Beyond the phenotype: Exploring inherited retinal diseases with targeted next-generation sequencing in a Turkish cohort.

This research aims to compile recent clinical and genetic data from Turkish patients with inherited retinal disorders and evaluate the effectiveness of targeted Next-generation sequencing panels. The study included Turkish individuals with hereditary retinal diseases who visited the Medical Genetic Department of Erciyes University between 2019 and 2022. One proband per family was selected based on eligibility. We used Hereditary Disorder Solution (HDS) by Sophia Genetics and performed next-generation sequencing (NGS) with Illumina NextSeq-500. Bioinformatics analysis using Sophia DDM® SaaS algorithms and ACMG guidelines classified genomic changes. The study involved 354 probands. Disease-causing variants were found in 58.1% of patients, with ABCA4, USH2A, RDH12, and EYS being the most frequently implicated genes. Forty-eight novel variants were detected. This study enhances the knowledge of clinical diagnoses, symptom onset, inheritance patterns, and genetic details for Turkish individuals with hereditary retinal disease. It contributes to broader health strategies by enabling comparisons with other studies.

Evaluation of Full-Field Stimulus Threshold Test Results in Retinitis Pigmentosa: Relationship with Full-Field Electroretinography, Multifocal Electroretinography, Optical Coherence Tomography, and Visual Field.

Objectives: The full-field stimulus threshold (FST) test was developed to evaluate the efficacy and safety of treatments of hereditary retinal diseases. In this study we performed the FST test in patients with retinitis pigmentosa (RP) and compared the results with findings from other ophthalmological tests. Materials and Methods: The study included 51 intermediate and advanced RP patients and 21 normal subjects. All patients and controls underwent routine examination and ophthalmological tests including visual field, optical coherence tomography, full-field and multifocal electroretinography (mfERG), and FST tests. During FST testing, the perception thresholds of retina to the white, blue, and red FST were determined in decibels. Results: The mean age of the patients and the controls were 35.2 and 33.5 years, respectively. For all RP patients, no response was obtained on full-field ERG. All subjects were able to perform reliable FST tests. The mean values of visual acuity and central macular thickness were significantly lower and visual field mean deviation values were significantly higher in the RP group than the controls. When we evaluated the mfERG findings, the mean P1 wave amplitudes in all rings were significantly lower and the mean peak times were significantly longer in RP patients than controls. In comparisons of FST test results, the mean values for white, blue, red and the difference between blue-red thresholds were significantly lower in the RP group than the control group. Conclusion: The FST test is a fast and a reliable exam which can be done in subjects with poor visual acuity and reduced visual field. The results of this study confirm that the FST test can measure retinal sensitivity in severely affected RP subjects with flat flash ERG.

ABCA4 variant screening in a Turkish cohort with Stargardt disease.

PURPOSE: This study aims to evaluate the ABCA4 variants in patients diagnosed with Stargardt disease. METHODS: This is a retrospective study designed to investigate variants in the ABCA4 in Stargardt disease and the clinical findings of the cases. Sex, age, age of onset of symptoms, best-corrected visual acuity, color fundus photography, optical coherence tomography, and visual field test of the patients were recorded. Genetic analyses were screened, and patients with at least two variants in the ABCA4 were included in this study. RESULTS: Twenty-seven patients diagnosed with Stargardt disease with the ABCA4 variants were included in this study. Twelve of them (44.4%) were female and fifteen (55.5%) were male. The mean age of the cases was 27.44 years (ranging from 8 to 56 years). Thirty different variants were detected in 54 ABCA4 alleles of 27 patients. The two most common pathogenic variants were c.5882 G>A p.(Gly1961Glu) and c.52C>T p.(Arg18Trp) in this cohort. Two novel variants were identified (c.3855_3856dup, c.1554 + 3_1554 + 4del) and the patient with the c.1554 + 3_1554 + 4del variant additionally had a different ABCA4 variant in trans. The other novel variant was homozygous. CONCLUSIONS: In this study, two novel variants were described in a Turkish cohort with Stargardt disease. The variant c.52C>T p.(Arg18Trp) was the most common disease-causing variant besides the c.5882 G>A p.(Gly1961Glu) which was identified frequently in the previous studies. A larger sample size is necessary for describing different pathogenic variants and understanding the phenotype-genotype correlations.

Identifying variants and their pathogenicity in inherited diseases is important for widening the disease-causing mutations and future treatment options.Two novel variants (c.3855_3856dup, c.5910_5912dup) were described in a cohort with Stargardt disease.The most common variants could be different in ethnic groups.The variant c.52C>T p.(Arg18Trp) was the most common variant besides the c.5882G>A p.(Gly1961Glu) which was frequently identified in the previous studies.Describing different pathogenic variants and clinical findings of the patients is important for understanding the phenotype-genotype correlations.

