Haplotyping Using Long-Range PCR and Nanopore Sequencing to Phase Variants: Lessons Learned From the ABCA4 Locus.

Short-read next-generation sequencing has revolutionized our ability to identify variants underlying inherited diseases; however, it does not allow the phasing of variants to clarify their diagnostic interpretation. The advent of widespread, increasingly accurate long-read sequencing has opened up new applications not currently available through short-read next-generation sequencing. One such use is the ability to phase variants to clarify their diagnostic interpretation and to investigate the increasingly prevalent role of cis-acting variants in the pathogenesis of the inherited disease, so-called complex alleles. Complex alleles are becoming an increasingly prevalent part of the study of genes associated with inherited diseases, for example, in ABCA4-related diseases. We sought to establish a cost-effective method to phase contiguous segments of the 130-kb ABCA4 locus by long-read sequencing of overlapping amplification products. Using the comprehensively characterized CEPH sample, NA12878, we verified the accuracy and robustness of our assay. However, in-field assessment of its utility using clinical test cases was hampered by the paucity and distribution of identified variants and by PCR chimerism, particularly where the number of PCR cycles was high. Despite this, we were able to construct robust phase blocks of up to 94.9 kb, representing 73% of the ABCA4 locus. We conclude that, although haplotype analysis of variants located within discrete amplification products was robust and informative, the stitching together of larger phase blocks using overlapping single-molecule reads remained practically challenging.

Late-Onset Autosomal Dominant Macular Degeneration Caused by Deletion of the CRX Gene.

PURPOSE: To characterize the phenotype observed in a case series with macular disease and determine the cause. DESIGN: Multicenter case series. PARTICIPANTS: Six families (7 patients) with sporadic or multiplex macular disease with onset at 20 to 78 years, and 1 patient with age-related macular degeneration. METHODS: Patients underwent ophthalmic examination; exome, genome, or targeted sequencing; and/or polymerase chain reaction (PCR) amplification of the breakpoint, followed by cloning and Sanger sequencing or direct Sanger sequencing. MAIN OUTCOME MEASURES: Clinical phenotypes, genomic findings, and a hypothesis explaining the mechanism underlying disease in these patients. RESULTS: All 8 cases carried the same deletion encompassing the genes TPRX1, CRX, and SULT2A1, which was absent from 382 control individuals screened by breakpoint PCR and 13 096 Clinical Genetics patients with a range of other inherited conditions screened by array comparative genomic hybridization. Microsatellite genotypes showed that these 7 families are not closely related, but genotypes immediately adjacent to the deletion breakpoints suggest they may share a distant common ancestor. CONCLUSIONS: Previous studies had found that carriers for a single defective CRX allele that was predicted to produce no functional CRX protein had a normal ocular phenotype. Here, we show that CRX whole-gene deletion in fact does cause a dominant late-onset macular disease.

UNITED KINGDOM DATABASE STUDY OF INTRAVITREAL DEXAMETHASONE IMPLANT (OZURDEX) FOR MACULAR EDEMA RELATED TO RETINAL VEIN OCCLUSION.

PURPOSE: To study the treatment patterns, visual outcomes and safety profile of intravitreal dexamethasone implant (IDI) used for the treatment of macular edema secondary to retinal vein occlusion. METHODS: Up to 2 years of routinely collected anonymized data within electronic medical record systems were remotely extracted from 16 centers. The outcome measures include visual outcome, number of injections, and safety measures, including the rate of intraocular pressure (IOP) rise, frequency of IOP-lowering medication usage, and cataract surgery rates. RESULTS: The study included 688 eyes (44.4%) with central retinal vein occlusion and 862 eyes (55.6%) with branch retinal vein occlusion; 1,250 eyes (80.6%) were treatment naive and 28% (275/989) had high IOP or were on IOP-lowering medications before IDI use. It was found that 31% (476) of eyes received two injections, and 11.7% (182) and 3.7% (58) of eyes received three and four injections, respectively. The mean baseline Snellen visual acuity improved from 20/125 to 20/40 after the first injection. The probability of cataract surgery was 15% at 24 months. The proportion of eyes with ≥10 mmHg change from baseline was higher in phakic (14.2%) compared with pseudophakic eyes (5.4%, P = 0.004). Three eyes required IOP filtering surgery (0.2%). CONCLUSION: The visual results of IDI in eyes with macular edema secondary to retinal vein occlusion in the real world are comparable to those of clinical trial setting. Increased IOP in eyes with preexisting ocular hypertension or glaucoma can be controlled with additional medical treatment. Intraocular pressure rise with IDI may be more frequent in phakic than in pseudophakic eyes.

