Two patients with Knobloch syndrome due to mutation in COL8A1 gene: case report and review of the literature

BACKGROUND

Knobloch syndrome (KNO, OMIM # 267,750) is a rare ciliopathy group sydrome characterized by a collagen synthesis disorder. It represents an uncommon cause of pediatric retinal detachment. This report presents two cases with different COL18A1 gene mutations, complicated by retinal detachment.

CASE PRESENTATION

Both cases exhibited high myopia and various degrees of occipital skull defect. The first case, a female, had bilateral congenital retinal detachment, posterior embryotoxon, and strabismus. The second case, a male, had unilateral congenital retinal detachment and neuromotor developmental delay. The first case, diagnosed in the early months of life, underwent successful retinal reattachment surgery. However, surgery was not performed on the second case, who presented with late-stage unilateral retinal detachment and pre-phthisis.

CONCLUSIONS

The report describes two patients with Knobloch syndrome, one of whom responded favorably to surgery for retinal detachment in both eyes. Successful anatomical results were achieved with early surgical interventions. It is essential to recognize the phenotypic and genetic heterogeneity within KNO.

Ophthalmic manifestations of Czech dysplasia

Czech dysplasia is an autosomal dominant type 2 collagenopathy that is caused by heterozygosity for the recurrent p.(Arg275Cys) COL2A1 variant. Affected individuals usually present with skeletal abnormalities such as metatarsal hypoplasia of the third and fourth toes and early-onset arthropathy, as well as hearing loss. To date, no ophthalmic findings have been reported in patients with Czech dysplasia even though COL2A1 has been implicated in other ocular conditions such as type 1 Stickler syndrome. For the first time, we report the ocular findings in four families with Czech dysplasia, including type 1 vitreous anomaly, hypoplastic vitreous, retinal tears, and significant refractive error. These novel ocular findings expand the phenotype associated with Czech dysplasia and may aid clinicians as an additional diagnostic feature. Patients with congenital abnormalities of vitreous gel architecture have an increased risk of retinal detachment, and as such, patients may benefit from prophylaxis. Considering that many of the patients did not report any ocular symptoms, vitreous phenotyping is of key importance in identifying the need for counseling with regard to prophylaxis.

Comprehensive exploration of hub genes involved in oxidative stress in rhegmatogenous retinal detachment based on bioinformatics analysis

Rhegmatogenous retinal detachment (RRD) is a type of ophthalmologic emergency, if left untreated, the blindness rate approaches 100 %. The RRD patient postoperative recovery of visual function is unsatisfactory, most notably due to photoreceptor death. We conducted to identify the key genes for oxidative stress (OS) in RRD through bioinformatics analysis and clinical validation, thus providing new ideas for the recovery of visual function in RRD patients after surgery. A gene database for RRD was obtained from the Gene Expression Omnibus (GEO) database (GSE28133). Then we screened differentially expressed OS genes (DEOSGs) from the database and assessed the critical pathways in RRD with Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway. Protein-protein interaction (PPI) networks and hub genes among the common DEOSGs were identified. In addition, we collected general information and vitreous fluid from 42 patients with RRD and 22 controls [11 each of epiretinal membrane (EM) and macular hole (MH)], examined the expression levels of proteins encoded by hub genes in vitreous fluid by enzyme-linked immunosorbent assay (ELISA) to further assess the relationship between the ELISA data and the clinical characteristics of patients with RRD. Ten hub genes (CCL2, ICAM1, STAT3, CD4, ITGAM, PTPRC, CCL5, IL18, TLR2, VCAM1) were finally screened out from the dataset. The ELISA results showed that, compared with the control group, patients with RRD: TLR2 and ICAM-1 were significantly elevated, and CCL2 had a tendency to be elevated, but no statistically significant; RRD patients and MH patients compared with EM patients: STAT3 and VCAM-1 were significantly elevated. We found affected eyes of RRD patients compared with healthy eyes: temporal and nasal retinal nerve fiber layer (RNFL) were significantly thickened. By correlation analysis, we found that: STAT3 was negatively correlated with ocular perfusion pressure (OPP); temporal RNFL was not only significantly positively correlated with CCL2, but also negatively correlated with Scotopic b-wave amplitude. These findings help us to further explore the mechanism of RRD development and provide new ideas for finding postoperative visual function recovery.

Early-Onset Myopia and Retinal Detachment without Typical Microcoria or Severe Proteinuria due to a Novel LAMB2 Variant

PURPOSE

To describe the ocular and renal features, as well as outcomes of retinal detachment repair, in patients with a novel, homozygous laminin β-2 (LAMB2) pathogenic variant.

DESIGN

Single-center retrospective chart review of patients with a homozygous variant, c.619T>C p.(Ser207Pro), in the LAMB2 gene.

SUBJECTS

Eleven patients (22 eyes) from 4 families.

METHODS

Demographic data and ocular findings were recorded. Patients were recalled for a detailed renal evaluation.

MAIN OUTCOME MEASURES

Ocular features, renal features, and outcomes of retinal detachment repair.

RESULTS

The mean age at presentation was 6.0 (range, 1-26) years. None of the study eyes had microcoria, and none of the patients had nephrotic-range proteinuria. The mean refraction and axial length were -7.9 diopters (range, -4.0 to -12.0 diopters) and 25.3 (range, 22.7-27.7) mm, respectively. Eleven eyes (50%) had cataract at presentation. Fifteen eyes had a clear view to the fundus and all showed tessellated myopic fundus, avascular peripheral retina evident clinically or on fluorescein angiography, and rudimentary fovea. Optic disc pallor was observed in 10 eyes (66.7%). Straightened retinal vessels, abnormal vascular emanation (situs inversus) from the optic disc, supernumerary vascular branching at the optic disc, and vascular tortuosity were observed in 10 (66.7%), 2 (13.4%), 2 (13.4%), and 2 (13.4%) eyes, respectively. Discrete areas of punched-out chorioretinal atrophy were observed in 4 (26.7%) eyes. Spectral-domain OCT showed retinal and choroidal thinning in 13 eyes (86.7%), retinoschisis temporal to the fovea in 2 eyes (13.4%), and rudimentary fovea in 15 eyes (100%). Among the 22 eyes, 14 eyes (63.6%) developed rhegmatogenous retinal detachment (RRD), mostly during childhood, of which 5 patients had bilateral RRD. Eight eyes were operated on and 6 (75%) achieved retinal reattachment at the last follow-up. The mean preoperative visual acuity was 20/300 and the mean postoperative visual acuity at the last follow-up was 20/400.

CONCLUSIONS

This study describes a distinct phenotype of LAMB2-related disease with a novel, homozygous LAMB2 variant, and further expands the spectrum of ophthalmic and renal features, and the molecular genetic basis, of LAMB2-related disease. Because the typical microcoria and nephrotic-range proteinuria might be absent, the retinal features can guide the diagnosis.

FINANCIAL DISCLOSURE(S)

The authors have no proprietary or commercial interest in any materials discussed in this article.

Exome sequencing-aided precise diagnosis of four families with type I Stickler syndrome

BACKGROUND

Stickler syndrome is a multisystemic disorder characterized by ophthalmological and non-ophthalmological abnormalities, frequently misdiagnosed due to high clinical heterogeneity. Stickler syndrome type I (STL1) is predominantly caused by mutations in the COL2A1 gene.

METHODS

Exome sequencing and co-segregation analysis were utilized to scrutinize 35 families with high myopia, and pathogenic mutations were identified. Mutant COL2A1 was overexpressed in cells for mechanistic study. A retrospective genotype-phenotype correlation analysis was further conducted.