Frequency of RPE65 Gene Mutation in Patients with Hereditary Retinal Dystrophy.

Objectives: Hereditary retinal dystrophies are a rare group of diseases which are heterogeneous in genotype and phenotype and result in total blindness. One of the genetic defects that cause hereditary retinal dystrophy is mutation of the RPE65 gene. Genetic therapy studies in hereditary retinal dystrophies have increased in number recently, and important developments have been reported in these studies. Voretigene neparvovec-rzyl (Luxturna, Spark Therapeutics), a gene therapy drug for retinal dystrophy associated with RPE65 mutation, received Food and Drug Administration approval in 2017. This study aimed to investigate the frequency and clinical findings of patients with RPE65 gene defects, which may be amenable to genetic treatment. Materials and Methods: The data of patients diagnosed with hereditary retinal dystrophy who were followed up between 2017 and 2021 were retrospectively reviewed. Of these, 460 patients with genetic analysis results were included in the study. The clinical findings of patients with homozygous (biallelic) RPE65 mutation were screened. Results: RPE65 homozygous gene mutation was detected in only 11 of 460 cases (2.39%). Genetic results of the cases were presented in detail. The inheritance patterns of the cases were autosomal recessive. The demographic data and clinical findings were defined. Conclusion: RPE65 gene mutation is a very rare disorder. Genetic screening has gained importance with the emergence of gene therapy alternatives. New treatment methods are promising in cases for which there was no chance of a cure to date.

Quantitative analysis of early retinal vascular changes in type 2 diabetic patients without clinical retinopathy by optical coherence tomography angiography.

PURPOSE: To investigate the quantitative differences in optical coherence tomography angiography (OCTA) data between type 2 diabetes patients without clinically detectable diabetic retinopathy (DR) and healthy subjects. METHODS: Thirty-nine patients with type 2 diabetes without DR and 41 age- and sex-matched healthy controls were recruited. The vessel density and foveal avascular zone (FAZ) area in the superficial capillary plexus and deep capillary plexus were measured using Nidek RS-3000 Advance® and compared between patient cohorts. Foveal vessel density (%) and FAZ (%) were also calculated. RESULTS: A significant decrease in vessel density has been observed in the deep capillary plexus of the patients compared to healthy individuals (5.58 ± 0.98 mm2 versus 6.15 ± 0.89 mm2, p < 0.001). However, there were no significant differences in other parameters between cohorts (p > 0.05 in all parameters). Despite the decrease of deep capillary plexus density in the macular region, there was no significant change observed in foveal vessel density (p:0.44). It has also been observed that the duration of diabetes mellitus correlates with vessel density decrease in deep capillary plexus (R:-0.52; p < 0.001). In both groups, all parameters in deep capillary plexus were significantly higher than superficial capillary plexus (p < 0.001 for all parameters). CONCLUSIONS: OCTA can identify quantitative changes in DCP before the manifestation of clinically apparent retinopathy. DCP-VD reduction may be an earlier finding than FAZ enlargement. Despite the reduction of VD, FVD could be preserved for a certain period of time in DM patients.

Umbilical cord-derived mesenchymal stem cell implantation in patients with optic atrophy.

BACKGROUND: Optic nerve cells can be irreversibly damaged by common various causes. Unfortunately optic nerve and retinal ganglion cells have no regenerative capacity and undergo apoptosis in case of damage. In this study, our aim is to investigate the safety and efficacy of suprachoroidal umbilical cord-derived MSCs (UC-MSCs) implantation in patients with optic atrophy. METHODS: This study enrolled 29 eyes of 23 patients with optic atrophy who were followed in the ophthalmology department of our hospital. BCVA, anterior segment, fundus examination, color photography, and optical coherence tomography (OCT) were carried out at each visit. Fundus fluorescein angiography and visual field examination were performed at the end of the first, third, sixth months, and 1 year follow-up. RESULTS: After suprachoroidal UC-MSCs implantation there were statistically significant improvements in BCVA and VF results during 12 months follow-up (p < 0.05). When we evaluate the results of VF tests, the mean deviation (MD) value at baseline was -26.11 ± 8.36 (range -14.18 to -34.41). At the end of the first year it improved to -25.01 ± 8.73 (range -12.56 to -34.41) which was statistically significant (p < 0.05). When we evaluate the mean RNFL thickness measurements at baseline and at 12 month follow-up the results were 81.8 ± 24.9 µm and 76.6 ± 22.6 µm, respectively. There was not a significant difference between the mean values (p > 0.05). CONCLUSION: Stem cell treatment with suprachoroidal implantation of UCMSCs seems to be safe and effective in the treatment for optic nerve diseases that currently have no curative treatment options.

