Disease-specific variant interpretation highlighted the genetic findings in 2325 Japanese patients with retinitis pigmentosa and allied diseases.

BACKGROUND: As gene-specific therapy for inherited retinal dystrophy (IRD) advances, unified variant interpretation across institutes is becoming increasingly important. This study aims to update the genetic findings of 86 retinitis pigmentosa (RP)-related genes in a large number of Japanese patients with RP by applying the standardised variant interpretation guidelines for Japanese patients with IRD (J-IRD-VI guidelines) built upon the American College of Medical Genetics and Genomics and the Association for Molecular Pathology rules, and assess the contribution of these genes in RP-allied diseases. METHODS: We assessed 2325 probands with RP (n=2155, including n=1204 sequenced previously with the same sequencing panel) and allied diseases (n=170, newly analysed), including Usher syndrome, Leber congenital amaurosis and cone-rod dystrophy (CRD). Target sequencing using a panel of 86 genes was performed. The variants were interpreted according to the J-IRD-VI guidelines. RESULTS: A total of 3564 variants were detected, of which 524 variants were interpreted as pathogenic or likely pathogenic. Among these 524 variants, 280 (53.4%) had been either undetected or interpreted as variants of unknown significance or benign variants in our earlier study of 1204 patients with RP. This led to a genetic diagnostic rate in 38.6% of patients with RP, with EYS accounting for 46.7% of the genetically solved patients, showing a 9% increase in diagnostic rate from our earlier study. The genetic diagnostic rate for patients with CRD was 28.2%, with RP-related genes significantly contributing over other allied diseases. CONCLUSION: A large-scale genetic analysis using the J-IRD-VI guidelines highlighted the population-specific genetic findings for Japanese patients with IRD; these findings serve as a foundation for the clinical application of gene-specific therapies.

Genotypes and clinical features of RHO-associated retinitis pigmentosa in a Japanese population.

PURPOSE: To report the genotypes and clinical features of RHO-associated retinitis pigmentosa (RHO-RP) in the Kyushu region of Japan. STUDY DESIGN: Retrospective, single-center study. METHODS: Sixteen RP patients with pathogenic RHO variants seen at Kyushu University Hospital were investigated. Clinical data including age, best-corrected visual acuity (BCVA) in logarithm of the minimum angle of resolution (logMAR) units, visual field, fundus photography, and optical coherence tomography were retrospectively obtained. Visual outcomes were compared between classical and sector phenotypes and among genetic variants. RESULTS: The mean age at the first visit was 54.0 ± 15.7 years, with a mean follow-up of 7.6 ± 4.0 years. Fourteen patients (87.5%) showed the classical RP phenotype, of whom four were associated with p.[Pro23Leu] and two had p.[Pro347Leu] variants. In addition, two patients with the sector phenotype harbored p.[Ala164Val] variants. Among the classical RHO-RP patients, the mean BCVA decreased from 0.60 to 1.08 logMAR over the follow-up period (7.4 ± 4.1 years) whereas BCVA was preserved at 0.04 logMAR in sector RHO-RP patients (9.0 ± 3.0 years). Genotype-to-phenotype analysis demonstrated that p.[Pro347Leu] was associated with severe vision loss at an earlier age. Macular complications such as epiretinal membrane and cystoid macular edema were observed in 5 classical RHO-RP patients. CONCLUSION: p.[Pro23Leu], but not p.[Pro23His], was a frequent variant causing RHO-RP in the Kyushu region of Japan. As reported in previous studies, patients with the p.[Pro347Leu] variant showed a more severe phenotype, and variants causing sector RHO-RP were associated with a good prognosis.

Abilities of circumpapillary retinal nerve fiber layer thickness and vascular density to discriminate stages in primary open-angle glaucoma.