RESULTS

Two novel pathogenic mutations (c.2895+1G>C and c.3505G>A (p.Val1169Ile)) and two reported mutations (c.1597C>T (p.Arg533*) and c.1693C>T (p.Arg565Cys)) in COL2A1 were identified causing STL1. These mutations are all in the G-X-Y triplet, and c.2895+1G>C contributed to aberrant RNA splicing. COL2A1 mutants tended to form large aggregates in the endoplasmic reticulum (ER) and elevated ER stress. Additionally, mutations c.550G>A (p.Ala184Thr) and c.2806G>A (p.Gly936Ser) in COL2A1 were found in high myopia families, but were likely benign, although c.2806G>A (p.Gly936Ser) is on G-X-Y triplet. Moreover, genotype-phenotype correlation analysis revealed that mutations in exon 2 mainly contribute to retinal detachment, whereas mutations in the collagen alpha-1 chain region of COL2A1 tend to cause non-ophthalmologic symptoms.

CONCLUSION

This study broadens the COL2A1 gene mutation spectrum, provides evidence for ER stress caused by pathogenic COL2A1 mutations and highlights the importance of non-ophthalmological examination in clinical diagnosis of high myopia.

Multiocular defect in the Old English Sheepdog: A canine form of Stickler syndrome type II associated with a missense variant in the collagen-type gene COL11A1

Multiocular defect has been described in different canine breeds, including the Old English Sheepdog. Affected dogs typically present with multiple and various ocular abnormalities. We carried out whole genome sequencing on an Old English Sheepdog that had been diagnosed with hereditary cataracts at the age of five and then referred to a board-certified veterinary ophthalmologist due to owner-reported visual deterioration. An ophthalmic assessment revealed that there was bilateral vitreal degeneration, macrophthalmos, and spherophakia in addition to cataracts. Follow-up consultations revealed cataract progression, retinal detachment, uveitis and secondary glaucoma. Whole genome sequence filtered variants private to the case, shared with another Old English Sheepdog genome and predicted to be deleterious were genotyped in an initial cohort of six Old English Sheepdogs (three affected by multiocular defect and three control dogs without evidence of inherited eye disease). Only one of the twenty-two variants segregated correctly with multiocular defect. The variant is a single nucleotide substitution, located in the collagen-type gene COL11A1, c.1775T>C, that causes an amino acid change, p.Phe1592Ser. Genotyping of an additional 14 Old English Sheepdogs affected by multiocular defect revealed a dominant mode of inheritance with four cases heterozygous for the variant. Further genotyping of hereditary cataract-affected Old English Sheepdogs revealed segregation of the variant in eight out of nine dogs. In humans, variants in the COL11A1 gene are associated with Stickler syndrome type II, also dominantly inherited.

Knobloch syndrome - a rare collagenopathy, revealing peripheral avascular retina

INTRODUCTION

Pediatric rhegmatogenous retinal detachments, especially those presenting at birth or soon afterward, have a high likelihood of syndromic associations that can be confirmed by genetic testing.

MATERIALS AND METHODS

A 5-month-old child was found to have high myopia in the right eye (RE) with highly tessellated fundus, opalescent vitreous, and peripheral thinning. Left eye had a shallow retinal detachment for which he underwent belt buckling. The baby had an occipital skin tag. A provisional diagnosis of Stickler syndrome was made.

RESULTS

On 1-month follow-up, left eye retina was attached and 360° laser barrage was done. Fluorescein angiography was done which revealed peripheral avascular retina in both eyes. MRI and genetic testing were suggestive of syndromic association. Genetic testing revealed pathogenic mutation in COL 18A1 suggestive of Knobloch syndrome in the baby, and both parents were found to be carriers of the same mutation. However, brain MRI showed features not pathognomonic of Knobloch syndrome.

CONCLUSION

Although Knobloch syndrome is associated with vitreoretinal degeneration and high risk of retinal detachment, there seems to be no recommendation for prophylaxis in the other eye and therefore we preferred to observe the RE closely. A unique feature noted in our case was the peripheral avascular zone (PAZ). The PAZ could be contributed by multiple factors such as high myopia, or due to endostatin deficiency (which is a derivative of collagen XVIII) or an underlying WNT signalling abnormality.

Transcriptomic Analysis of Retinal Gene in Experimental Retinal Detachment Rats and Exploration of S100A9 and TLR4 in Human Vitreous

PURPOSE

To screen for the differentially expressed genes in experimental retinal detachment rats, and to explore the expression of S100 calcium-binding protein A9 and Toll-like receptor 4 in the vitreous of rhegmatogenous retinal detachment patients.

METHODS

Three rats of experimental retinal detachment and three normal rats were enrolled in the study. Transcriptomics (RNAseq) sequencing technology was used to screen differentially expressed genes in the retinas of the experimental retinal detachment group and the normal group. The selected differentially expressed genes for gene ontology and Kyoto Encyclopedia of Genes and Genomes functional enrichment analysis were performed. In addition, the vitreous of 15 patients with rhegmatogenous retinal detachment and six patients with the control group were collected. The expressions of S100 calcium-binding protein A9 and Toll-like receptor 4 were detected by Elisa, and the differences in expression levels were analyzed statistically.

RESULTS

A total of 198 differentially expressed genes were screened by RNAseq sequencing, including 118 upregulated genes and 80 downregulated genes. Kyoto Encyclopedia of Genes and Genomes analysis confirmed that the most enriched pathway was the mitogen-activated protein kinase signaling pathway. Compared to the normal group, the expressions of suppressor of cytokine signaling-3, Storkhead box-2, S100 calcium-binding protein A9, Spi-1 proto-oncogene, phosphodiesterase 1B, and kinesin-light chain 1 mRNA in the retinas of the experimental retinal detachment rats were up-regulated, and the expressions of Max interacting protein 1 and the voltage-gated sodium 1 were down-regulated. Compared to the control group, the expressions of S100 calcium-binding protein A9 and Toll-like receptor 4 were upregulated by Elisa in the vitreous humor of rhegmatogenous retinal detachment patients with a statistically significant difference (p all <.05).

CONCLUSION

The differentially expressed genes of experimental retinal detachment rats were suppressor of cytokine signaling-3, Storkhead box-2, S100 calcium-binding protein A9, Spi-1 proto-oncogene, phosphodiesterase 1B, kinesin-light chain 1, Max interacting protein 1, voltage-gated sodium 1, etc. The differences of S100 calcium-binding protein A9 and Toll-like receptor 4 expressions between the rhegmatogenous retinal detachment patients and the control group were statistically significant, indicating that they may play a potential role in the inflammatory process of rhegmatogenous retinal detachment.

Molecular Signatures Integral to Natural Reprogramming in the Pigment Epithelium Cells after Retinal Detachment in Pleurodeles waltl

The reprogramming of retinal pigment epithelium (RPE) cells into retinal cells (transdifferentiation) lies in the bases of retinal regeneration in several Urodela. The identification of the key genes involved in this process helps with looking for approaches to the prevention and treatment of RPE-related degenerative diseases of the human retina. The purpose of our study was to examine the transcriptome changes at initial stages of RPE cell reprogramming in adult newt Pleurodeles waltl. RPE was isolated from the eye samples of day 0, 4, and 7 after experimental surgical detachment of the neural retina and was used for a de novo transcriptome assembly through the RNA-Seq method. A total of 1019 transcripts corresponding to the differently expressed genes have been revealed in silico: the 83 increased the expression at an early stage, and 168 increased the expression at a late stage of RPE reprogramming. We have identified up-regulation of classical early response genes, chaperones and co-chaperones, genes involved in the regulation of protein biosynthesis, suppressors of oncogenes, and EMT-related genes. We revealed the growth in the proportion of down-regulated ribosomal and translation-associated genes. Our findings contribute to revealing the molecular mechanism of RPE reprogramming in Urodela.

The genetics and disease mechanisms of rhegmatogenous retinal detachment

Rhegmatogenous retinal detachment (RRD) is a sight threatening condition that warrants immediate surgical intervention. To date, 29 genes have been associated with monogenic disorders involving RRD. In addition, RRD can occur as a multifactorial disease through a combined effect of multiple genetic variants and non-genetic risk factors. In this review, we provide a comprehensive overview of the spectrum of hereditary disorders involving RRD. We discuss genotype-phenotype correlations of these monogenic disorders, and describe genetic variants associated with RRD through multifactorial inheritance. Furthermore, we evaluate our current understanding of the molecular disease mechanisms of RRD-associated genetic variants on collagen proteins, proteoglycan versican, and the TGF-β pathway. Finally, we review the role of genetics in patient management and prevention of RRD. We provide recommendations for genetic testing and prophylaxis of at-risk patients, and hypothesize on novel therapeutic approaches beyond surgical intervention.

