Inherited eye diseases in Turkey: Current approaches and future directions.

The aim of this review is to reveal Turkey's current status of medical practice in inherited eye diseases and the necessary steps to improve healthcare services and research activities in this area. Since consanguinity rate is high, disease burden is estimated to be high in Turkey. Universal health insurance system, easily accessible medical specialists, increasing genetic test, and counseling opportunities are the key advantages of Turkey's healthcare system. However, specialized clinics for inherited eye diseases, low-vision rehabilitation services, training of ophthalmologists about the recent developments in ocular genetics, and multidisciplinary translational research are the main headlines needed to be focused for better health services and successful research in Turkey.

Ciliary Tissue Transplantation in the Rabbit Eye: Does the Localization of the Graft Affect Survival?

PURPOSE: To examine whether ciliary body transplantation is applicable, the graft is viable and the localization of the graft material affects graft survival. METHODS: Fifteen female New Zealand white rabbits were used. Three of them were used as donors, and a ciliary body graft was prepared from their enucleated eyes. There are two groups in the study according to the localization of the ciliary body graft in the anterior chamber. The graft was placed on the iris surface close to the pupil margin in group 1 and adjacent to the anterior chamber angle in group 2. Immunosuppressive treatment with cyclosporine A was given to the rabbits of both groups. The rabbits were sacrificed 1 month after ciliary transplantation, and their eyes were enucleated. After fixation, the graft and the surrounding tissue were examined by a pathologist macroscopically and microscopically with hematoxylin and eosin staining. RESULTS: One month after the transplantation, the treated eyes remained inflammation free, and the transplants seemed to be viable with evident vascularization and without hemorrhage and necrotic tissue. When we compared groups 1 and 2, there were no statistically significant differences in the histopathological findings between the groups. The grafts were found to be similar with normal ciliary tissue in regard to necrosis, hemorrhage and fibrosis, and there were no statistically significant differences in inflammatory cell density and in the epithelial cell morphology between the normal ciliary tissue and the grafts. CONCLUSION: Transplantation of allograft ciliary tissue either onto the surface of the iris or the anterior chamber angle under immunosuppression could be an effective treatment for chronic ocular hypotony.

Genetic analysis of CHST6 and TGFBI in Turkish patients with corneal dystrophies: Five novel variations in CHST6.

PURPOSE: To identify pathogenic variations in carbohydrate sulfotransferase 6 (CHST6) and transforming growth factor, beta-induced (TGFBI) genes in Turkish patients with corneal dystrophy (CD). METHODS: In this study, patients with macular corneal dystrophy (MCD; n = 18), granular corneal dystrophy type 1 (GCD1; n = 12), and lattice corneal dystrophy type 1 (LCD1; n = 4), as well as 50 healthy controls, were subjected to clinical and genetic examinations. The level of antigenic keratan sulfate (AgKS) in the serum samples of patients with MCD was determined with enzyme-linked immunosorbent assay (ELISA) to immunophenotypically subtype the patients as MCD type I and MCD type II. DNA was isolated from venous blood samples from the patients and controls. Variations were analyzed with DNA sequencing in the coding region of CHST6 in patients with MCD and exons 4 and 12 in TGFBI in patients with LCD1 and GCD1. Clinical characteristics and the detected variations were evaluated to determine any existing genotype-phenotype correlations. RESULTS: The previously reported R555W mutation in TGFBI was detected in 12 patients with GCD1, and the R124C mutation in TGFBI was detected in four patients with LCD1. Serum AgKS levels indicated that 12 patients with MCD were in subgroup I, and five patients with MCD were in subgroup II. No genetic variation was detected in the coding region of CHST6 for three patients with MCD type II. In other patients with MCD, three previously reported missense variations (c. 1A>T, c.738C>G, and c.631 C>T), three novel missense variations (c.164 T>C, c.526 G>A, c. 610 C>T), and two novel frameshift variations (c.894_895 insG and c. 462_463 delGC) were detected. These variations did not exist in the control chromosomes, 1000 Genomes, and dbSNP. CONCLUSIONS: This is the first molecular analysis of TGFBI and CHST6 in Turkish patients with different types of CD. We detected previously reported, well-known hot spot mutations in TGFBI in the patients with GCD1 and LCD1. Eight likely pathogenic variations in CHST6, five of them novel, were reported in patients with MCD, which enlarges the mutational spectrum of MCD.