PURPOSE: To clarify the abilities of circumpapillary retinal nerve fiber layer thickness (cpRNFLT) obtained by optical coherence tomography (OCT) and circumpapillary vessel density (cpVD) measured by OCT-angiography to distinguish different stages in primary open-angle glaucoma determined by 24-2 or 30-2 static visual field (VF) testing. METHODS: This retrospective study includes 25 healthy normal eyes of 25 subjects and 87 primary open-angle glaucoma eyes of 87 patients. Areas under the receiver operating characteristic curves (AUROC) were evaluated for determining glaucoma stages using cpRNFLT and cpVD. The absolute errors of the estimated mean total deviation (mTD) using optimal models with cpRNFLT and cpVD were also compared. RESULTS: The AUROCs for discriminating glaucomatous eyes from normal eyes was significantly higher for cpRNFLT than the respective AUROCs for cpVD (0.969 [95% CI 0.939 to 0.998] vs. 0.872 [95% CI 0.806 to 0.938], p = 0.006), whereas cpVD had significantly higher AUROC for discriminating severe glaucoma eyes from moderate glaucoma eyes than cpRNFLT (0.771 [95% CI 0.655 to 0.886] vs. 0.578 [95% CI 0.420 to 0.736], p = 0.022). The mean absolute error in estimating mTD using both cpRNFLT and cpVD was significantly less than the error using cpRNFLT alone (4.56 ± 3.76 dB vs. 5.39 ± 4.00 dB, p = 0.027). CONCLUSION: Our results suggest that cpVD is better for follow-ups after moderate stage. The combination of cpRNFLT and cpVD may improve VF estimation compared to cpRNFLT alone.

Pathogenic variants of MFRP and PRSS56 genes are major causes of nanophthalmos in Japanese patients.

BACKGROUND: Nanophthalmos (NNO) is a rare condition with significantly shorter axial length than normal. Several genes are known to cause NNO, among them the MFRP and PRSS56 genes have been reported to cause majority of NNOs. The purpose of this study was to determine the genetic basis of Japanese patients with NNO. MATERIALS AND METHODS: We studied seven patients with NNO. Whole exome sequencing (WES) and Sanger sequencing were performed to determine the variants causing the NNO. We also reviewed the medical charts of the patients to determine the phenotype of these seven patients. RESULTS: WES revealed that four patients from three families carried homozygous frameshift variants of the PRSS56 gene (c.1066dupC). Two novel variants of the MFRP gene were detected in the other two patients: one proband had a homozygous missense variant (c.1486 G>A) and the other had a compound heterozygous variant (c.1486 G>A and c.662_663insT). The axial length of the eight eyes with the PRSS56 variant was 15.69 ± 0.48 mm (mean ± SD) and that for the 4 eyes with the MFRP variant was 15.63 ± 0.69 mm. Three of the six cases with the PRSS56 or MFRP variant had the uveal effusion syndrome. CONCLUSIONS: NNOs in Japanese patients are caused by variants of the PRSS56 and MFRP genes as in other ethnic populations. In addition, two new variants of the MFRP gene were found in our cohort. The phenotypes and anomalies in Japanese patients with NNO were similar to those reported for other ethnic populations.

Association Between Torque Teno Virus and Systemic Immunodeficiency in Patients With Uveitis With a Suspected Infectious Etiology.

PURPOSE: To determine the correlation between the presence of torque teno virus (TTV) in the aqueous humor of patients with uveitis and clinical information, including immunodeficiency history. DESIGN: Multicenter, retrospective, cross-sectional study. METHODS: Fifty-eight patients with uveitis with a suspected infectious etiology and 24 controls with cataract or age-related macular degeneration were included. We used quantitative polymerase chain reaction to test all subjects for TTV and multiplex polymerase chain reaction to test uveitis subjects for common ocular pathogens. When possible, both serum and aqueous humor samples were tested. Ocular TTV positivity was compared with age, sex, and a history of systemic immunodeficiency with logistic analysis. RESULTS: Ocular TTV positivity was found in 23%, 11%, and 0% of patients with herpetic uveitis, nonherpetic uveitis, and controls, respectively. Among patients with herpes infection, positivity for ocular TTV was found in 43%, 8%, 14%, and 50% of patients with cytomegalovirus retinitis, iridocyclitis, acute retinal necrosis, and Epstein-Barr virus-positive uveitis, respectively. Patients with cytomegalovirus retinitis showed a significantly higher rate of ocular TTV infection than controls (P = .008). Serum analysis revealed TTV positivity in 90% of patients with uveitis and in 100% of controls. Age- and gender-adjusted logistic analysis revealed a correlation between ocular TTV positivity and systemic immunodeficiency (P = .01), but no correlations between ocular TTV and age, gender, or viral pathogenic type. CONCLUSIONS: These findings suggest that positivity for ocular TTV was correlated with a clinical history of systemic immunodeficiency.