The Expression of Parthanatos Markers and miR-7 Mimic Protects Photoreceptors from Parthanatos by Repressing α-Synuclein in Retinal Detachment

Retinal detachment (RD) refers to the separation between the neuroepithelium and the pigment epithelium layer. It is an important disease leading to irreversible vision damage worldwide, in which photoreceptor cell death plays a major role. α-Synuclein (α-syn) is reportedly involved in numerous mechanisms of neurodegenerative diseases, but the association with photoreceptor damage in RD has not been studied. In this study, elevated transcription levels of α-syn and parthanatos proteins were observed in the vitreous of patients with RD. The expression of α-syn- and parthanatos-related proteins was increased in experimental rat RD, and was involved in the mechanism of photoreceptor damage, which was related to the decreased expression of miR-7a-5p (miR-7). Interestingly, subretinal injection of miR-7 mimic in rats with RD inhibited the expression of retinal α-syn and down-regulated the parthanatos pathway, thereby protecting retinal structure and function. In addition, interference with α-syn in 661W cells decreased the expression of parthanatos death pathway in oxygen and glucose deprivation model. In conclusion, this study demonstrates the presence of parthanatos-related proteins in patients with RD and the role of the miR-7/α-syn/parthanatos pathway in photoreceptor damage in RD.

OCULAR FEATURES ASSOCIATED WITH MUTATIONS IN ATOH7 GENE OVERLAP THOSE WITH FAMILIAL EXUDATIVE VITREORETINOPATHY

BACKGROUND/PURPOSE

To report the ocular findings in three patients with a mutation in the ATOH7 gene.

METHODS

The clinical findings were collected from the medical records including those for magnetic resonance imaging. Three patients of two families who had poor vision since infancy were studied. Genetic testing of the ATOH7 gene was performed.

RESULTS

The three patients had varying degrees of intraocular vascular proliferation associated with advanced retinal detachments as falciform retinal folds or total retinal detachments. This state is referred to as congenital retinal nonattachment. One eye of a sibling had fluorescein angiographic findings of excessive branching of the retinal vessels and fluorescent dye leakage that were consistent with those of familial exudative vitreoretinopathy. Bilateral hypoplasia of the optic nerve was found in all three patients by magnetic resonance imaging. Genetic analysis showed a known in-frame deletion of the ATOH7 gene in all three patients.

CONCLUSION

This is the first report of a patient with a mutation in the ATOH7 gene that had typical vascular patterns of familial exudative vitreoretinopathy in the peripheral retina. The ocular features associated with mutations in the ATOH7 gene overlap those with familial exudative vitreoretinopathy at the early and advanced stages.

Phenotypic expansion of KCNJ13-associated snowflake vitreoretinal degeneration

INTRODUCTION

An 18-year old highly myopic woman presented with bilateral retinoschisis associated with a unilateral macular hole in the right eye and vitreomacular traction in the left eye.

METHODS

Genetic studies disclosed a heterozygous pathogenic variant in the KCNJ13 gene was identified (c.484C>T (p.Arg162Trp)), consistent with a diagnosis of snowflake vitreoretinal degeneration (SVD).

RESULTS

While there were no corneal guttata, juvenile cataracts, or perivascular sheathing in this case, salient features of SVD included a fibrillar vitreous structure, crystalline retinopathy, and flattened optic nerves. The patient developed a FTMH in the left eye at 17 months follow up, followed by a rhegmatogenous retinal detachment (RRD) requiring 2 surgical repairs.

CONCLUSION

This case expands on the spectrum of clinical features in SVD, including retinoschisis and FTMH. It also characterizes optical coherence tomography findings in this rare disease entity. We emphasize the importance of using panel-based genetic testing to clinically distinguish and further define atypical vitreoretinopathies.

TMEM132D and VIPR2 Polymorphisms as Genetic Risk Loci for Retinal Detachment: A Genome-Wide Association Study and Polygenic Risk Score Analysis

Purpose

Retinal detachment (RD) is a sight-threatening ocular disease caused by separation of the neurosensory retina from the underlying retinal pigment epithelium layer. Its genetic basis is unclear because of a limited amount of data. In this study, we aimed to identify genetic risk loci associated with RD in participants without diabetes mellitus and to construct a polygenic risk score (PRS) to predict the risk of RD.

Methods

A genome-wide association study was conducted using data from the Taiwan Biobank to identify RD risk loci. A total of 1533 RD cases and 106,270 controls were recruited, all of whom were Han Chinese. Replication studies were performed using data from the UK Biobank and Biobank Japan. To construct the PRS, a traditional clumping and thresholding method was performed and validated by fivefold cross-validation.

Results

Two novel loci with significant associations were identified. These two genes were TMEM132D (lead single nucleotide polymorphism [SNP]: rs264498, adjusted-P = 7.18 × 10-9) and VIPR2 (lead SNP: rs3812305, adjusted-P = 8.38 × 10-9). The developed PRS was effective in discriminating individuals at high risk of RD with a dose-response relationship. The quartile with the highest risk had an odds ratio of 1244.748 compared to the lowest risk group (95% confidence interval, 175.174-8844.892).

Conclusions

TMEM132D and VIPR2 polymorphisms are genetic candidates linked to RD in Han Chinese populations. Our proposed PRS was effective at discriminating high-risk from low-risk individuals.

Polygenic Risk Score and Rare Variant Burden Identified by Targeted Sequencing in a Group of Patients with Pigment Epithelial Detachment in Age-Related Macular Degeneration

A subset of ophthalmic imaging examination results from 334 patients were subjected to reanalysis to identify a specific group of patients with pigment epithelial detachment (PED) in at least one eye. Overall, we found a subgroup of 47 patients manifesting PED and studied their genotypes in comparison to those of patients with age-related macular degeneration without PED and healthy controls. We established a polygenic risk score that allowed the explanation of 16.3% of the variation within the disease. The highest predictive value was achieved for a model consisting of six non-coding variants: rs760306 (BEST1), rs148662546 (BEST1), rs11569560 (C3), rs74600252 (GUCA1B), rs2240688 (PROM1), and rs185507582 (TCF4). The risk of PED occurrence was found to be the highest in the first tercile, showing a 7.89-fold higher risk compared to the third tercile for AMD without PED (95% CI: 2.87; 21.71, p < 0.001) and a 7.22-fold higher risk compared to the healthy controls (95% CI: 2.60; 20.06, p < 0.001). In addition, we focused on rare variants in targeted genes. The rare variants' burden was compared among the groups, but no statistical significance was observed in the number of rare variants, predicted functional effects, or pathogenicity classification.

Characteristics of a Three-Generation Family with Stickler Syndrome Type I Carrying Two Different COL2A1 Mutations

Stickler Syndrome is typically characterized by ophthalmic manifestations including vitreous degeneration and axial lengthening that predispose to retinal detachment. Systemic findings consist of micrognathia, cleft palate, sensorineural hearing loss, and joint abnormalities. COL2A1 mutations are the most common, however, there is a lack of genotype-phenotype correlations. Retrospective, single-center case series of a three-generation family. Clinical features, surgical requirements, systemic manifestations, and genetic evaluations were collected. Eight individuals clinically displayed Stickler Syndrome, seven of whom had genetic confirmation, and two different COL2A1 mutations (c.3641delC and c.3853G>T) were identified. Both mutations affect exon 51, but display distinct phenotypes. The c.3641delC frameshift mutation resulted in high myopia and associated vitreous and retinal findings. Individuals with the c.3853G>T missense mutation exhibited joint abnormalities, but mild ocular manifestations. One individual in the third generation was biallelic heterozygous for both COL2A1 mutations and showed ocular and joint findings in addition to autism and severe developmental delay. These COL2A1 mutations exhibited distinct eye vs. joint manifestations. The molecular basis for these phenotypic differences remains unknown and demonstrates the need for deep phenotyping in patients with Stickler syndrome to correlate COL2A1 gene function and expression with ocular and systemic findings.