Associations with Non-Persistence with Intra-Vitreal Therapy for Neovascular Age-Related Macular Degeneration at 24 Months.

AIMS: The aim of the study was to investigate non-persistence with treatment for neovascular age-related macular degeneration (NvAMD) before day 720 (24 months) after initiation, explore associations with baseline characteristics and variation between sites. METHODS: Anonymised demographic and clinical data were extracted from electronic medical records at treating National Health Service (NHS) Trusts for NvAMD eyes starting intra-vitreal therapy from 2017 to 2018. Time to non-persistence with treatment, defined as no recorded attendance for either monitoring or treatment for a period ≥6 months, was visualised with a Kaplan-Meier survival plot. Associations with treatment non-persistence were investigated using a Cox proportional hazards model. RESULTS: Analysis included 7,970 eyes of 7,112 patients treated at 13 NHS trusts. Censoring deaths and those eyes in which treatment was stopped permanently, the Kaplan-Meier analyses demonstrated survival figures of 77.7% for persistence with treatment to day 360 and 71.8% to day 720. Hazard ratios for non-persistence with treatment were reduced at 10 sites, relative to the reference, with first-treated eye status and with baseline acuity worse than or equal to LogMAR 1.0. Hazard ratios increased with younger age, in the presence of other ocular co-morbidities and with baseline acuity better than or equal to LogMAR 0.5. After an episode of non-persistence, visual acuity decreased by at least 0.1 and 0.3 LogMAR in 39% and 18% of eyes, respectively. CONCLUSIONS: Non-persistence with treatment was common, especially in the first year of treatment, and was often associated with a decrease in visual acuity. Treatment site, baseline visual acuity, and age were the strongest predictors of treatment non-persistence before day 720. Understanding and addressing reasons for non-persistence are important to ensure that effective but expensive treatments are used cost-effectively and to maintain acuity. Variation in non-persistence between sites, even after adjustment for other variables, suggests that local factors in treatment provision may be particularly important.

Novel SIX6 mutations cause recessively inherited congenital cataract, microcornea, and corneal opacification with or without coloboma and microphthalmia.

Purpose: To investigate the molecular basis of recessively inherited congenital cataract, microcornea, and corneal opacification with or without coloboma and microphthalmia in two consanguineous families. Methods: Conventional autozygosity mapping was performed using single nucleotide polymorphism (SNP) microarrays. Whole-exome sequencing was completed on genomic DNA from one affected member of each family. Exome sequence data were also used for homozygosity mapping and copy number variation analysis. PCR and Sanger sequencing were used to confirm the identification of mutations and to screen further patients. Evolutionary conservation of protein sequences was assessed using CLUSTALW, and protein structures were modeled using PyMol. Results: In family MEP68, a novel homozygous nucleotide substitution in SIX6 was found, c.547G>C, that converts the evolutionarily conserved aspartic acid residue at the 183rd amino acid in the protein to a histidine, p.(Asp183His). This residue mapped to the third helix of the DNA-binding homeobox domain in SIX6, which interacts with the major groove of double-stranded DNA. This interaction is likely to be disrupted by the mutation. In family F1332, a novel homozygous 1034 bp deletion that encompasses the first exon of SIX6 was identified, chr14:g.60975890_60976923del. Both mutations segregated with the disease phenotype as expected for a recessive condition and were absent from publicly available variant databases. Conclusions: Our findings expand the mutation spectrum in this form of inherited eye disease and confirm that homozygous human SIX6 mutations cause a developmental spectrum of ocular phenotypes that includes not only the previously described features of microphthalmia, coloboma, and congenital cataract but also corneal abnormalities.

Novel homozygous mutations in the transcription factor NRL cause non-syndromic retinitis pigmentosa.