NOTCH2NLC GGC repeat expansion causes retinal pathology with intranuclear inclusions throughout the retina and causes visual impairment.

The retinal pathology of genetically confirmed neuronal intranuclear inclusion disease (NIID) is yet unknown. We report the ocular findings in four NIID patients with NOTCH2NLC GGC repeat expansion to investigate the pathology of retinopathy. All four NIID patients were diagnosed by skin biopsy and NOTCH2NLC GGC repeat analysis. Ocular findings in patients with NIID were studied using fundus photographs, optical coherence tomographic images (OCT), and full-field electroretinograms (ERGs). The histopathology of the retina was studied on autopsy samples from two cases with immunohistochemistry. All patients had an expansion of the GGC repeat (87-134 repeats) in the NOTCH2NLC. Two patients were legally blind and had been diagnosed with retinitis pigmentosa prior to the diagnosis of NIID and assessed with whole exome sequencing to rule out comorbidity with other retinal diseases. Fundus photographs around the posterior pole showed chorioretinal atrophy in the peripapillary regions. OCT showed thinning of the retina. ERGs showed various abnormalities in cases. The histopathology of autopsy samples showed diffusely scattered intranuclear inclusions throughout the retina from the retinal pigment epithelium to the ganglion cell layer, and optic nerve glial cells. And severe gliosis was observed in retina and optic nerve. The NOTCH2NLC GGC repeat expansion causes numerous intranuclear inclusions in the retina and optic nerve cells and gliosis. Visual dysfunction could be the first sign of NIID. We should consider NIID as one of the causes of retinal dystrophy and investigate the GGC repeat expansion in NOTCH2NLC.

Assessment of factors affecting flicker ERGs recorded with RETeval from data obtained from health checkup screening.

PURPOSE: To determine the factors significantly associated with the amplitudes and implicit times of the flicker electroretinograms (ERGs) recorded with the RETeval system by analyzing the comprehensive data obtained during a health checkup screening. METHODS: Flicker ERGs were recorded with the RETeval system from 373 individuals who had a normal fundus and optical coherence tomography images. The sex, age, anthropometric, ophthalmologic, and hematologic data were collected from all participants who were 40- to 89-years-of-age. Univariable and multivariable linear mixed effects regression analyses were performed to identify factors that were significantly associated with the implicit times and amplitudes of the RETeval flicker ERGs. RESULTS: Univariable linear mixed effects regression analysis showed significant correlations between the implicit times and the best-corrected visual acuity, the age, the axial length, the blood sugar level, and the blood urea nitrogen level. Analyses by multivariable linear mixed effects regression identified that the axial length (ß = 0.28), the age (ß = 0.24), and the blood sugar level (ß = 0.092) were three independent factors that were significantly correlated with the implicit times of the RETeval flicker ERGs. Univariable linear mixed effects regression analysis also showed significant correlations between the amplitudes of the RETeval flicker ERGs and the age, the platelet count, and the creatinine level. Multivariable linear mixed effects regression models identified the age (ß = -0.092), the platelet count (ß = 0.099), and the creatinine level (ß = -0.12) as three independent factors that were significantly correlated with the amplitudes of the RETeval flicker ERGs. However, the smoking habits, body mass index, and the blood pressure were not significantly correlated with either the implicit times or amplitudes of the RETeval flicker ERGs. CONCLUSIONS: Our results indicate that the age and some ophthalmologic and hematologic findings but not the anthropometric findings were significantly associated with the implicit times and amplitudes of the RETeval flicker ERGs. Thus, clinicians should remember these factors when analyzing the RETeval flicker ERGs.

ASSESSMENTS OF MACULAR FUNCTION BY FOCAL MACULAR ELECTRORETINOGRAPHY AND STATIC PERIMETRY IN EYES WITH RETINITIS PIGMENTOSA.