Inflammation and Oxidative Stress Gene Variability in Retinal Detachment Patients with and without Proliferative Vitreoretinopathy

This study investigated the association between certain genetic variations and the risk of developing proliferative vitreoretinopathy (PVR) after surgery. The study was conducted on 192 patients with primary rhegmatogenous retinal detachment (RRD) who underwent 3-port pars plana vitrectomy (PPV). The distribution of single nucleotide polymorphisms (SNPs) located in genes involved in inflammation and oxidative stress associated with PVR pathways were analyzed among patients with and without postoperative PVR grade C1 or higher. A total of 7 defined SNPs of 5 genes were selected for genotyping: rs4880 (SOD2); rs1001179 (CAT); rs1050450 (GPX1); rs1143623, rs16944, rs1071676 (IL1B); rs2910164 (MIR146A) using competitive allele-specific polymerase chain reaction. The association of SNPs with PVR risk was evaluated using logistic regression. Furthermore, the possible association of SNPs with postoperative clinical parameters was evaluated using non-parametric tests. The difference between two genotype frequencies between patients with or without PVR grade C1 or higher was found to be statistically significant: SOD2 rs4880 and IL1B rs1071676. Carriers of at least one polymorphic IL1B rs1071676 GG allele appeared to have better postoperative best-corrected visual acuity only in patients without PVR (p = 0.070). Our study suggests that certain genetic variations may play a role in the development of PVR after surgery. These findings may have important implications for identifying patients at higher risk for PVR and developing new treatments.

Progressive degeneration of the retina in Loxl3 mutant mouse model of Stickler syndrome

Stickler syndrome is a multisystem collagenopathy with affected individuals exhibiting a high rate of ocular complications. Lysyl oxidase-like 3 (LOXL3) is a human disease gene candidate with a critical role in catalyzing collagen crosslinking. A homozygous missense variant of LOXL3 was reported in Stickler syndrome with severe myopia. However, the underlying mechanisms of the LOXL3 missense mutation that causes Stickler syndrome are unknown. In this study, a mouse model of Stickler syndrome induced by LOXL3 mutation (c.2027G ​> ​A, p.Cys676Try) was obtained using CRISPR/Cas9 gene editing techniques. The Loxl3 mutant mice exhibited perinatal death, spinal deformity, and cleft palate, and Loxl3 mutation also induced skeletal dysplasia and progressive visual degeneration. Furthermore, we observed the damage of the bruch's membrane (BrM) and an increase in the levels of glial fibrillary acidic protein (GFAP) and Rpe65 in the Loxl3 mutant mice. Thus, we provided the critical in vivo evidence that Loxl3 possibly has a pivotal role in maintaining the eye function.

MicroRNA Expression in Subretinal Fluid in Eyes Affected by Rhegmatogenous Retinal Detachment

Proliferative vitreoretinopathy (PVR) is an abnormal intraocular scarring process that can complicate cases of rhegmatogenous retinal detachment (RRD). Although previous studies have examined the relevance of microRNAs (miRNAs) in ophthalmic diseases, only a few studies have evaluated the expression profiles of microRNAs in subretinal fluid. We hypothesized that the expression profiles of specific miRNAs may change in response to RRD, in the subretinal fluid that is directly in contact with photoreceptors and the retinal pigment epithelium (RPE). We looked for a potential correlation between the expression of specific miRNAs in eyes with RRD and known clinical risk factors of PVR. A total of 24 patients (59 ± 11 years) who underwent scleral buckling procedure were enrolled in this prospective study. Twenty-four undiluted subretinal fluid samples were collected, RNA was isolated and qRT-PCR was performed to analyze the expression of 12 miRNAs. We found the existence of a positive association between the expression of miR-21 (p = 0.017, r = 0.515) and miR-34 (p = 0.030, r = 0.624) and the duration of symptoms related to retinal detachment. Moreover, the expression of miR-146a tended to decrease in patients who developed PVR. Subretinal fluid constitutes an intriguing biological matrix to evaluate the role of miRNAs leading to the development of PVR.

Stickler and Wagner Syndrome in African Americans

BACKGROUND

Stickler (STL) and Wagner (WGN) syndromes are rare inherited vitreoretinopathies associated with retinal detachments (RD). There is a paucity of case reports describing these diseases in African American patients.

METHODS

An IRB-approved, retrospective chart review of African American patients with genetically proven ocular-only STL or WGN was performed, and 6 patients were identified.

RESULTS

Three patients had a COL2A1 mutation, two had a COL11A1 mutation, and one had a VCAN mutation. None had Pierre Robin facies. All were myopes with lattice degeneration and five had RD. Three underwent RD repair with vitrectomy (PPV), scleral buckle (SB), endolaser (EL), and silicone oil (SO). Two received laser retinopexy for localized RD and one received a prophylactic SB with 360° peripheral laser retinopexy.

CONCLUSION

STL and WGN should be considered in myopic African American patients with lattice degeneration, giant retinal tears, abnormal vitreous, or spontaneous RD. Prophylactic laser treatment and aggressive surgical treatment of RD should be considered. [Ophthalmic Surg Lasers Imaging Retina 2023;54:97-101.].

A Novel Transcriptome Approach to the Investigation of the Molecular Pathology of Vitreous and Retinal Detachment

Retinal detachment (RD) is one of the most common, sight-threatening ocular conditions requiring emergency intervention. Posterior vitreous detachment (PVD) occurs in the majority of an aging population whereby the vitreous body separates from the retina. It is well established that PVD is the common precursor to the most common forms of RD; however, it remains unknown why in most individuals PVD will cause no/few complications (physiological PVD) but in a small percentage will cause retinal tears and detachment (pathological PVD). Despite over 100 years of scientific research, the anatomical definitions of PVD and its pathogenesis remain controversial. Recent research has identified a novel cell population (laminocyte), present at significantly higher numbers in pathological PVD when compared to physiological PVD. We review and summarise the seven distinct clinical sub-groups of retinal breaks and focus on the role of the laminocyte in those secondary to PVD and the transcriptomic profile of this unique cell. Provisional whole transcriptome analysis using bulk RNA-Seq shows marked differentially expressed genes when comparing physiological PVD with PVD associated with RD. The limitations of bulk RNA-Seq are considered and the potential to address these using spatial transcriptomics are discussed. Understanding the pathogenesis of PVD-related retinal tears will provide a baseline for the development of novel therapeutic targets and prophylactic treatments.

The Genetic Architecture of Non-Syndromic Rhegmatogenous Retinal Detachment

Rhegmatogenous retinal detachment (RRD) is the most common form of retinal detachment (RD), affecting 1 in 10,000 patients per year. The condition has significant ocular morbidity, with a sizeable proportion of patients obtaining poor visual outcomes. Despite this, the genetics underpinning Idiopathic Retinal Detachment (IRD) remain poorly understood; this is likely due to small sample sizes in relevant studies. The majority of research pertains to the well-characterised Mende lian syndromes, such as Sticklers and Wagners, associated with RRD. Nevertheless, in recent years, there has been an increasing body of literature identifying the common genetic mutations and mechanisms associated with IRD. Several recent Genomic Wide Association Studies (GWAS) studies have identified a number of genetic loci related to the development of IRD. Our review aims to provide an up-to-date summary of the significant genetic mechanisms and associations of Idiopathic RRD.