Purpose: To describe the clinical phenotype and genetic basis of non-syndromic retinitis pigmentosa (RP) in one family and two sporadic cases with biallelic mutations in the transcription factor neural retina leucine zipper (NRL). Methods: Exome sequencing was performed in one affected family member. Microsatellite genotyping was used for haplotype analysis. PCR and Sanger sequencing were used to confirm mutations in and screen other family members where they were available. The SMART tool for domain prediction helped us build the protein schematic diagram. Results: For family MM1 of Pakistani origin, whole-exome sequencing and microsatellite genotyping revealed homozygosity on chromosome 14 and identified a homozygous stop-loss mutation in NRL, NM_006177.5: c.713G>T, p.*238Lext57, which is predicted to add an extra 57 amino acids to the normal protein chain. The variant segregated with disease symptoms in the family. For case RP-3051 of Spanish ancestry, clinical exome sequencing focusing on the morbid genome highlighted a homozygous nonsense mutation in NRL, c.238C>T, p.Gln80*, as the most likely disease candidate. For case RP-1553 of Romanian ethnicity, targeted-exome sequencing of 73 RP/LCA genes identified a homozygous nonsense mutation in NRL, c.544C>T, p.Gln182*. The variants were either rare or absent in the gnomAD database. Conclusions: NRL mutations predominantly cause dominant retinal disease, but there have been five published reports of mutations causing recessive disease. Here, we present three further examples of recessive RP due to NRL mutations. The phenotypes observed are consistent with those in the previous reports, and the observed mutation types and distribution further confirm distinct patterns for variants in NRL causing recessive and dominant diseases.

New variants and in silico analyses in GRK1 associated Oguchi disease.

Biallelic mutations in G-Protein coupled receptor kinase 1 (GRK1) cause Oguchi disease, a rare subtype of congenital stationary night blindness (CSNB). The purpose of this study was to identify disease causing GRK1 variants and use in-depth bioinformatic analyses to evaluate how their impact on protein structure could lead to pathogenicity. Patients' genomic DNA was sequenced by whole genome, whole exome or focused exome sequencing. Disease associated variants, published and novel, were compared to nondisease associated missense variants. The impact of GRK1 missense variants at the protein level were then predicted using a series of computational tools. We identified twelve previously unpublished cases with biallelic disease associated GRK1 variants, including eight novel variants, and reviewed all GRK1 disease associated variants. Further structure-based scoring revealed a hotspot for missense variants in the kinase domain. In addition, to aid future clinical interpretation, we identified the bioinformatics tools best able to differentiate disease associated from nondisease associated variants. We identified GRK1 variants in Oguchi disease patients and investigated how disease-causing variants may impede protein function in-silico.

Sickle Cell Maculopathy: Prevalence, Associations and Impact on Visual Acuity.

AIMS: To investigate the prevalence of sickle cell maculopathy (SCM), and associations with age, sex, genotype, proliferative sickle cell retinopathy (PSR) stage, and the impact on visual acuity. METHODS: Age, sex, and visual acuity were recorded and spectral domain OCT and ultra-wide-field images of the macula and retina were reviewed in a consecutive series of 74 adults with sickle cell disease. RESULTS: The median age was 37 years (range 19-73 years) and 36 cases (48.6%) were male. SCM was present in at least 1 eye of 40 cases (54.1%) or in 67 of all eyes (42.3%). SCM prevalence was 54.8%, 62.5%, and 25% for the HbSS, HbSC, and HbS/BThal or other genotypes, respectively. SCM was observed in 41 (39.4%) of the eyes with PSR stages 0, 1, and 2, and in 21 (51.2%) of the eyes with PSR stages 3, 4, and 5, respectively. Mild visual impairment or worse was present in 3 eyes (4.8%) with SCM but this was secondary to other pathology. CONCLUSION: SCM is a frequent finding in the eyes of adults with sickle cell disease. The prevalence is similar for the HbSS and HbSC genotypes and is not related to the PSR stage. High-contrast distance visual acuity is typically preserved.

DYNC2H1 hypomorphic or retina-predominant variants cause nonsyndromic retinal degeneration.