PURPOSE: To assess the macular function by focal macular electroretinography and static perimetry in eyes with retinitis pigmentosa. METHODS: Eighty-eight eyes of 88 retinitis pigmentosa patients were analyzed. The relationships between the focal macular electroretinography components and the mean deviations (MDs) of the Humphrey Field Analyzer 10-2 were determined. Spectral-domain optical coherence tomography was used to determine the integrity of the ellipsoid zone (EZ) and the interdigitation zone. RESULTS: Forward-backward stepwise regression analyses showed that the amplitudes (r = 0.45, P < 0.01) and implicit times (r = -0.29, P < 0.01) of the b-waves were significantly correlated with the MDs. Some of the eyes had reduced b-wave amplitudes (<1.0 µ V) and disrupted interdigitation zone, despite having a better MD (≥ -10.0 dB) and intact EZ. Subgroup analyses of eyes with better MD (≥ -10.0 dB) showed that the EZ width was correlated with the MDs but not with the b-wave amplitude. The thickness of the EZ-retinal pigment epithelium as an alternative indicator of interdigitation zone was correlated with the b-wave amplitude (r = 0.32, P = 0.04) but not with the MDs (r = -0.10, P = 0.53). CONCLUSION: The fact that the focal macular electroretinography amplitudes are reduced before the shortening of the EZ in the early stage of retinitis pigmentosa indicates that the focal macular electroretinography amplitudes are an earlier indicator of macular dysfunction than the Humphrey Field Analyzer 10-2 findings.

Likely pathogenic structural variants in genetically unsolved patients with retinitis pigmentosa revealed by long-read sequencing.

Despite the successful identification of causative genes and genetic variants of retinitis pigmentosa (RP), many patients have not been molecularly diagnosed. Our recent study using targeted short-read sequencing showed that the proportion of carriers of pathogenic variants in EYS, the cause of autosomal recessive RP, was unexpectedly high in Japanese patients with unsolved RP. This result suggested that causative genetic variants, which are difficult to detect by short-read sequencing, exist in such patients. Using long-read sequencing technology (Oxford Nanopore), we analysed the whole genomes of 15 patients with RP with one heterozygous pathogenic variant in EYS detected in our previous study along with structural variants (SVs) in EYS and another 88 RP-associated genes. Two large exon-overlapping deletions involving six exons were identified in EYS in two patients with unsolved RP. An analysis of an independent patient set (n=1189) suggested that these two deletions are not founder mutations. Our results suggest that searching for SVs by long-read sequencing in genetically unsolved cases benefits the molecular diagnosis of RP.

Circulating inflammatory monocytes oppose microglia and contribute to cone cell death in retinitis pigmentosa.

Retinitis pigmentosa (RP) is an intractable inherited disease that primarily affects the rods through gene mutations followed by secondary cone degeneration. This cone-related dysfunction can lead to impairment of daily life activities, and ultimately blindness in patients with RP. Paradoxically, microglial neuroinflammation contributes to both protection against and progression of RP, but it is unclear which population(s) - tissue-resident microglia and/or peripheral monocyte-derived macrophages (mφ) - are implicated in the progression of the disease. Here we show that circulating blood inflammatory monocytes (IMo) are key effector cells that mediate cone cell death in RP. Attenuation of IMo and peripherally engrafted mφ by Ccl2 deficiency or immune modulation via intravenous nano-particle treatment suppressed cone cell death in rd10 mice, an animal model of RP. In contrast, the depletion of resident microglia by a colony-stimulating factor 1 receptor inhibitor exacerbated cone cell death in the same model. In human patients with RP, IMo was increased and correlated with disease progression. These results suggest that peripheral IMo is a potential target to delay cone cell death and prevent blindness in RP.

Ablation of Ctrp9, Ligand of AdipoR1, and Lower Number of Cone Photoreceptors in Mouse Retina.