Hearing Loss in Stickler Syndrome: An Update

Stickler syndrome is a connective tissue disorder characterized by ocular, skeletal, orofacial and auditory manifestations. Its main symptoms are high myopia, retinal detachment, joint hypermobility, early osteoarthritis, cleft palate, midfacial hypoplasia, micrognathia and hearing loss. Large phenotypical variability is apparent and partly explained by the underlying genetic heterogeneity, including collagen genes (COL2A1, COL11A1, COL11A2, COL9A1, COL9A2, COL9A3) and non-collagen genes (BMP4, LRP2, LOXL3). The most frequent type of Stickler syndrome (COL2A1) is characterized by a rather mild high-frequency sensorineural hearing loss in about half of the patients. COL11A1- and COL11A2-related Stickler syndrome results in more frequent hearing loss, being moderate and involving all frequencies. Hearing loss in the rarer types of Stickler syndrome depends on the gene expression in the cochlea, with moderate to severe downsloping hearing loss for Stickler syndrome caused by biallelic type IX collagen gene mutations and none or mild hearing loss for the non-collagen genes. Inherent to the orofacial manifestations, middle ear problems and temporary conductive hearing loss, especially at young age, are also prevalent. Consequently, hearing loss should be actively sought for and adequately treated in Stickler syndrome patients given its high prevalence and the concomitant visual impairment in most patients.

[Ultrasonographic manifestation and genetic analysis of a fetus with Stickler syndrome]

OBJECTIVE

To carry out genetic analysis for a family with a fetus manifesting micrognathia and a previous history for fetal micromandibular deformity.

METHODS

Systematic ultrasound examination was carried out for the fetus, and the prenatal and postnatal phenotype of the first fetus were retrospectively analyzed. The fetus and his parents were subjected to whole exome sequencing (WES) to identify potential pathogenic variants. Candidate variants were verified by Sanger sequencing.

RESULTS

Fetal ultrasound has indicated micrognathia. The first fetus was found to have micrognathia by prenatal ultrasonography and have featured macrosomia and dyspnea due to with tongue retraction, high palatal arch and small mandibular deformity. WES revealed that the fetus has a harbored a c.3G>C (p.Met1?) variant of the COL2A1 gene, which was inherited from the father who had myopia and retinal detachment.

CONCLUSION

Stickler syndrome is mainly characterized prenatally by micrognathia, in addition with a variety of postnatal anomalies. The c.3G>C (p.Met1?) variant probably underlay the Stickler syndrome in this pedigree.

Retinal Detachment Present at Birth in an Infant With a Novel CTNNB1 Mutation

A full-term neonate was diagnosed on birth with a unilateral total retinal detachment. The contralateral eye had extensive fibrovascular proliferation, temporal dragging, and peripheral nonvascularized retina. Genetic testing confirmed a mutation in the CTNNB1 gene, which has been associated with familiar exudative vitreoretinopathy and phenotypic features including intellectual disability and spastic diplegia. This novel mutation and its associated syndrome should be considered as a cause of retinal detachment presenting in the neonatal period. [Ophthalmic Surg Lasers Imaging Retina 2022; 53:403-405.].

Prevention of Blindness in Stickler Syndrome

Stickler syndromes are inherited conditions caused by abnormalities of structural proteins in the eye, inner ear and cartilage. The risk of retinal detachment, particularly due to the development of giant retinal tears, is high. Stickler syndrome is the most common cause of childhood retinal detachment. Although retinal detachment surgery in the general population has a high success rate, outcomes from surgical repair in Stickler syndrome patients are notoriously poor, providing a strong argument for prophylactic intervention. Variable case selection, absence of molecular genetic sub-typing and inconsistent treatment strategies have all contributed to the historic uncertainty regarding the safety and efficacy of prophylactic treatment. This paper reviews the major published clinical studies that have evaluated different methods and strategies for prophylaxis. Based on the current body of literature, there is extremely strong evidence from cohort comparison studies demonstrating the efficacy and safety of prophylactic retinopexy to reduce, but not eliminate, the risk of retinal detachment in Stickler syndrome patients. It is vital that this body of evidence is provided to Stickler syndrome patients, to enable them to make their own fully informed choice about whether to receive prophylaxis for themselves and particularly on behalf of their affected children, to reduce the risk of retinal detachment.

Dominant Stickler Syndrome

The Stickler syndromes are a group of genetic connective tissue disorders associated with an increased risk of rhegmatogenous retinal detachment, deafness, cleft palate, and premature arthritis. This review article focuses on the molecular genetics of the autosomal dominant forms of the disease. Pathogenic variants in COL2A1 causing Stickler syndrome usually result in haploinsufficiency of the protein, whereas pathogenic variants of type XI collagen more usually exert dominant negative effects. The severity of the disease phenotype is thus dependent on the location and nature of the mutation, as well as the normal developmental role of the respective protein.

Pediatric Retinal Detachment in Homozygous Protein C Deficiency: Genetic and Phenotypic Description of a Single Family

Homozygous protein C deficiency is a rare hypercoagulability disorder. This study describes the ocular manifestations and the genetic background in a family with two affected children. This is a retrospective review of ophthalmic examinations, investigations, genetic testing, and blood work-up of two children with homozygous protein C deficiency from a single family. A family with a positive history of consanguineous marriage was found to have two affected children with homozygous protein C deficiency. Abnormal visual behavior was the presenting symptom. Both children had bilateral total tractional retinal detachments at presentation. Skin manifestations included episodes of discoloration and bruising. Laboratory work-up revealed absent protein C activity. Genetic testing confirmed the presence of a homozygous pathogenic mutation in protein C gene (NM_000312.3: c.1297G>A: p.Gly433Ser). Homozygous protein C deficiency should be considered in the differential diagnosis of early-onset tractional retinal detachment in infancy. Although rare, the ophthalmologist may be the first to encounter the condition, and treatment with protein C replacement or anticoagulants may be life-saving. Examination under anesthesia with fluorescein angiography and laser treatment early in life may be warranted to preserve vision. [Ophthalmic Surg Lasers Imaging Retina. 2022;53:293-296.].

A Splicing Mutation in Slc4a5 Results in Retinal Detachment and Retinal Pigment Epithelium Dysfunction

Fluid and solute transporters of the retinal pigment epithelium (RPE) are core components of the outer blood–retinal barrier. Characterizing these transporters and their role in retinal homeostasis may provide insights into ocular function and disease. Here, we describe RPE defects in tvrm77 mice, which exhibit hypopigmented patches in the central retina. Mapping and nucleotide sequencing of tvrm77 mice revealed a disrupted 5’ splice donor sequence in Slc4a5, a sodium bicarbonate cotransporter gene. Slc4a5 expression was reduced 19.7-fold in tvrm77 RPE relative to controls, and alternative splice variants were detected. SLC4A5 was localized to the Golgi apparatus of cultured human RPE cells and in apical and basal membranes. Fundus imaging, optical coherence tomography, microscopy, and electroretinography (ERG) of tvrm77 mice revealed retinal detachment, hypopigmented patches corresponding to neovascular lesions, and retinal folds. Detachment worsened and outer nuclear layer thickness decreased with age. ERG a- and b-wave response amplitudes were initially normal but declined in older mice. The direct current ERG fast oscillation and light peak were reduced in amplitude at all ages, whereas other RPE-associated responses were unaffected. These results link a new Slc4a5 mutation to subretinal fluid accumulation and altered light-evoked RPE electrophysiological responses, suggesting that SLC4A5 functions at the outer blood–retinal barrier.

Myosin 1f-mediated activation of microglia contributes to the photoreceptor degeneration in a mouse model of retinal detachment

Photoreceptor death and neurodegeneration is the leading cause of irreversible vision loss. The inflammatory response of microglia plays an important role in the process of neurodegeneration. In this study, we chose retinal detachment as the model of photoreceptor degeneration. We found Myosin 1f was upregulated after retinal detachment, and it was specifically expressed in microglia. Deficiency of myosin 1f protected against photoreceptor apoptosis by inhibiting microglia activation. The elimination of microglia can abolish the protective effect of myosin 1f deficiency. After stimulation by LPS, microglia with myosin 1f deficiency showed downregulation of the MAPK and AKT pathways. Our results demonstrated that myosin 1f plays a crucial role in microglia-induced neuroinflammation after retinal injury and photoreceptor degeneration by regulating two classic inflammatory pathways and thereby decreasing the expression of inflammatory cytokines. Knockout of myosin 1f reduces the intensity of the immune response and prevents cell death of photoreceptor, suggesting that myosin 1f can be inhibited to prevent a decline in visual acuity after retinal detachment.

