25-year-old male Caucasian patient with typical features of AEPVM, including serous neuroepithelial detachment with irregular retinal elevations, ophthalmoscopically resembling retinal folds, with subsequent subretinal accumulation of characteristic yellow-white vitelliform deposits. Features in this case rarely described, or even not yet reported, include indocyanine- and fluorescein-negative intraretinal cystic changes, optic disc hyperfluorescence on FA, serous retinal elevations mimicking retinal folds, increased choroidal thickness, lack of rapid visual recovery, and very slow anatomical improvement of the relapses. Bimonthly fundus autofluorescence evaluation together with SD-OCT were the most informative diagnostic methods, demonstrating the evolution of pathological signs. CONCLUSION: AEPVM may be a recurrent or even chronic condition with uncertain long-term visual outcomes. It may have variable clinical presentations depending on the stage of the disease, and both clinical manifestations and imaging features of different stages of the pathologic process may overlap. Patients should be made aware that visual improvement occurs very slowly, if at all. Bimonthly fundus autofluorescence evaluation together with SD-OCT should be recommended in such cases.

Intraretinal hyperreflective foci in PXE-related retinopathy with acquired vitelliform lesions: a long-term follow-up.

Purposes: To describe the long-term follow-up of a patient affected by Pseudoxanthoma Elasticum (PXE) and acquired macular vitelliform lesions in both eyes. Material and methods: Case report Results: We reported the 9-year follow-up of a patient affected by PXE. We described the onset and the resolution of the vitelliform macular lesions which lasted 5 years. The vitelliform lesion appeared almost simultaneously in both eyes with an initial increase in size, even though asymmetrical. We detected the intraretinal migration of hyper-reflective foci in both eyes during the follow-up. Choroidal neovascularization (CNV) occurred in her right eye during the follow-up. Visual acuity decreased from 20/20 to 20/32 in left eye; from 20/20 to 20/100 in her right eye. Conclusions: we reported the natural history of acquired vitelliform lesion in PXE-related retinopathy describing the Intraretinal hyperreflective foci migration.

Establishment of an induced pluripotent stem cell line (FDEENTi002-A) from a patient with Best's disease carrying c.888C > A mutation in BEST1 gene.

Best's disease (BD) is an inherited retinal degenerative disease caused by mutations in BEST1 gene. A human induced pluripotent stem cell (iPSC) line has been generated with integration-free Sendai virus method from peripheral blood mononuclear cells (PBMCs) of a BD patient carrying c.888C > A mutation in BEST1 gene. This cell line may serve as a model for the study of pathogenesis of BD.

IMAGING OF VITELLIFORM MACULAR LESIONS USING POLARIZATION-SENSITIVE OPTICAL COHERENCE TOMOGRAPHY.

PURPOSE: To examine the involvement of the retinal pigment epithelium (RPE) in the presence of vitelliform macular lesions (VML) in Best vitelliform macular dystrophy (BVMD), autosomal recessive bestrophinopathy, and adult-onset vitelliform macular degeneration using polarization-sensitive optical coherence tomography (PS-OCT). METHODS: A total of 35 eyes of 18 patients were imaged using a PS-OCT system and blue light fundus autofluorescence imaging. Pathogenic mutations in the BEST1 gene, 3 of which were new, were detected in all patients with BVMD and autosomal recessive bestrophinopathy. RESULTS: Polarization-sensitive optical coherence tomography showed a characteristic pattern in all three diseases with nondepolarizing material in the subretinal space consistent with the yellowish VML seen on funduscopy with a visible RPE line below it. A focal RPE thickening was seen in 26 eyes under or at the edge of the VML. Retinal pigment epithelium thickness outside the VML was normal or mildly thinned in patients with BVMD and adult-onset vitelliform macular degeneration but was diffusely thinned or atrophic in patients with autosomal recessive bestrophinopathy. Patients with autosomal recessive bestrophinopathy showed sub-RPE fibrosis alongside the subretinal VML. Polarization-sensitive optical coherence tomography was more reliable in assessing the localization and the integrity of the RPE than spectral domain OCT alone. On spectral domain OCT, identification of the RPE was not possible in 19.4% of eyes. Polarization-sensitive optical coherence tomography allowed for definite identification of the location of VML in respect to the RPE in all eyes, since it provides a tissue-specific contrast. CONCLUSION: Polarization-sensitive optical coherence tomography confirms in vivo the subretinal location of VML and is useful in the assessment of RPE integrity.

NOVEL BEST1 MUTATIONS DETECTED BY NEXT-GENERATION SEQUENCING IN A CHINESE POPULATION WITH VITELLIFORM MACULAR DYSTROPHY.