Purpose: C1q/TNF-related protein (CTRP) 9 is one of the adiponectin paralogs, and a genetic ablation of its receptor, AdipoR1, is known to cause retinal degeneration. The purpose of this study was to determine the role played by CTRP9 in the retina. Methods: The retinas of Ctrp9 gene knockout (KO) and wild type (WT) mice were examined by electroretinography (ERG), histology, RNA sequencing, and quantitative real-time PCR. Results: The amplitude of the photopic ERG elicited by the maximum stimulus intensity was smaller by 40% in the Ctrp9 KO mice than in WT mice at 8 weeks of age. However, the photopic ERGs was not reduced from 8 weeks to 6 months of age. The amplitudes of the scotopic ERGs were not reduced in the Ctrp9 KO mice at 8 weeks and 6 months of age. No distinct histological abnormalities were found in the retinal sections but the density of peanut agglutinin-stained cells in the retinal flat mount of KO mice was reduced to about 70% of that of WT mice. Genomewide RNA sequencing of the retina revealed the absence of the expression of CTRP9 in both KO and WT mice. RNA sequencing and quantitative real-time PCR analysis showed that the expressions of the transcripts of genes expressed in cones, Opn1sw, Opn1mw, Gnat2, and Cnga3, were reduced in the KO mice retina, however, the degree of expression of the transcripts in rods was not significantly reduced. Conclusions: CTRP9 is released ectopically from other tissues, and it regulates the number of cones in the mouse retinas.

RECURRENCE RATE OF CYSTOID MACULAR EDEMA WITH TOPICAL DORZOLAMIDE TREATMENT AND ITS RISK FACTORS IN RETINITIS PIGMENTOSA.

PURPOSE: To investigate the rate of the recurrence of cystoid macular edema (CME) secondary to retinitis pigmentosa (RP) after the initiation of topical dorzolamide and the recurrence risk factors. METHODS: We retrospectively analyzed the data of RP patients at Kyushu University Hospital. We included patients who showed a treatment response to 1.0% topical dorzolamide. The day of treatment initiation was set as the baseline. Topical dorzolamide treatment was continued during the follow-up. The recurrence of CME (defined as a >20% increase in central subfield thickness compared to previous visit, or a central subfield thickness value that exceed baseline value) was evaluated at each follow-up visit. Risk factors for RP-CME recurrence were analyzed by Cox proportional hazards modeling. A Kaplan-Meier survival analysis was used to evaluate the time to recurrent RP-CME. RESULTS: Forty RP-CME patients showed a treatment response to topical dorzolamide. During the mean 3.9-year follow-up, 14 patients exhibited recurrence; its rate was 15.6%, 34.7%, and 48.7% at 1, 3, and 5 years, respectively. A high baseline central subfield thickness was significantly associated with recurrent (hazard ratio 1.11, 95% CI: 1.05-1.18, P = 0.0004). CONCLUSION: The recurrence rate of RP-CME increased with time. A high baseline central subfield thickness value was a risk factor for recurrence.

Clinical findings in eyes with BEST1-related retinopathy complicated by choroidal neovascularization.

PURPOSE: To determine the characteristics of eyes diagnosed with Best vitelliform macular dystrophy (BVMD) and autosomal recessive bestrophinopathy (ARB) complicated by choroidal neovascularization (CNV). METHODS: This was a retrospective, multicenter observational case series. Fourteen genetically confirmed BVMD patients and 9 ARB patients who had been examined in 2 ophthalmological institutions in Japan were studied. The findings in a series of ophthalmic examinations including B-scan optical coherence tomography (OCT) and OCT angiography (OCTA) were reviewed. RESULTS: CNV was identified in 5 eyes (17.9%) of BVMD patients and in 2 eyes (11.1%) of ARB patients. Three of 5 eyes with BVMD were classified as being at the vitelliruptive stage and 2 eyes at the atrophic stage. The CNV in 2 BVMD eyes were diagnosed as exudative because of acute visual acuity reduction, retinal hemorrhage, and intraretinal fluid, while the CNV in 3 BVMD eyes and 2 ARB eyes were diagnosed as non-exudative. The visual acuity of the two eyes with exudative CNV did not improve despite anti-VEGF treatments. None of the eyes with non-exudative CNV had a reduction of their visual acuity for at least 4 years. All of the CNV were located within hyperreflective materials which were detected in 16 eyes (57.1%) of the BVMD eyes and in 7 eyes (38.9%) of the ARB eyes. CONCLUSIONS: CNV is a relatively common complication in BEST1-related retinopathy in Asian population as well. The prognosis of eyes with exudative CNV is not always good, and OCTA can detect CNV in eyes possessing hyperreflective materials.

