Akiko Hikoya

Two novel mutations in the EYS gene are possible major causes of autosomal recessive retinitis pigmentosa in the Japanese population.

Retinitis pigmentosa (RP) is a highly heterogeneous genetic disease including autosomal recessive (ar), autosomal dominant (ad), and X-linked inheritance. Recently, arRP has been associated with mutations in EYS (Eyes shut homolog), which is a major causative gene for this disease. This study was conducted to determine the spectrum and frequency of EYS mutations in 100 Japanese arRP patients. To determine the prevalence of EYS mutations, all EYS exons were screened for mutations by polymerase chain reaction amplification, and sequence analysis was performed. We detected 67 sequence alterations in EYS, of which 21 were novel. Of these, 7 were very likely pathogenic mutations, 6 were possible pathogenic mutations, and 54 were predicted non-pathogenic sequence alterations. The minimum observed prevalence of distinct EYS mutations in our study was 18% (18/100, comprising 9 patients with 2 very likely pathogenic mutations and the remaining 9 with only one such mutation). Among these mutations, 2 novel truncating mutations, c.4957_4958insA (p.S1653KfsX2) and c.8868C>A (p.Y2956X), were identified in 16 patients and accounted for 57.1% (20/35 alleles) of the mutated alleles. Although these 2 truncating mutations were not detected in Japanese patients with adRP or Lebers congenital amaurosis, we detected them in Korean arRP patients. Similar to Japanese arRP results, the c.4957_4958insA mutation was more frequently detected than the c.8868C>A mutation. The 18% estimated prevalence of very likely pathogenic mutations in our study suggests a major involvement of EYS in the pathogenesis of arRP in the Japanese population. Mutation spectrum of EYS in 100 Japanese patients, including 13 distinct very likely and possible pathogenic mutations, was largely different from the previously reported spectrum in patients from non-Asian populations. Screening for c.4957_4958insA and c.8868C>A mutations in the EYS gene may therefore be very effective for the genetic testing and counseling of RP patients in Japan.

Central Corneal Thickness in Japanese Children

PurposeTo determine the central corneal thickness (CCT) in Japanese children and to investigate the changes in CCT with increasing age.MethodsPachymetry was performed on 338 eyes of 169 patients undergoing eye muscle surgery under general anesthesia, and the intraocular pressure (IOP) was measured on 312 eyes of 156 of those same patients. Patients with abnormalities other than refractive errors and strabismus were excluded. Patients were divided into four groups: group 1, ≤1 year of age; group 2, 2–4; group 3, 5–9; and group 4, 10–18 years of age. Analysis of variance (ANOVA) was performed to determine the significance of the changes in CCT.ResultsThe average CCT of the right eye was 544.3 ± 36.9 μm. The CCT was thinner in group 1 than in groups 3 and 4 (ANOVA, P = 0.02). There was a positive but weak correlation between IOP and CCT (IOP = 6.253 + 0.014 × CCT; r2 = 0.047, P = 0.007).ConclusionsCCT reaches the adult thickness in Japanese children by age 5 years. The average CCT is thinner in Japanese children than in Caucasians but thicker than in African American children.

Magnetic Resonance Imaging of the Medial Rectus Muscle of Patients with Consecutive Exotropia after Medial Rectus Muscle Recession

PURPOSE To investigate the morphologic characteristics of the medial rectus muscle in patients with consecutive exotropia. DESIGN Retrospective, nonrandomized, interventional study. PARTICIPANTS AND CONTROLS Eleven eyes of 10 patients with consecutive exotropia were studied. Thirteen eyes of 13 age-matched normal subjects were studied as controls. METHODS All of the patients underwent an advancement of a previously operated medial rectus muscle. Patients were divided into 3 groups based on the insertion of the medial rectus muscle: Normally recessed stretched scar, and slipped muscle. MAIN OUTCOME MEASURES A comparison was made of the clinical findings, intraoperative findings, and distance from the limbus to the medial rectus muscle measured on magnetic resonance images among the groups. RESULTS The medial rectus of 4 eyes of 3 patients had normally recessed insertions and 7 eyes had abnormal insertions (3 stretched scars, 4 slipped muscles). The clinical findings were not different among the 3 groups. The magnetic resonance images showed that the medial rectus muscle was located closest to the limbus in the control subjects and most distant in the patients with a slipped muscle (P<0.005). The clinical findings in the patients with a stretched scar and with normally recessed were indistinguishable. CONCLUSIONS Magnetic resonance images of the medial rectus muscles of the control subjects and operated groups are significantly different morphologically. A slipped medial rectus muscle has characteristic magnetic resonance findings that are distinguishable from the muscle with normally recessed and stretched scar.

Novel RDH5 Mutation in Family with Mother Having Fundus Albipunctatus and Three Children with Retinitis Pigmentosa

Purpose: To identify mutations in the RDH5 gene in a family with a mother having fundus albipunctatus (FA) and 3 children with retinitis pigmentosa (RP). Methods: Ophthalmological examinations were performed to diagnose FA and RP. Mutational analysis of RDH5 was performed. Results/Conclusions: The mother was diagnosed with FA, and 3 children were diagnosed with RP. The probands mother, brother, and sister had a novel mutation c.689_690CT > GG in RDH5. The proband and mother had a previously reported mutation c.928delCinsGAAG. Consequently, the mothers FA was caused by compound heterozygous mutations. Further studies will be needed to determine the gene responsible for childrens RP.