First Year Results of Suprachoroidal Adipose Tissue Derived Mesenchymal Stem Cell Implantation in Degenerative Macular Diseases.

BACKGROUND AND OBJECTIVES: This study shows the clinical data of 1-year follow-up of 8 patients with degenerative macular diseases who received suprachoroidal adipose tissue derived mesenchymal stem cell (ADMSC) implantation. METHODS AND RESULTS: This prospective, single-center, phase 1/2 study enrolled 8 eyes of 8 patients with degenerative macular diseases of various reasons who underwent suprachoroidal implantation of ADMSCs. All patients had severe visual field defects and severe visual loss. All patients had defective multifocal electroretinography (mf ERG). The worse eye of the patient was selected for the operation. Patients were evaluated on the first day, first month, sixth month and at 1 year postoperatively. Best corrected visual acuity (BCVA), anterior segment and fundus examination, color photography, optical coherence tomography (OCT) and visual field (VF) examination were carried out at each visit. Fundus fluorescein angiography (FFA) and mfERG recordings were performed at the end of the sixth months. All 8 patients completed the 1 year follow-up. None of them had any systemic or ocular complications. Seven of the patients experienced visual acuity improvement, visual field improvement and improvement in the mfERG recordings. We found choroidal thickening in OCT of the four treated eyes. CONCLUSIONS: Even though the sample size is small, stem cell treatment with suprachoroidal implantation of ADMSCs seems to be safe and the improvements were encouraging. To optimize the cell delivery technique and to evaluate the effects of this therapy on visual acuity and the quality of life of these patients, future studies with larger number of cases will be necessary.

Umbilical cord derived mesenchymal stem cell implantation in retinitis pigmentosa: a 6-month follow-up results of a phase 3 trial.

AIM: To investigate the efficacy and the safety of umbilical cord derived mesenchymal stem cell (UC-MSC) implantation in patients with retinitis pigmentosa (RP). METHODS: This prospective, single-center, phase 3 clinical study enrolled 124 eyes of 82 RP patients. The patients received 5 million UC-MSCs to the suprachoroidal area with a surgical procedure. Patients were evaluated on the 1st day, 1st, and 6th months postoperatively. Best corrected visual acuity (BCVA), anterior segment and fundus examinations, color photography, optical coherence tomography (OCT), and visual field (VF) tests were carried out at each visit. Fundus fluorescein angiography (FFA) and multifocal electroretinography (mfERG) recordings were performed at the end of the 6th month. Ocular and systemic adverse events of the surgical procedure were also noted. RESULTS: All of the 82 patients completed the 6-month follow-up period. None of them had any serious systemic or ocular complications. There were statistically significant improvements in BCVA and VF during the study (all P<0.05). The amplitudes of the P1 waves in the central areas showed significant improvements in mfERG recordings. There were also significant increases in implicit times of P1 waves in the central areas. CONCLUSION: Suprachoroidal administration of UC-MSCs has beneficial effect on BCVA, VF, and mfERG measurements during the 6-month follow-up period. Cell mediated therapy based on the secretion of growth factors (GFs) seems to be an effective and safe option for degenerative retinal diseases.

Effect of Transcorneal Electrical Stimulation on Patients with Retinitis Pigmentosa.

Purpose: In this study, the aim was to evaluate the safety of transcorneal electrical stimulation (TES) treatment in retinitis pigmentosa (RP) patients and to investigate the effect of TES to the visual acuity (VA), visual field (VF), and multifocal electroretinogram (mfERG) findings. Methods: Two hundred two eyes of 101 RP patients with different stages were studied. TES was applied for 30 min once a week for 8 consecutive weeks. Two hundred eyes of 100 RP patients were enrolled as control. After the 2-month TES therapy sessions, patients were followed for 4 months without treatment. Examinations were done at the baseline before TES treatment and 1 and 6 months after the treatment. Best-corrected VA (BCVA), color fundus photography, VF test, optical coherence tomography, and mfERG tests were done at each visit. Results: The mean BCVA and VF tests improved 1 month after the beginning of TES treatment and the improvements were statistically significant (P < 0.05). There was an improvement in p1 wave amplitude in rings 1, 2, and 3 at the first month. The latency of the p1 wave showed a statistically significant shortening in rings 1 and 2. These improvements partially disappeared at 6-month follow-up. There were no serious ocular side effects related to the therapy. Mild dry eye symptoms were observed, which were revealed by artificial tears. Conclusions: TES is a safe therapy without any serious advers effects. Although it can improve VA and VF of RP patients, the beneficial effects could be transient and repeated sessions can be necessary for maintaining the efficiency.