Long-term Outcomes of Cataract Surgery in Patients with Retinitis Pigmentosa.

PURPOSE: To investigate the long-term outcomes of cataract surgery in patients with retinitis pigmentosa (RP). DESIGN: Retrospective, observational study. PARTICIPANTS: Sixty-four patients with typical RP (22 men, 42 women; average age, 62.8 ± 10.1 years) who underwent cataract surgery at Kyushu University Hospital between May 2007 and October 2015 and were followed up for ≥3 years after the surgery. METHODS: Differences between presurgery and postsurgery visual function, including best-corrected visual acuity (BCVA) and parameters in the Humphrey field analyzer (HFA) examination using the central 10-2 program, were investigated. The presurgery conditions of the foveal ellipsoid zone (EZ) were classified into 3 grades (grade 1: invisible; grade 2: abnormal; grade 3: normal) based on OCT findings. MAIN OUTCOME MEASURES: BCVA, the retinal sensitivity in the HFA 10-2 test. RESULTS: Cataract surgery was performed in 96 eyes, with an average follow-up period of 5.8 ± 2.4 years. The mean presurgery BCVA was 0.64 ± 0.52 logarithm of the minimum angle of resolution (logMAR), and the final postsurgery BCVA was 0.61 ± 0.67 logMAR (P = 0.57). Significant improvement in the postsurgery BCVA was observed only in eyes with preserved foveal EZ (grade 3) (P < 0.01). In 62 eyes of 45 patients who underwent the HFA 10-2 test, the mean values of deviation, macular sensitivity, and foveal sensitivity at the final visit were significantly decreased compared with preoperative values (P < 0.01), whereas those in grade 3 eyes did not change significantly after the surgery (P = 0.13). CONCLUSIONS: In the long-term course after cataract surgery in patients with RP, many patients experienced vision loss with progression of the disease. The preoperative finding of preserved foveal EZ was associated with a better visual prognosis, suggesting that EZ evaluation is useful for predicting the long-term visual outcome of cataract surgery in patients with RP.

Complete congenital stationary night blindness associated with a novel NYX variant (p.Asn216Lys) in middle-aged and older adult patients.

BACKGROUND: Complete congenital stationary night blindness (CSNB) is a retinal disorder thought to be non-progressive. The purpose of this study was to characterize the clinical and genetic findings of middle-aged and older adult patients with X-linked complete CSNB. METHODS: Three male CSNB patients (aged 62, 72, and 51 years) and one unaffected female carrier in a Japanese family were included in this study. Whole-exome sequencing (WES) was performed to determine the disease-causing variants. Co-segregation was confirmed in the family members. We performed a comprehensive ophthalmic examination on each patient. RESULTS: In the 62-year-old patient, a novel hemizygous variant (c.648 C > A; p.Asn216Lys) of the NYX gene was identified by WES analysis. The other two patients carried the variant hemizygously, and the unaffected carrier harbored the variant heterozygously. The clinical and electroretinography (ERG) findings were very similar among all three patients. Fundus images exhibited high myopic chorioretinal atrophy with long axial length. Ultra-wide field fundus autofluorescence images showed no retinal degenerative changes except for changes resulting from high myopia and previous retinal diseases. The ERG findings showed no response in rod ERG, electronegative configuration with preserved a-waves in standard/bright-flash ERG, and preserved responses in cone and 30-Hz flicker ERG, which were compared with age-matched controls with high myopia. CONCLUSIONS: We identified a novel missense NYX variant in a Japanese family with complete CSNB. Our clinical findings indicated that photoreceptor mediated ERG responses are well preserved even in middle-aged and older adult patients.

Regional differences in genes and variants causing retinitis pigmentosa in Japan.