PURPOSE: Determining the role of DYNC2H1 variants in nonsyndromic inherited retinal disease (IRD). METHODS: Genome and exome sequencing were performed for five unrelated cases of IRD with no identified variant. In vitro assays were developed to validate the variants identified (fibroblast assay, induced pluripotent stem cell [iPSC] derived retinal organoids, and a dynein motility assay). RESULTS: Four novel DYNC2H1 variants (V1, g.103327020_103327021dup; V2, g.103055779A>T; V3, g.103112272C>G; V4, g.103070104A>C) and one previously reported variant (V5, g.103339363T>G) were identified. In proband 1 (V1/V2), V1 was predicted to introduce a premature termination codon (PTC), whereas V2 disrupted the exon 41 splice donor site causing incomplete skipping of exon 41. V1 and V2 impaired dynein-2 motility in vitro and perturbed IFT88 distribution within cilia. V3, homozygous in probands 2-4, is predicted to cause a PTC in a retina-predominant transcript. Analysis of retinal organoids showed that this new transcript expression increased with organoid differentiation. V4, a novel missense variant, was in trans with V5, previously associated with Jeune asphyxiating thoracic dystrophy (JATD). CONCLUSION: The DYNC2H1 variants discussed herein were either hypomorphic or affecting a retina-predominant transcript and caused nonsyndromic IRD. Dynein variants, specifically DYNC2H1 variants are reported as a cause of non syndromic IRD.

Mutation spectrum and clinical investigation of achromatopsia patients with mutations in the GNAT2 gene.

Achromatopsia (ACHM) is a hereditary cone photoreceptor disorder characterized by the inability to discriminate colors, nystagmus, photophobia, and low-visual acuity. Six genes have been associated with this rare autosomal recessively inherited disease, including the GNAT2 gene encoding the catalytic α-subunit of the G-protein transducin which is expressed in the cone photoreceptor outer segment. Out of a cohort of 1,116 independent families diagnosed with a primary clinical diagnosis of ACHM, we identified 23 patients with ACHM from 19 independent families with likely causative mutations in GNAT2, representing 1.7% of our large ACHM cohort. In total 22 different potentially disease-causing variants, of which 12 are novel, were identified. The mutation spectrum also includes a novel copy number variation, a heterozygous duplication of exon 4, of which the breakpoint matches exactly that of the previously reported exon 4 deletion. Two patients carry just a single heterozygous variant. In addition to our previous study on GNAT2-ACHM, we also present detailed clinical data of these patients.

Where are the missing gene defects in inherited retinal disorders? Intronic and synonymous variants contribute at least to 4% of CACNA1F-mediated inherited retinal disorders.

Inherited retinal disorders (IRD) represent clinically and genetically heterogeneous diseases. To date, pathogenic variants have been identified in ~260 genes. Albeit that many genes are implicated in IRD, for 30-50% of the cases, the gene defect is unknown. These cases may be explained by novel gene defects, by overlooked structural variants, by variants in intronic, promoter or more distant regulatory regions, and represent synonymous variants of known genes contributing to the dysfunction of the respective proteins. Patients with one subgroup of IRD, namely incomplete congenital stationary night blindness (icCSNB), show a very specific phenotype. The major cause of this condition is the presence of a hemizygous pathogenic variant in CACNA1F. A comprehensive study applying direct Sanger sequencing of the gene-coding regions, exome and genome sequencing applied to a large cohort of patients with a clinical diagnosis of icCSNB revealed indeed that seven of the 189 CACNA1F-related cases have intronic and synonymous disease-causing variants leading to missplicing as validated by minigene approaches. These findings highlight that gene-locus sequencing may be a very efficient method in detecting disease-causing variants in clinically well-characterized patients with a diagnosis of IRD, like icCSNB.

Correction: Biallelic sequence and structural variants in RAX2 are a novel cause for autosomal recessive inherited retinal disease.

The original version of this Article contained an incorrect version of Fig. 3, which included two variants initially shown in black text in Fig. 3a that the authors removed from the final manuscript. The correct version of Fig. 3 without the two variants now appears in the PDF and HTML versions of the Article.

Biallelic sequence and structural variants in RAX2 are a novel cause for autosomal recessive inherited retinal disease.