The incidence and awareness of Rhegmatogenous retinal detachment in Pakistani population

Retinal detachment (RD) describes the separation of neurosensory retina from the underlying pigment epithelium. There are various methods of treating RD but in many cases, an unusual delay between occurrence of retinal detachment and surgery has been observed. This study was conducted to find the extent of factors involved in delay in surgery. This cross sectional study was carried out at LRBT Eye Hospital, Lahore for 6 months. The non-probability, consecutive sampling technique was used. The demographic information was recorded. The patients were asked for causes of delay in retinal detachment surgery and all factors were measured. Data was analyzed by SPSS version 21. The mean age of patients was 52±9.86 years; the male to female ratio was 1.5:1. About 9.3% patients said that they do not know where to go, 30% patients thought that it was not a severe condition,36.4% patients thought that it would self-heal,17.1% patients didn't go to the doctor due to financial constraints whereas 7.1% patients did not have VR ophthalmologist near their residence. Statistically significant difference was found between the factors and education level of the patients i.e. p-value<0.05. Our study results concluded that people needed to be educated regarding the importance of retinal detachment and surgical procedures and complications associated with it.

Conditional Knock out of High-Mobility Group Box 1 (HMGB1) in Rods Reduces Autophagy Activation after Retinal Detachment

After retinal detachment (RD), the induction of autophagy protects photoreceptors (PR) from apoptotic cell death. The cytoplasmic high-mobility group box 1 (HMGB1) promotes autophagy. We previously demonstrated that the deletion of HMGB1 from rod PRs results in a more rapid death of these cells after RD. In this work, we tested the hypothesis that the lack of HMGB1 accelerates PR death after RD due to the reduced activation of protective autophagy in the retina after RD. The injection of 1% hyaluronic acid into the subretinal space was used to create acute RD in mice with a rhodopsin-Cre-mediated conditional knockout (cKO) of HMGB1 in rods (HMGB1Δrod) and littermate controls. RD sharply increased the number of apoptotic cells in the outer nuclear layer (ONL), and this number was further increased in HMGB1Δrod mouse retinas. The activation of autophagy after RD was reduced in the HMGB1Δrod mouse retinas compared to controls, as evidenced by diminished levels of autophagy regulatory proteins LC3-II, Beclin1, ATG5/12, and phospho-ATG16L1. The cKO of HMGB1 in rods increased the expression of Fas and the Bax/Bcl-2 ratio in detached retinas, promoting apoptotic cell death. In conclusion, endogenous HMGB1 facilitates autophagy activation in PR cells following RD to promote PR cell survival and reduce programmed apoptotic cell death.

Pleiotropy of a Stickler syndrome genotype

PURPOSE

To report a case of pleiotropy in the COL2A1 gene typically associated with Stickler Syndrome Type 1.

OBSERVATIONS

A patient with a confirmed mutation of the COL2A1 gene presented with an isolated retinitis pigmentosa phenotype.

CONCLUSIONS

The mutated COL2A1 gene in Stickler Syndrome Type 1 represents a site of pleiotropy, highlighting a change in phenotype across the same genotype potentially due to tissue alternative splicing.

Cleft palate morphology, genetic etiology, and risk of mortality in infants with Robin sequence

Robin sequence (RS) has many genetic and nongenetic causes, including isolated Robin sequence (iRS), Stickler syndrome (SS), and other syndromes (SyndRS). The purpose of this study was to determine if the presence and type of cleft palate varies between etiologic groups. A secondary endpoint was to determine the relationship of etiologic group, cleft type, and mortality. Retrospective chart review of patients with RS at two high-volume craniofacial centers. 295 patients with RS identified. CP was identified in 97% with iRS, 95% with SS, and 70% of those with SyndRS (p < .0001). U-shaped CP was seen in 86% of iRS, 82% with SS, but only 27% with SyndRS (p < .0001). At one institution, 12 children (6%) with RS died, all from the SyndRS group (p < .0001). All died due to medical comorbidities related to their syndrome. Only 25% of children who died had a U-shaped CP. The most common palatal morphology among those who died was an intact palate. U-shaped CP was most strongly associated with iRS and SS, and with a lower risk of mortality. RS with submucous CP, cleft lip and palate or intact palate was strongly suggestive of an underlying genetic syndrome and higher risk of mortality.

Identification of a variant in NDP associated with X-linked retinal dysplasia in the English cocker spaniel dog

Purpose

Three related male English Cocker Spaniels (ECS) were reported to be congenitally blind. Examination of one of these revealed complete retinal detachment. A presumptive diagnosis of retinal dysplasia (RD) was provided and pedigree analysis was suggestive of an X-linked mode of inheritance. We sought to investigate the genetic basis of RD in this family of ECS.

Methods

Following whole genome sequencing (WGS) of the one remaining male RD-affected ECS, two distinct investigative approaches were employed: a candidate gene approach and a whole genome approach. In the candidate gene approach, COL9A2, COL9A3, NHEJ1, RS1 and NDP genes were investigated based on their known associations with RD and retinal detachment in dogs and humans. In the whole genome approach, affected WGS was compared with 814 unaffected canids to identify candidate variants, which were filtered based on appropriate segregation and predicted pathogenic effects followed by subsequent investigation of gene function. Candidate variants were tested for appropriate segregation in the ECS family and association with disease was assessed using samples from a total of 180 ECS.

Results

The same variant in NDP (c.653_654insC, p.Met114Hisfs*16) that was predicted to result in 15 aberrant amino acids before a premature stop in norrin protein, was identified independently by both approaches and was shown to segregate appropriately within the ECS family. Association of this variant with X-linked RD was significant (P = 0.0056).

Conclusions

For the first time, we report a variant associated with canine X-linked RD. NDP variants are already known to cause X-linked RD, along with other abnormalities, in human Norrie disease. Thus, the dog may serve as a useful large animal model for research.

Post-hoc analysis of single nucleotide polymorphism profile for eyes with vascularized pigment epithelial detachment due to ARMD

INTRODUCTION

This post-hoc case-control study compares single nucleotide polymorphism (SNP) profile of eyes with vascularized pigment epithelial detachment (vPED) due to age-related macular degeneration (ARMD) with: (1) Control-1 eyes (no ARMD and AREDS Severity Scale 0); and (2) Control-2 eyes (drusen or AREDS Severity Scale 2). SNP profile of High Responders (HR) was also compared with Low Responders (LR) to ranibizumab.

METHODS

Blood samples from 40 patients with vPED treated with ranibizumab were sent for SNP-specific genotype analysis for comparison of variant allele frequencies of 23 SNPs associated with ARMD (VAF) to VAF in 184 Control-1 eyes, and VAF in 85 Control-2 eyes. VAF of HR-50 (⩾50% decrease in PED height) and VAF of HR-75 (⩾75% decrease in PED height) were also compared with VAF of LR.

RESULTS

These SNPs were more frequent in vPED than Control-1 eyes: APOE rs4420638 (A/G), HTRA1 rs104904924 (G/T), VEGF rs943080 (T/C), CFH rs1061170 (T/C), CFH rs2274700 (C/T), CFH rs10737680 (A/C), CFH rs10801555 (G/A). These SNPs were more frequent in vPED than Control-2 eyes: APOE rs4420638 (A/G), CFI rs4698775 (G/T), COL15A1/TGFBR1 rs334353 (T/G). FRK rs3812111 (T/A) was more frequent in HR-50 and HR-75 eyes compared with LR.