PURPOSE: To investigate the regional differences in the genes and variants causing retinitis pigmentosa (RP) in Japan STUDY DESIGN: Retrospective multicenter study METHODS: In total, 1204 probands of each pedigree clinically diagnosed with nonsyndromic RP were enrolled from 5 Japanese facilities. The regions were divided into the Tohoku region, the Kanto and Chubu regions, and the Kyushu region according to the location of the hospitals where the participants were enrolled. We compared the proportions of the causative genes and the distributions of the pathogenic variants among these 3 regions. RESULTS: The proportions of genetically solved cases were 29.4% in the Tohoku region (n = 500), 29.6% in the Kanto and Chubu regions (n = 196), and 29.7% in the Kyushu region (n = 508), which did not differ statistically (P = .99). No significant regional differences in the proportions of each causative gene in genetically solved patients were observed after correction by multiple testing. Among the 29 pathogenic variants detected in all 3 regions, only p.(Pro347Leu) in RHO was an autosomal dominant variant; the remaining 28 variants were found in autosomal recessive genes. Conversely, 78.6% (275/350) of the pathogenic variants were detected only in a single region, and 6 pathogenic variants (p.[Asn3062fs] in EYS, p.[Ala315fs] in EYS, p.[Arg872fs] in RP1, p.[Ala126Val] in RDH12, p.[Arg41Trp] in CRX, and p.[Gly381fs] in PRPF31) were frequently found in ≥ 4 patients in the single region. CONCLUSION: We observed region-specific pathogenic variants in the Japanese population. Further investigations of causative genes in multiple regions in Japan will contribute to the expansion of the catalog of genetic variants causing RP.

Genotype and Long-term Clinical Course of Bietti Crystalline Dystrophy in Korean and Japanese Patients.

PURPOSE: To investigate the genotype and long-term clinical phenotype of patients with Bietti crystalline dystrophy (BCD) in Korea and Japan. DESIGN: Retrospective case series. PARTICIPANTS: We analyzed 62 patients with clinical features of BCD who harbor pathogenic biallelic CYP4V2 variants in their homozygote or compound heterozygote. METHODS: Data were collected from patient charts, including age, best-corrected visual acuity (BCVA), Goldmann perimetry results, fundus photography, OCT findings, fundus autofluorescence results, and electroretinography findings. We compared the clinical course of the patients with homozygous c.802-8_810de117insGC [exon7del], the most common mutation in the East Asian population, with those of the patients with other genotypes. MAIN OUTCOME MEASURES: Best-corrected visual acuity, visual field (VF), and their changes during follow-up. RESULTS: The mean age at the first visit was 55.2 years, with a mean follow-up of 7.1 years. The mean BCVAs at the first and last visits were 0.28 logarithm of the minimum angle of resolution (logMAR) and 0.89 logMAR, respectively. In genetic testing, c.802-8_810de117insGC was detected in 86 of 124 alleles of the patients, and 36 patients were homozygous for this mutation. The age, BCVA, VF area, central foveal thickness, and abnormal hypoautofluorescent area at either the first or last visit were not different between the exon7del homozygotes and the others. The mean BCVA changes per year were 0.089 logMAR in the exon7del homozygotes and 0.089 logMAR in the others. An age- and gender-adjusted linear regression analysis showed no association between the exon7del homozygote status and the rate of vision loss. Characteristic crystalline deposits in the posterior pole were generally observed in younger patients and disappeared over time along with progressive retinochoroidal atrophy. CONCLUSIONS: Patients with BCD and a homozygote for c.802-8_810de117insGC accounted for more than 50% of this cohort of Korean and Japanese patients, and the clinical effect of this deleterious variant was not severe in the spectrum of CYP4V2 retinopathy.

A hypomorphic variant in EYS detected by genome-wide association study contributes toward retinitis pigmentosa.

The genetic basis of Japanese autosomal recessive retinitis pigmentosa (ARRP) remains largely unknown. Herein, we applied a 2-step genome-wide association study (GWAS) in 640 Japanese patients. Meta-GWAS identified three independent peaks at P < 5.0 × 10-8, all within the major ARRP gene EYS. Two of the three were each in linkage disequilibrium with a different low frequency variant (allele frequency < 0.05); a known founder Mendelian mutation (c.4957dupA, p.S1653Kfs*2) and a non-synonymous variant (c.2528 G > A, p.G843E) of unknown significance. mRNA harboring c.2528 G > A failed to restore rhodopsin mislocalization induced by morpholino-mediated knockdown of eys in zebrafish, consistent with the variant being pathogenic. c.2528 G > A solved an additional 7.0% of Japanese ARRP cases. The third peak was in linkage disequilibrium with a common non-synonymous variant (c.7666 A > T, p.S2556C), possibly representing an unreported disease-susceptibility signal. GWAS successfully unraveled genetic causes of a rare monogenic disorder and identified a high frequency variant potentially linked to development of local genome therapeutics.