PURPOSE: RAX2 encodes a homeobox-containing transcription factor, in which four monoallelic pathogenic variants have been described in autosomal dominant cone-dominated retinal disease. METHODS: Exome sequencing in a European cohort with inherited retinal disease (IRD) (n = 2086) was combined with protein structure modeling of RAX2 missense variants, bioinformatics analysis of deletion breakpoints, haplotyping of RAX2 variant c.335dup, and clinical assessment of biallelic RAX2-positive cases and carrier family members. RESULTS: Biallelic RAX2 sequence and structural variants were found in five unrelated European index cases, displaying nonsyndromic autosomal recessive retinitis pigmentosa (ARRP) with an age of onset ranging from childhood to the mid-40s (average mid-30s). Protein structure modeling points to loss of function of the novel recessive missense variants and to a dominant-negative effect of the reported dominant RAX2 alleles. Structural variants were fine-mapped to disentangle their underlying mechanisms. Haplotyping of c.335dup in two cases suggests a common ancestry. CONCLUSION: This study supports a role for RAX2 as a novel disease gene for recessive IRD, broadening the mutation spectrum from sequence to structural variants and revealing a founder effect. The identification of biallelic RAX2 pathogenic variants in five unrelated families shows that RAX2 loss of function may be a nonnegligible cause of IRD in unsolved ARRP cases.

Loss-of-Function Mutations in the CFH Gene Affecting Alternatively Encoded Factor H-like 1 Protein Cause Dominant Early-Onset Macular Drusen.

PURPOSE: To characterize the molecular mechanism underpinning early-onset macular drusen (EOMD), a phenotypically severe subtype of age-related macular degeneration (AMD), in a subgroup of patients. DESIGN: Multicenter case series, in vitro experimentation, and retrospective analysis of previously reported variants. PARTICIPANTS: Seven families with apparently autosomal dominant EOMD. METHODS: Patients underwent a comprehensive ophthalmic assessment. Affected individuals from families A, B, and E underwent whole exome sequencing. The probands from families C, D, F, and G underwent Sanger sequencing analysis of the complement factor H (CFH) gene. Mutant recombinant factor H like-1 (FHL-1) proteins were expressed in HEK293 cells to assess the impact on FHL-1 expression and function. Previously reported EOMD-causing variants in CFH were reviewed. MAIN OUTCOME MEASURES: Detailed clinical phenotypes, genomic findings, in vitro characterization of mutation effect on protein function, and postulation of the pathomechanism underpinning EOMD. RESULTS: All affected participants demonstrated bilateral drusen. The earliest reported age of onset was 16 years (median, 46 years). Ultra-rare (minor allele frequency [MAF], ≤0.0001) CFH variants were identified as the cause of disease in each family: CFH c.1243del, p.(Ala415ProfsTer39) het; c.350+1G→T het; c.619+1G→A het, c.380G→A, p.(Arg127His) het; c.694C→T p.(Arg232Ter) het (identified in 2 unrelated families in this cohort); and c.1291T→A, p.(Cys431Ser). All mutations affect complement control protein domains 2 through 7, and thus are predicted to impact both FHL-1, the predominant isoform in Bruch's membrane (BrM) of the macula, and factor H (FH). In vitro analysis of recombinant proteins FHL-1R127H, FHL-1A415f/s, and FHL-1C431S demonstrated that they are not secreted, and thus are loss-of-function proteins. Review of 29 previously reported EOMD-causing mutations found that 75.8% (22/29) impact FHL-1 and FH. In total, 86.2% (25/29) of EOMD-associated variants cause haploinsufficiency of FH or FHL-1. CONCLUSIONS: Early-onset macular drusen is an underrecognized, phenotypically severe subtype of AMD. We propose that haploinsufficiency of FHL-1, the main regulator of the complement pathway in BrM, where drusen develop, is an important mechanism underpinning the development of EOMD in a number of cases. Understanding the molecular basis of EOMD will shed light on AMD pathogenesis given their pathologic similarities.

Mutations in the polyglutamylase gene TTLL5, expressed in photoreceptor cells and spermatozoa, are associated with cone-rod degeneration and reduced male fertility.