PURPOSE: To characterize novel BEST1 mutations and the phenotype-genotype correlations in vitelliform macular dystrophy in a Chinese population. METHODS: Seventeen individuals affected by vitelliform macular dystrophy underwent detailed ophthalmic examinations, including a best-corrected visual acuity test, slit-lamp biomicroscopy, fundus photography, spectral-domain optical coherence tomography, fundus autofluorescence, fluorescein angiography, and optical coherence tomography angiography. Next-generation sequencing was used to screen 790 genes frequently involved in common inherited nonsyndromic eye diseases in all participants. Sanger sequencing was used to identify possible disease-causing variants. RESULTS: The mean ± SD age of the patients was 44.20 ± 15.09 (range: 16-69) years. Seven novel BEST1 mutations were identified: six heterozygous missense (p.Thr307Asn, p.Ile295The, p.Leu75Pro, p.Thr2Ser, p.Ser79Tyr, and p.Val81Leu) and one frameshift (p.Glu115GlufsX120) mutation. Choroidal neovascularization was detected in two probands. One individual presented with subfoveal focal choroidal excavation. Arden ratios obtained by electrooculography were less than the 1.5 cutoff value in 7 patients. No mutations were identified in 2 patients, one of whom had a fundus appearance typical of vitelliform macular dystrophy and a decreased Arden ratio (1.2/1.2). CONCLUSION: Patients with the same heterozygous BEST1 mutations exhibited varying phenotypes. Our results have expanded the BEST1 mutation spectrum in a Chinese population with vitelliform macular dystrophy.

Underdeveloped RPE Apical Domain Underlies Lesion Formation in Canine Bestrophinopathies.

Canine bestrophinopathy (cBest) is an important translational model for BEST1-associated maculopathies in man that recapitulates the broad spectrum of clinical and molecular disease aspects observed in patients. Both human and canine bestrophinopathies are characterized by focal to multifocal separations of the retina from the RPE. The lesions can be macular or extramacular, and the specific pathomechanism leading to formation of these lesions remains unclear. We used the naturally occurring canine BEST1 model to examine factors that underlie formation of vitelliform lesions and addressed the susceptibility of the macula to its primary detachment in BEST1-linked maculopathies.

Generation of induced pluripotent stem cells from a patient with Best Dystrophy carrying 11q12.3 (BEST1 (VMD2)) mutation.

Best disease (BD), also termed Best vitelliform macular dystrophy (BVMD), is a juvenile-onset form of macular degeneration and central visual loss. In this report, we generated an induced pluripotent stem cell (iPSC) line, TVGH-iPSC-012-04, from the peripheral blood mononuclear cells of a female patient with BD by using the Sendai virus delivery system. The resulting iPSCs retained the disease-causing DNA mutation, expressed pluripotent markers and could differentiate into three germ layers. We believe that BD patient-specific iPSCs provide a powerful in vitro model for evaluating the pathological phenotypes of the disease.

Optical coherence tomography angiography characterisation of Best disease and associated choroidal neovascularisation.

AIMS: To characterise the vasculature of the retina in patients with Best vitelliform dystrophy, including those with choroidal neovascularisation (CNV), using optical coherence tomography angiography (OCTA) and correlate with fluorescein angiography (FA). METHODS: This prospective observational study included 19 eyes of 10 patients with Best disease. Using OCTA, all layers of retina were qualitatively characterised for each eye. Patients with CNV also underwent FA, and areas of CNV were measured by OCTA and FA and correlated. RESULTS: Retinal characteristics revealed 14 (74%) eyes with abnormal foveal avascular zone (FAZ) in the superficial layer, 19 eyes (100%) had an abnormal FAZ in deep layers, 11 (58%) eyes had a hyper-reflective centre in the superficial layer, 18 (95%) had patchy vascularity loss in the deep layer, 17 (89%) eyes had hyporeflective centre in the choriocapillary (CC) layer and 12 (63%) of those eyes had hyper-reflective material within the hyporeflective centre. Also, notably 6 (86%) CNV eyes had a "halo" or a hypolucent area surrounded in the CNV complex in the outer retinal layer. CNV patterns resembled dense net, loose net, mixed and a new found pattern of a ring shape. CNV measurements revealed an average area of 1.66±1.18mm2 using OCTA and an average area of 0.88±0.76mm2 using FA (p=0.15). CONCLUSION: OCTA reveals that eyes with Best disease have abnormal FAZ, patchy vascularity loss in the superficial and deep layers of the retina and capillary dropout with a hyporeflective centre in CC layer. Further, OCTA is superior to FA in measuring CNV.

MICROPERIMETRY IN BEST VITELLIFORM MACULAR DYSTROPHY.

PURPOSE: To investigate retinal sensitivity in eyes with all the clinical stages of Best vitelliform macular dystrophy (VMD). METHODS: Thirty-two patients affected by VMD in subclinical, vitelliform, pseudohypopyon, vitelliruptive, and atrophic stages were enrolled in this prospective cross-sectional study. Patients underwent a complete ophthalmologic examination, including determination of best-corrected visual acuity (BCVA), staging of the disease (Gass's classification), and microperimetry by means of the macular integrity assessment microperimeter. The primary outcome measure was to describe the alterations in the retinal sensitivity of eyes affected by VMD in different stages. Secondary outcome measures included correlations between retinal sensitivity and best-corrected visual acuity and the correlation between the VMD stage and the specific microperimetry pattern. RESULTS: Mean retinal sensitivity was reduced in all the VMD stages. Nevertheless, vitelliform, pseudohypopyon, and vitelliruptive stages turned out to be very similar, especially within 10°. Fixation was classified as stable in 27 eyes (44.2%), relatively unstable in 16 eyes (26.2%), and unstable in 18 eyes (29.5%). Fixation stability correlated both with the disease stage and best-corrected visual acuity. CONCLUSION: VMD is characterized by complex microperimetric abnormalities, involving the whole macular area. Microperimetry may contribute to the global clinical assessment of patients affected by VMD and could be used in future therapeutic approaches.