CFH Y402H and VEGF Polymorphisms and Anti-VEGF Treatment Response in Exudative Age-Related Macular Degeneration.

PURPOSE: The aim of this study was to evaluate the prevalence of single nucleotide polymorphisms (SNPs) in complement factor H (CFH) Y402H and VEGF rs2146323 and rs699947 in exudative age-related macular degeneration (AMD) and their relationship with intravitreal anti-VEGF treatment response. METHODS: A total of 109 exudative AMD patients and 70 controls were included. Patients were classified as 'good responders' and 'nonresponders' based on the changes in best corrected visual acuity, central foveal thickness, lesion size, and the persistence of retinal hemorrhage after three dosages of anti-VEGF. We examined CFH, VEGF rs2146323 and rs699947 SNPs, and plasma interleukin-6 (IL-6) levels in both groups. RESULTS: In total, 42 patients (38.5%) and 11 controls (15.7%) had homozygote wild genotype TT (p = 0.002). The variant C allele frequency was 45% in controls and 31.7% in patients (p = 0.011). A and C allele frequencies for VEGF rs699947 and rs2416323 were similar between the control and patient groups (p = 0.947, p = 0.378). Both SNPs were similar in responders and nonresponders. No significant difference was detected between plasma IL-6 levels of the control and AMD groups (p = 0.594), but the levels were higher in good responders than nonresponders (p < 0.001). CONCLUSION: CFH Y402H SNP might be protective for AMD in the Turkish population. VEGF rs2146323 and rs699947 SNPs have no relationship to exudative AMD formation, and none of these seem to have any effect on anti-VEGF response.

Current clinical practice and needs assessment in inherited eye diseases from the perspective of ophthalmologists.

BACKGROUND: The clinical approach to inherited eye diseases has evolved due to advances in genetic testing methods and treatment opportunities. However, no data are available on the current practices of ophthalmologists in countries, such as Turkey, with higher rates of consanguinity and inherited eye diseases. The aim of this study was to evaluate the current practices, knowledge, and needs of ophthalmologists in Turkey regarding inherited eye diseases. METHODS: A 29-item self-administered survey with a branching algorithm was developed through Google Forms. The survey link was sent to 2983 ophthalmologists in Turkey. The survey assessed respondents' occupational characteristics, current practices, knowledge about available diagnostic and therapeutic options, and opinions on improving continuing education and healthcare services. RESULTS: Responses from 414 ophthalmologists (20.8%) were analyzed. The responses suggested that ophthalmologists mainly collaborate with medical geneticists in respect of inherited eye diseases. The majority of ophthalmologists reported a lack of knowledge about genetic diagnostic tests, and approximately 90% of the ophthalmologists thought training after residency was inadequate for inherited eye diseases. CONCLUSION: This is the most extensive survey exploring ophthalmologists' practice patterns and needs in a setting without specialists or specialized centers in ophthalmic genetics. The results emphasize the need for continued education on updated approaches to inherited eye diseases.

Mimicking TGFBI Hot-Spot Mutation Did Not Result in Any Deposit Formation in the Zebrafish Cornea.