Hereditary retinal degenerations encompass a group of genetic diseases characterized by extreme clinical variability. Following next-generation sequencing and autozygome-based screening of patients presenting with a peculiar, recessive form of cone-dominated retinopathy, we identified five homozygous variants [p.(Asp594fs), p.(Gln117*), p.(Met712fs), p.(Ile756Phe), and p.(Glu543Lys)] in the polyglutamylase-encoding gene TTLL5, in eight patients from six families. The two male patients carrying truncating TTLL5 variants also displayed a substantial reduction in sperm motility and infertility, whereas those carrying missense changes were fertile. Defects in this polyglutamylase in humans have recently been associated with cone photoreceptor dystrophy, while mouse models carrying truncating mutations in the same gene also display reduced fertility in male animals. We examined the expression levels of TTLL5 in various human tissues and determined that this gene has multiple viable isoforms, being highly expressed in testis and retina. In addition, antibodies against TTLL5 stained the basal body of photoreceptor cells in rat and the centrosome of the spermatozoon flagellum in humans, suggesting a common mechanism of action in these two cell types. Taken together, our data indicate that mutations in TTLL5 delineate a novel, allele-specific syndrome causing defects in two as yet pathogenically unrelated functions, reproduction and vision.

Biallelic mutations in the autophagy regulator DRAM2 cause retinal dystrophy with early macular involvement.

Retinal dystrophies are an overlapping group of genetically heterogeneous conditions resulting from mutations in more than 250 genes. Here we describe five families affected by an adult-onset retinal dystrophy with early macular involvement and associated central visual loss in the third or fourth decade of life. Affected individuals were found to harbor disease-causing variants in DRAM2 (DNA-damage regulated autophagy modulator protein 2). Homozygosity mapping and exome sequencing in a large, consanguineous British family of Pakistani origin revealed a homozygous frameshift variant (c.140delG [p.Gly47Valfs(∗)3]) in nine affected family members. Sanger sequencing of DRAM2 in 322 unrelated probands with retinal dystrophy revealed one European subject with compound heterozygous DRAM2 changes (c.494G>A [p.Trp165(∗)] and c.131G>A [p.Ser44Asn]). Inspection of previously generated exome sequencing data in unsolved retinal dystrophy cases identified a homozygous variant in an individual of Indian origin (c.64_66del [p.Ala22del]). Independently, a gene-based case-control association study was conducted via an exome sequencing dataset of 18 phenotypically similar case subjects and 1,917 control subjects. Using a recessive model and a binomial test for rare, presumed biallelic, variants, we found DRAM2 to be the most statistically enriched gene; one subject was a homozygote (c.362A>T [p.His121Leu]) and another a compound heterozygote (c.79T>C [p.Tyr27His] and c.217_225del [p.Val73_Tyr75del]). DRAM2 encodes a transmembrane lysosomal protein thought to play a role in the initiation of autophagy. Immunohistochemical analysis showed DRAM2 localization to photoreceptor inner segments and to the apical surface of retinal pigment epithelial cells where it might be involved in the process of photoreceptor renewal and recycling to preserve visual function.

Characterizing Disease Burden and Progression of Geographic Atrophy Secondary to Age-Related Macular Degeneration.

PURPOSE: To understand levels of disease burden and progression in a real-world setting among patients from the United Kingdom with bilateral geographic atrophy (GA) secondary to age-related macular degeneration (AMD). DESIGN: Retrospective cohort analysis of a multicenter electronic medical record (EMR) database. PARTICIPANTS: Patients who were aged ≥50 years with bilateral GA and no history of choroidal neovascularization (CNV) and who attended 1 of 10 clinical sites using the EMR. METHODS: A deidentified data set was constructed from the records held at the 10 sites. An algorithm was used to extract cases with a GA diagnosis, of which 1901 had bilateral GA and form the basis of this report. A sample of records randomly selected from each center was used to validate disease definitions. MAIN OUTCOME MEASURES: Progression to blindness (visual acuity [VA] <20 letters or Snellen 3/60 in the better-seeing eye), driving ineligibility (VA ≤70 letters or Snellen 6/12 in the better-seeing eye), progression to CNV, loss of 10 or more letters, and mean change in VA over time. RESULTS: At first record of GA, 7.1% had a VA in the better-seeing eye equal to or lower than the cutoff for blindness registration and 71.1% had a VA that would have rendered them ineligible to drive. Over time, 16% became legally blind (median time to outcome, 6.2 years) and 66.7% became ineligible to drive (median time to outcome, 1.6 years). In the worse-seeing eye, 40.1% lost ≥10 letters in 2.4 years. Among patients with baseline and 24-month VA measurements, mean VA decline was 6.1 letters in the worse-seeing eye (n = 413) and 12.4 letters in the better-seeing eye (n = 414). The rate of progression to CNV in either eye was 7.4% per patient-year. CONCLUSIONS: At initial diagnosis, based on VA in the better-seeing eye, a high proportion of patients with bilateral GA were ineligible to drive and approximately 7% were eligible for UK blindness registration. The subsequent reduction in VA that occurred in the better-seeing eye would render a further two-thirds ineligible to drive. These findings emphasize the severity of the visual disability associated with GA secondary to AMD.