CONCLUSION

Seven SNPs were more frequent in vPED eyes than non-ARMD eyes, and three SNPs were more frequent in vPED eyes than drusen eyes. Adjusting for multiplicity, only CFH rs2274700 (C/T) was significant for first comparison, and only COL15A1/TGFBR1 rs334353 (T/G) was significant for second comparison. APOE rs4420638 (A/G) was the single SNP more frequently linked to vPED eyes for both comparisons. FRK rs3812111 (T/A) was consistently associated with high responders.

Two AOS genes attributed to familial exudative vitreoretinopathy with microcephaly: Two case reports

RATIONALE

Familial exudative vitreoretinopathy (FEVR) is an inherited disorder, which is mostly reported to be associated with the mutation of genes involved in the Wnt signaling pathway related to β-catenin. To the best of our knowledge, the involvement of Adams-Oliver syndrome (AOS) genes in FEVR patients have not been reported before.

PATIENT CONCERNS

Two patients with FEVR presented with microcephaly. One of them showed slight scarring of the scalp vertex which is a typical manifestation of AOS. The whole exon sequencing confirmed the diagnosis of AOS with 2 AOS-gene mutations at DOCK6 and ARHGAP31. Further clinical examination revealed that their parents with the same mutations showed FEVR-like vascular anomalies.

DIAGNOSIS

Both patients were diagnosed with AOS through whole exon sequencing, and they presented with some FEVR-like retinopathy including retinal detachment.

INTERVENTIONS

Both patients received vitrectomy for tractional retinal detachment with proliferative vitreoretinopathy. During the follow-up, 1 patient received additional laser photocoagulation for tractional retinal detachment.

OUTCOMES

The 2 patients remained stable in the latest follow up after the treatment.

LESSONS

Microcephaly could be associated with some form of retinopathy. We proposed that mutation of DOCK6 and ARHGAP31 genes could be the possible cause of FEVR associated with microcephaly. Our study suggested that these genes may be candidate genes of FEVR.

Involvement of the Retinal Pigment Epithelium in the Development of Retinal Lattice Degeneration

Lattice degeneration involves thinning of the retina that occurs over time. Here we performed an immunohistological study of tissue sections of human peripheral retinal lattice degeneration to investigate if retinal pigment epithelium (RPE) cells are involved in the pathogenesis of this condition. In two cases of retinal detachment with a large tear that underwent vitreous surgery, retinal lattice degeneration tissue specimens were collected during surgery. In the obtained specimens, both whole mounts and horizontal section slices were prepared, and immunostaining was then performed with hematoxylin and antibodies against glial fibrillary acidic protein (GFAP), RPE-specific protein 65 kDa (RPE65), pan-cytokeratin (pan-CK), and CK18. Hematoxylin staining showed no nuclei in the center of the degenerative lesion, thus suggesting the possibility of the occurrence of apoptosis. In the degenerative lesion specimens, GFAP staining was observed in the center, RPE65 staining was observed in the slightly peripheral region, and pan-CK staining was observed in all areas. However, no obvious CK18 staining was observed. In a monkey retina used as the control specimen of a normal healthy retina, no RPE65 or pan-CK staining was observed in the neural retina. Our findings suggest that migration, proliferation, and differentiation of RPE cells might be involved in the repair of retinal lattice degeneration.

Position of macula lutea and presence of proliferative vitreoretinopathy affect vitreous cytokine expression in rhegmatogenous retinal detachment

Our purpose was to evaluate the concentrations of vitreous cytokines in patients with rhegmatogenous retinal detachment (RRD). We hypothesized that patients with macula on RRD have lower levels of cytokines compared to patients with macula off RRD and proliferative vitreoretinopathy (PVR). Vitreous fluids were collected during 23G pars plana vitrectomy from 58 eyes of 58 patients. Indication for vitrectomy included macula off and macula on RRD, PVR, and idiopathic epiretinal membrane (ERM). A multiplex chemiluminescent immunoassay was performed to measure the concentrations of 48 cytokines, chemokines, and growth factors. Levels of HGF, IL-6, IL-8, IL-16, IFN-gamma, MCP-1, and MIF were significantly higher in all groups of retinal detachment compared to ERM. Levels of CTACK, eotaxin, G-CSF, IP-10, MIG, SCF, SCGF-beta, SDF-1alpha were significantly higher in PVR compared to macula on RRD and ERM. Levels of IL-1ra, IL-5, IL-9, M-CSF, MIP-1alpha, and TRIAL were significantly higher in PVR compared to macula on RRD. Our results indicate that the position of macula lutea and the presence of PVR significantly influence vitreous cytokine expression. The detected proteins may serve as biomarkers to estimate the possibility of PVR formation and may help to invent personalized therapeutic strategies to slow down or prevent PVR.

MicroRNAs in the Vitreous Humor of Patients with Retinal Detachment and a Different Grading of Proliferative Vitreoretinopathy: A Pilot Study

Purpose

Although the expression of microRNAs (miRNAs) in retinal pigment epithelial (RPE) cells undergoing epithelial-mesenchymal transition (EMT) is involved in the pathogenesis of proliferative vitreoretinopathy (PVR), its expression in the vitreous of patients with primary retinal detachment (RD) and different PVR grading has not yet been investigated. We assessed the expression of miRNAs in the vitreous humor (VH) of patients diagnosed with RD and different grading of PVR.

Methods

The VH was extracted from the core of the vitreous chamber in patients who had undergone standard vitrectomy for primary RD. RNA was extracted and TaqMan Low-Density Arrays (TLDAs) were used for miRNA profiling that was performed by single TaqMan assays. A gene ontology (GO) analysis was performed on the differentially expressed miRNAs.

Results

A total of 15 eyes with RD, 3 eyes for each grade of PVR (A, B, C, and D) and 3 from unaffected individuals, were enrolled in this prospective comparative study. Twenty miRNAs were altered in the comparison among pathological groups. Interestingly, the expression of miR-143-3p, miR-224-5p, miR-361-5p, miR-452-5p, miR-486-3p, and miR-891a-5p increased with the worsening of PVR grading. We also identified 34 miRNAs showing differential expression in PVR compared to control vitreous samples. GO analysis showed that the deregulated miRNAs participate in processes previously associated with PVR pathogenesis.

Conclusions

The present pilot study suggested that dysregulated vitreal miRNAs may be considered as a biomarker of PVR and associated with the PVR-related complications in patients with RD.

Translational Relevance

The correlation between vitreal miRNAs and the pathological phenotypes are essential to identify the novel miRNA-based mechanisms underlying the PVR disease that would improve the diagnosis and treatment of the condition.

COL2A1 protective variant reduces sporadic rhegmatogenous retinal detachment severity

Rhegmatogenous retinal detachment (RRD) is the most common type of RD, the separation of neurosensory retina from the underlying retinal pigment epithelium. The RRD patients can be benefited from appropriate treatment if detected early, especially for the people predicted at high risk. In this study, we aimed to investigate the genetic association and clinical correlation of collagen type II alpha 1 (COL2A1) variants with sporadic RRD in a southern Chinese population. Totally 156 RRD patients and 254 control subjects were recruited, and 12 COL2A1 tag single nucleotide polymorphisms were genotyped by the TaqMan assay. The RRD patients had poorer visual acuity (P < 0.001) and lower intraocular pressure (IOP; P < 0.001) in their surgical eyes compared to the fellow eyes. The COL2A1 rs1793958 variant was significantly associated with RRD in the genotypic (P = 0.024), allelic (P = 0.011, odds ratio (OR) = 0.669), recessive (P = 0.011, OR = 0.384) and homozygous models (P = 0.007, OR = 0.348). RRD patients carrying the rs1793958 G allele had smaller retinal detachment area (P = 0.041) and smaller IOP differences (P = 0.046) between the surgical and fellow eyes compared to those carrying the wildtype AA genotype. In summary, this study revealed that the COL2A1 rs1793958 variant is associated with reduced risk of sporadic RRD, and patients carrying rs1793958 G allele have lower RRD severity.