PURPOSE: Mutations in transforming growth factor beta-induced (TGFBI) protein are associated with a group of corneal dystrophies (CDs), classified as TGFBI-associated CDs, characterized by deposits in the cornea. Mouse models were not proper in several aspects for modelling human disease. The goal of this study was to generate zebrafish mutants to investigate the corneal phenotype and to decide whether zebrafish could be a potential model for TGFBI-associated CDs. METHODS: The conserved arginine residue, codon 117, in zebrafish tgfbi gene was targeted with Clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 method. Cas9 VQR variant was used with two target-specific sgRNAs to generate mutations. The presence of mutations was evaluated by T7 Endonuclease Enzyme (T7EI) assay and the type of the mutations were evaluated by Sanger sequencing. The mutant zebrafish at 3 months and 1 year of age were investigated under the microscope for corneal opacity and eye sections were evaluated histopathologically with hematoxylin-eosin, masson-trichrome and congo red stains for corneal deposits. RESULTS: We achieved indel variation at the target sequence that resulted in p.Ser115_Arg117delinsLeu (c. 347_353delinsT) by nonhomology mediated repair in F1. This zebrafish mutation had the potential to mimic two disease-causing mutations reported in human cases previously: R124L and R124L + del125-126. Mutant zebrafish did not show any corneal opacity or corneal deposits at 3 months and 1 year of age. CONCLUSION: This study generated the first zebrafish model mimicking the R124 hot spot mutation in TGFBI-associated CDs. However, evaluations even at 1 year of age did not reveal any deposits in the cornea histopathologically. This study increased the cautions for modelling TGFBI-associated CDs in zebrafish in addition to differences in the corneal structure between zebrafish and humans.

The Role of FOXP3 Polymorphisms in Graves' Disease with or without Ophthalmopathy in a Turkish Population.

Objectives: Forkhead box P3 (FOXP3) gene polymorphisms have been evaluated in many autoimmune diseases, including Graves' disease (GD), in different populations. However, those polymorphisms have not been analyzed in GD or Graves' ophthalmopathy (GO) in the Turkish population. In this study, we aimed to evaluate the frequency of FOXP3 polymorphisms in GD with or without ophthalmopathy in a Turkish population. Materials and Methods: The study included 100 patients with GO, 74 patients with GD without ophthalmopathy, and 100 age- and sex-matched healthy controls. In all study participants, rs3761547 (-3499 A/G), rs3761548 (-3279 C/A), and rs3761549 (-2383 C/T) single nucleotide polymorphisms (SNPs) were detected using the polymerase chain reaction-restriction fragment length polymorphism method. The chi-square test was used to evaluate genotype and allele frequencies. Odds ratios and 95% confidence intervals were calculated for genotype and allele risks. Results: In the patient group (including GD with or without ophthalmopathy), the rs3761548 AC and AA genotype and rs3761549 CT genotype were significantly more frequent than in the control group (all p<0.05). No genotypic and allelic differences were observed for rs3761547 between the patient and control groups (all p>0.05). There was no statistically significant difference between the GO and GD without ophthalmopathy groups concerning the allele and genotype frequencies of all three FOXP3 SNPs (all p>0.05). Conclusion: The AC and AA genotypes of rs3761548 (-3279) and CT genotype of rs3761549 (-2383 C/T) were shown to be possible risk factors for GD development in the Turkish population. However, none of the three SNPs was shown to be associated with the development of GO in patients with GD.

Evaluation of Central and Peripheral Retinal Vascular Changes in the Fellow Eyes of Patients with Unilateral Retinal Vein Occlusions

Objectives: To evaluate the subtle peripheral retinal and macular vascular changes in the fellow eyes of patients with unilateral retinal vein occlusion (RVO). Materials and Methods: This retrospective study included 53 patients with unilateral RVO and 44 age-matched controls. The frequency of peripheral retinal vascular pathologies in both eyes was evaluated using high quality ultra-wide field fluorescein angiography (UWFFA). Macular vascular density, flow area, and foveal avascular zone measurements from optical coherence tomography angiography (OCTA) were analyzed together with laser flare photometry values in patients and controls. Results: Peripheral retinal vascular pathologies were detected on UWFFA in the fellow eyes of 36 (67.9%) patients. No significant central vascular pathologies were detected on OCTA and there was no significant difference in OCTA parameters between the fellow eyes and the controls. Flare values did not differ significantly between the control and the fellow eyes. Conclusion: Two thirds of the fellow eyes of unilateral RVO patients had subtle peripheral retinal vascular changes, while there was no significant microvascular change detected with OCTA in the macula. This suggests that vascular changes caused by systemic vascular disorders probably first start in the peripheral retina of the fellow eyes of patients with RVO.