Longitudinal Changes of Macular Curvature in Patients with Retinitis Pigmentosa.

Purpose: To investigate the longitudinal changes of the macular curvature in eyes with retinitis pigmentosa (RP) and to determine the factors associated with the changes. Methods: We reviewed the medical charts of 107 RP patients, for whom the axial length of their right eyes ranged from 21.5 to 26.0 mm and who had had been followed by spectral-domain optical coherence tomography (OCT). The OCT images at the initial and the most recent examinations were compared. The mean curvature of Bruch's membrane within 6 mm of the central macula obtained from the OCT images was evaluated as the mean macular curvature index (MMCI). Changes in the MMCI and their relationships with other clinical factors, including the ellipsoid zone (EZ) width, were assessed. Results: The MMCI decreased significantly in the vertical OCT images, from -15.47 × 10-5 µm-1 to -16.36 × 10-5 µm-1 (P = 0.008) during the mean observation period of 3.4 ± 1.4 years (mean ± SD). This indicated that the macular shape became more concave. The change to a steeper shape was more prominent in eyes with less photoreceptor degeneration and for which the EZ width was preserved at >2000 µm. In three eyes, the MMCI increased markedly by >5 × 10-5 µm-1, and this was accompanied by absorption of the macular edema. Conclusions: The macular curvature in RP eyes becomes more concave in eyes with preserved EZ width. Translational Relevance: Longitudinal changes of the macular curvature in RP should be considered in future therapies, such as the implantation of the retinal prosthesis.

Changes of Serum Inflammatory Molecules and Their Relationships with Visual Function in Retinitis Pigmentosa.

Purpose: Retinal degeneration involves neuroinflammation, and pro-inflammatory cytokines/chemokines are markedly increased in the eyes of patients with retinitis pigmentosa (RP). In this study, we investigated the changes of serum cytokines/chemokines in RP, and their relationships with visual parameters. Methods: Forty-five consecutive patients with typical RP aged 20 to -39 years and 28 age-matched and gender-matched controls were included. Fifteen cytokines (interleukin [IL]-1α, IL-1ß, IL-2, IL-4, IL-5, IL-6, IL-10, IL-12p70, IL-13, 1L-15, IL-17, IL-23, interferon [IFN]-γ, and tumor necrosis factor [TNF]-α, TNF-ß) and 9 chemokines (eotaxin, growth-related oncogene [GRO]-α, I-309, IL-8, IFN-γ-inducible protein [IP]-10, monocyte chemotactic protein [MCP]-1, MCP-2, regulated activation normal T-cell expressed and secreted [RANTES], and thymus and activated regulated chemokine [TARC]) in the serum were simultaneously measured by a multiplexed immunoarray (Q-Plex). Relationships between these cytokines/chemokines and indices of central vision, such as visual acuity (VA), the values of static perimetry tests (Humphrey Field analyzer, the central 10-2 program), and optical coherence tomography measures were analyzed in the patients with RP. Results: Among the 15 cytokines and 9 chemokines, serum IL-8 and RANTES levels were significantly increased in patients with RP compared with controls (IL-8: P < 0.0001; RANTES: P < 0.0001). Among the elevated cytokines/chemokines, the levels of IL-8 were negatively correlated with VA (ρ = 0.3596 and P = 0.0165), and the average retinal sensitivity of four central points (ρ = -0.3691 and P = 0.0291), and 12 central points (ρ = -0.3491 and P = 0.0398), as well as the central subfield thickness (ρ = -0.3961 and P = 0.0094), and ellipsoid zone width (ρ = -0.3841 and P = 0.0120). Conclusions: Peripheral inflammatory response may be activated and serum IL-8 levels are associated with central vision in patients with RP.