Six-month results of suprachoroidal adipose tissue-derived mesenchymal stem cell implantation in patients with optic atrophy: a phase 1/2 study.

PURPOSE: This prospective clinical case series aimed to investigate the safety and efficacy of suprachoroidal adipose tissue-derived mesenchymal stem cell (ADMSC) implantation in patients with optic nerve diseases. METHODS: This prospective, single-center, phase 1/2 study enrolled 4 eyes of 4 patients with optic atrophy of various reasons who underwent suprachoroidal implantation of ADMSCs. The best-corrected visual acuity (BCVA) in the study was HM at 1 m. The worse eye of the patient was operated. Patients were evaluated on the first day, first week, first month, third and sixth months postoperatively. BCVA, anterior segment and fundus examination, color photography, optical coherence tomography (OCT) and visual field examination were carried out at each visit. Fundus fluorescein angiography and multifocal electroretinography (mfERG) recordings were performed at the end of the first, third and sixth months and anytime if necessary during the follow-up. RESULTS: All 4 patients completed the six-month follow-up. None of them had any systemic or ocular complications. All of the patients experienced visual acuity improvement, visual field improvement and improvement in the mfERG recordings. We found choroidal thickening in OCT of the 4 patients. CONCLUSION: Even though the sample size is small, the improvements were still encouraging. Stem cell treatment with suprachoroidal implantation of ADMSCs seems to be safe and effective in the treatment for optic nerve diseases that currently have no curative treatment options.

Suprachoroidal Adipose Tissue-Derived Mesenchymal Stem Cell Implantation in Patients with Dry-Type Age-Related Macular Degeneration and Stargardt's Macular Dystrophy: 6-Month Follow-Up Results of a Phase 2 Study.

This prospective clinical case series aimed to investigate the safety and efficacy of suprachoroidal adipose tissue-derived mesenchymal stem cell (ADMSC) implantation in patients with dry-type age-related macular degeneration (AMD) and Stargardt's macular dystrophy (SMD). This study included four patients with advanced-stage dry-type AMD and four patients with SMD who underwent suprachoroidal implantation of ADMSCs. The best-corrected visual acuity (BCVA) in the study was 20/200. The worse eye of the patient was operated on. Patients were evaluated on the first day, first week, and first, third, and sixth months postoperatively. BCVA, anterior segment and fundus examination, color photography, fundus autofluorescence, optical coherence tomography, and visual field examination were carried out at each visit. Fundus fluorescein angiography and multifocal electroretinography (mf-ERG) recordings were performed at the end of the first, third, and sixth months and anytime if necessary during the follow-up. All eight patients completed the sixth month follow-up. None of them had any systemic or ocular complications. All of the eight patients experienced visual acuity improvement, visual field improvement, and improvement in mf-ERG recordings. Stem cell treatment with suprachoroidal implantation of ADMSCs seems to be safe and effective in the treatment of dry-type AMD and SMD.

Apo E gene polymorphism on development of diabetic nephropathy.

Type 2 diabetes causes premature morbidity and mortality due to the complications of atherosclerosis and diabetic nephropathy (DN). Polymorphism of Apo E gene is known to influence lipid metabolism. Apo E is polymorphic, consisting of three common isoforms (epsilon2, epsilon3 and epsilon4) encoded by three alleles (2, 3 and 4) in exon 4 on chromosome 19. The aim of this study was to investigate the effect of Apo E polymorphism as a prognostic risk factor for the development of DN. A total of 108 NIDDM patients were recruited from the Nephrology and Endocrinology Departments of our hospital. All subjects were divided into three groups: Group I: diabetes with nephropathy (n:37), group II: diabetes without nephropathy (n:71), group III: controls (n:46). Apo E genotypes were determined by real-time PCR. The epsilon4 allele frequency was significantly higher in-group I (10.8%) than in-group III (2.2%), (p < 0.05). In diabetics without nephropathy, the total cholesterol and LDL cholesterol levels were significantly lower in subjects with epsilon2 alleles than epsilon3 and epsilon4 alleles. In conclusion, the present prospective study indicates that the epsilon4 allele of the Apo E polymorphism is one of the prognostic risk factors involved in the development of DN with type 2 diabetes mellitus.