Intrafamilial variability of XYLT2-related spondyloocular syndrome

Spondyloocular syndrome is characterized by generalized osteoporosis, multiple fractures and severe ocular findings. The causative XYLT2 mutations have recently been identified with the use of whole exome sequencing. We report on two siblings with spondyloocular syndrome who presented with varying clinical severity. A novel XYLT2 missense mutation was detected in a region evolutionary conserved across the species. This report along with the previous reports demonstrates that variable expressivity may be possible even within the same family. These two siblings with a novel mutation further expand the clinical and mutational spectrum of spondyloocular syndrome.

Clinical, histopathological and genetic characterisation of oculoskeletal dysplasia in the Northern Inuit Dog

Seven Northern Inuit Dogs (NID) were diagnosed by pedigree analysis with an autosomal recessive inherited oculoskeletal dysplasia (OSD). Short-limbed dwarfism, angular limb deformities and a variable combination of macroglobus, cataracts, lens coloboma, microphakia and vitreopathy were present in all seven dogs, while retinal detachment was diagnosed in five dogs. Autosomal recessive OSD caused by COL9A3 and COL9A2 mutations have previously been identified in the Labrador Retriever (dwarfism with retinal dysplasia 1-drd1) and Samoyed dog (dwarfism with retinal dysplasia 2-drd2) respectively; both of those mutations were excluded in all affected NID. Nine candidate genes were screened in whole genome sequence data; only one variant was identified that was homozygous in two affected NID but absent in controls. This variant was a nonsense single nucleotide polymorphism in COL9A3 predicted to result in a premature termination codon and a truncated protein product. This variant was genotyped in a total of 1,232 dogs. All seven affected NID were homozygous for the variant allele (T/T), while 31/116 OSD-unaffected NID were heterozygous for the variant (C/T) and 85/116 were homozygous for the wildtype allele (C/C); indicating a significant association with OSD (p = 1.41x10-11). A subset of 56 NID unrelated at the parent level were analysed to determine an allele frequency of 0.08, estimating carrier and affected rates to be 15% and 0.6% respectively in NID. All 1,109 non-NID were C/C, suggesting the variant is rare or absent in other breeds. Expression of retinal mRNA was similar between an OSD-affected NID and OSD-unaffected non-NID. In conclusion, a nonsense variant in COL9A3 is strongly associated with OSD in NID, and appears to be widespread in this breed.

LOXL3 Function Beyond Amino Oxidase and Role in Pathologies, Including Cancer

Lysyl oxidase like 3 (LOXL3) is a copper-dependent amine oxidase responsible for the crosslinking of collagen and elastin in the extracellular matrix. LOXL3 belongs to a family including other members: LOX, LOXL1, LOXL2, and LOXL4. Autosomal recessive mutations are rare and described in patients with Stickler syndrome, early-onset myopia and non-syndromic cleft palate. Along with an essential function in embryonic development, multiple biological functions have been attributed to LOXL3 in various pathologies related to amino oxidase activity. Additionally, various novel roles have been described for LOXL3, such as the oxidation of fibronectin in myotendinous junction formation, and of deacetylation and deacetylimination activities of STAT3 to control of inflammatory response. In tumors, three distinct roles were described: (1) LOXL3 interacts with SNAIL and contributes to proliferation and metastasis by inducing epithelial-mesenchymal transition in pancreatic ductal adenocarcinoma cells; (2) LOXL3 is localized predominantly in the nucleus associated with invasion and poor gastric cancer prognosis; (3) LOXL3 interacts with proteins involved in DNA stability and mitosis completion, contributing to melanoma progression and sustained proliferation. Here we review the structure, function and activity of LOXL3 in normal and pathological conditions and discuss the potential of LOXL3 as a therapeutic target in various diseases.

P38 inhibition reverses TGFβ1 and TNFα-induced contraction in a model of proliferative vitreoretinopathy

Proliferative vitreoretinopathy (PVR) is a metaplasia in the vitreous of the eye manifested by the transformation of retinal pigment epithelial (RPE) cells and the development of contracting epiretinal membranes (ERM), which lead to retinal detachment and vision loss. While TGFβ1 and TNFα have been associated with PVR, here we show that these cytokines act synergistically to induce an aggressive contraction phenotype on adult human (ah)RPE. Connected RPE detach upon contraction and form motile membranes that recruit more cells. TGFβ1 and TNFα (TNT)-induced contracting membranes uniquely express muscle and extracellular rearrangement genes. Whole transcriptome RNA sequencing of patient-dissected PVR membranes showed activation of the p38-MAPK signaling pathway. Inhibition of p38 during TNT treatment blocks ahRPE transformation and membrane contraction. Furthermore, TNT-induced membrane contractility can be reversed by p38 inhibition after induction. Therefore, targeting the p38-MAPK pathway may have therapeutic benefits for patients with PVR even after the onset of contracting ERMs.

Marshall and stickler syndrome in one family

The authors present the ocular finding in a patient sent to the Department of Paediatric Ophthalmology at the Children's University Hospital - Faculty of Medicine, Comenius University in Bratislava at the age of 3 months, with congenital glaucoma in her right eye and bilateral high myopia. The family anamnesis of the patient shows repeated occurrence of stunted growth, myopia, facial dysmorphia and cataract. The child's mother had high myopia, the mother's brother underwent cataract surgery, the child's grandmother and her sisters and the child's great grandmother had high myopia and glaucoma, and probably underwent cataract surgery at a young age. The child's mother and grandmother underwent a genetic examination, with a conclusion of Marshall syndrome. Within the framework of neonatal screening, poor cortical auditory evoked potential, a defect of the interventricular septum and bifid uvula were diagnosed in the child. With regard to the overall finding in the patient and the genetic family history, we suspected Marshall syndrome. A genetic examination determined Stickler syndrome type 1 with the presence of mutation in the COL2A gene (variant c.2710C >T (p.Arg904Cys,rs121912882)). Due to high intraocular pressure with the impossibility of compensation by medication, bilateral trabuculectomy was performed on the patient. At present the patient has intraocular pressure compensated with adjuvant medicamentous therapy. With regard to high myopia and pronounced degenerative changes on the periphery of the retina in the sense of lattice degeneration, preventive cryopexy of the retinal periphery is planned. A molecular genetic analysis helped diagnose the pathology as Stickler syndrome type 1, which manifested phenotype symptoms of Marshall syndrome or Stickler syndrome type 2. Key words: Marshall syndrome, Stickler syndrome, mid-facial dysmorfism, myopia, glaucoma, cataract.

iTRAQ Quantitative Proteomic Analysis of Vitreous from Patients with Retinal Detachment

Rhegmatogenous retinal detachment (RRD) is a potentially blinding condition characterized by a physical separation between neurosensory retina and retinal pigment epithelium. Quantitative proteomics can help to understand the changes that occur at the cellular level during RRD, providing additional information about the molecular mechanisms underlying its pathogenesis. In the present study, iTRAQ labeling was combined with two-dimensional LC-ESI-MS/MS to find expression changes in the proteome of vitreous from patients with RRD when compared to control samples. A total of 150 proteins were found differentially expressed in the vitreous of patients with RRD, including 96 overexpressed and 54 underexpressed. Several overexpressed proteins, several such as glycolytic enzymes (fructose-bisphosphate aldolase A, gamma-enolase, and phosphoglycerate kinase 1), glucose transporters (GLUT-1), growth factors (metalloproteinase inhibitor 1), and serine protease inhibitors (plasminogen activator inhibitor 1) are regulated by HIF-1, which suggests that HIF-1 signaling pathway can be triggered in response to RRD. Also, the accumulation of photoreceptor proteins, including phosducin, rhodopsin, and s-arrestin, and vimentin in vitreous may indicate that photoreceptor degeneration occurs in RRD. Also, the accumulation of photoreceptor proteins, including phosducin, rhodopsin, and s-arrestin, and vimentin in vitreous may indicate that photoreceptor degeneration occurs in RRD. Nevertheless, the differentially expressed proteins found in this study suggest that different mechanisms are activated after RRD to promote the survival of retinal cells through complex cellular responses.