An Induced Pluripotent Stem Cell Patient Specific Model of Complement Factor H (Y402H) Polymorphism Displays Characteristic Features of Age-Related Macular Degeneration and Indicates a Beneficial Role for UV Light Exposure.

Age-related macular degeneration (AMD) is the most common cause of blindness, accounting for 8.7% of all blindness globally. Vision loss is caused ultimately by apoptosis of the retinal pigment epithelium (RPE) and overlying photoreceptors. Treatments are evolving for the wet form of the disease; however, these do not exist for the dry form. Complement factor H polymorphism in exon 9 (Y402H) has shown a strong association with susceptibility to AMD resulting in complement activation, recruitment of phagocytes, RPE damage, and visual decline. We have derived and characterized induced pluripotent stem cell (iPSC) lines from two subjects without AMD and low-risk genotype and two patients with advanced AMD and high-risk genotype and generated RPE cells that show local secretion of several proteins involved in the complement pathway including factor H, factor I, and factor H-like protein 1. The iPSC RPE cells derived from high-risk patients mimic several key features of AMD including increased inflammation and cellular stress, accumulation of lipid droplets, impaired autophagy, and deposition of "drüsen"-like deposits. The low- and high-risk RPE cells respond differently to intermittent exposure to UV light, which leads to an improvement in cellular and functional phenotype only in the high-risk AMD-RPE cells. Taken together, our data indicate that the patient specific iPSC model provides a robust platform for understanding the role of complement activation in AMD, evaluating new therapies based on complement modulation and drug testing. Stem Cells 2017;35:2305-2320.

VISUAL ACUITY IMPROVEMENT WHEN SWITCHING FROM RANIBIZUMAB TO AFLIBERCEPT IS NOT SUSTAINED.

PURPOSE: To assess whether visual benefits exist in switching to aflibercept in patients who have been chronically treated with ranibizumab for neovascular age-related macular degeneration. METHODS: A multicenter, national, electronic medical record database study was performed. Patients undergoing six continuous monthly ranibizumab injections and then switched to continuous aflibercept were matched to those on continuous ranibizumab therapy. Matching was performed in a 2:1 ratio and based on visual acuity 6 months before and at the time of the switch, and the number of previous ranibizumab injections. RESULTS: Patients who were switched to aflibercept demonstrated transiently significant improvement in visual acuity that peaked at an increase of 0.9 Early Treatment Diabetic Retinopathy Study letters 3 months after the switch, whereas control patients continued on ranibizumab treatment showed a steady decline in visual acuity. Visual acuity differences between the groups were significant (P < 0.05) at 2, 3, and 5 months after the switch. Beginning at 4 months after the switch, the switch group showed a visual acuity decline similar to the control group. CONCLUSION: Transient, nonsustained improvement in visual acuity occurs when switching between anti-vascular endothelial growth factor agents, which may have implications in treating patients on chronic maintenance therapy on one anti-vascular endothelial growth factor medication.

Rare retinal complications of bone marrow transplantation (BMT): a case report.

BACKGROUND: Bone marrow transplantation retinopathy is a rare condition affecting the posterior pole. The purpose of this case report is to highlight the possible risk factors and clinical features. CASE PRESENTATION: A 19y old male with relapsed and refractory acute lymphoblastic leukaemia was admitted under haematology with pyrexia of unknown origin. At the time of his admission, he reported bilateral and sequential visual impairment for 2 days. On examination, there was bilateral profound retinopathy across the posterior poles. This was symmetrical and with associated macular oedema. Infective aetiology was excluded and cyclosporine was stopped. Although no definitive treatment was initiated the visual acuity improved whilst macular oedema fluctuated. CONCLUSION: BMT and chemotherapy can cause ocular complications but these are usually confined to the anterior segment. Posterior segment complications in the form of retinopathy is very rare. We report this case to highlight some of the clinical features and course of disease.