Three novel mutations of the PAX6 gene in Japanese aniridia patients

AbstractMutations in the PAX6 gene of Japanese aniridia patients were analyzed. Four types of mutations including one known (474delC) and three novel (786_787ins10, 678_688del11 and 572_575delAATCins14) were found in six patients from four families. A patient with the mutation 572_575delAATCins14 also manifested VATER association. This is the first case of aniridia accompanied by VATER association. All of mutations found in this study are frameshift type, resulting in premature termination of translation. The database for PAX6 gene mutation has been made using a graphical data display system MutationView (http://mutview.dmb.med.keio.ac.jp/).

Novel GUCY2D Gene Mutations in Japanese Male Twins with Leber Congenital Amaurosis

Purpose. Leber congenital amaurosis (LCA), a genetically and clinically heterogeneous disease, is the earliest onset retinitis pigmentosa (RP) and is the most severe of hereditary retinal dystrophies. This study was conducted to investigate genetic and clinical features of LCA in a set of Japanese male twins with LCA. Methods. To identify causative mutations, 74 genes known to cause RP or LCA were examined by targeted-next generation sequencing (NGS). Targeted-NGS was performed using a custom designed Agilent HaloPlex target enrichment kit with Illumina Miseq sequencer. Identified potential pathogenic mutations were confirmed using Sanger sequencing. Clinical analyses were based on ophthalmic examination, fundus photography, and electroretinography (ERG). Results. Compound heterozygous GUCY2D mutations of novel splicing mutation c.2113+2_2113+3insT and novel missense mutation p.L905P were detected in both twins. Their father and mother were heterozygous for c.2113+2_2113+3insT and p.L905P, respectively. The twins had phenotypic features similar to those previously reported in patients with GUCY2D mutations. This included early childhood onset of visual loss, nystagmus, unrecordable ERG, photophobia, and hyperopia. Conclusions. To the best of our knowledge, this is the first report of genetic and clinical features of Japanese LCA twins with GUCY2D mutation, which were detected using targeted-NGS.

The first USH2A mutation analysis of Japanese autosomal recessive retinitis pigmentosa patients: a totally different mutation profile with the lack of frequent mutations found in Caucasian patients.

Retinitis pigmentosa (RP) is a highly heterogeneous genetic disease. The USH2A gene, which accounts for approximately 74–90% of Usher syndrome type 2 (USH2) cases, is also one of the major autosomal recessive RP (arRP) causative genes among Caucasian populations. To identify disease-causing USH2A gene mutations in Japanese RP patients, all 73 exons were screened for mutations by direct sequencing. In total, 100 unrelated Japanese RP patients with no systemic manifestations were identified, excluding families with obvious autosomal dominant inheritance. Of these 100 patients, 82 were included in this present study after 18 RP patients with very likely pathogenic EYS (eyes shut homolog) mutations were excluded. The mutation analysis of the USH2A revealed five very likely pathogenic mutations in four patients. A patient had only one very likely pathogenic mutation and the others had two of them. Caucasian frequent mutations p.C759F in arRP and p.E767fs in USH2 were not found. All the four patients exhibited typical clinical features of RP. The observed prevalence of USH2A gene mutations was approximately 4% among Japanese arRP patients, and the profile of the USH2A gene mutations differed largely between Japanese patients and previously reported Caucasian populations.

A case of aniridia with unilateral Peters anomaly.

Aniridia is an autosomal-dominant, panocular, congenital anomaly transmitted with high penetrance and largely caused by mutations in the PAX6 gene. Although Peters anomaly may also be caused by mutations in PAX6, there has not to our knowledge been a report of aniridia associated with lens displacement into the anterior chamber and lenticular-corneal attachment. We report a child with aniridia and Peters anomaly associated with a PAX6 gene mutation.

Visual Outcomes in Japanese Patients with Retinitis Pigmentosa and Usher Syndrome Caused by USH2A Mutations

ABSTRACT Purpose: EYS and USH2A are the most common causative genes for retinitis pigmentosa (RP) in Japan. We determined the clinical outcomes for USH2A-related non-syndromic RP or Usher syndrome type II (USH2). Methods: Two non-syndromic RP and 11 USH2 patients with previously identified USH2A mutations were included. Their complete history and medical records were collected using standard procedures. Visual fields and acuity were compared with those of patients with EYS mutations. Clinical analyses were based on ophthalmic and otolaryngologic examinations. Results: In all patients, the fundus displayed changes typical of RP. Most patients showed relatively well-preserved visual acuity in their thirties or forties, with rapid deterioration in their fifties. Concentric constriction started in the twenties or thirties, and no effective residual visual field was observed after the fifties. Conclusions: The visual outcome for non-syndromic RP or USH2 patients with USH2A mutations is consistent with that for RP patients with EYS mutations.

Interaction between optineurin and the bZIP transcription factor NRL.

Although the gene encoding optineurin (OPTN) is a causative gene for glaucoma and amyotrophic lateral sclerosis, it is ubiquitously expressed in all body tissues, including the retina. To study the function of OPTN in retinal ganglion cells as well as the whole retina, we previously isolated OPTN‐interacting proteins and identified the gene encoding the bZIP transcription factor neural retina leucine zipper (NRL), which is a causative gene for retinitis pigmentosa. Herein, we investigated the binding between OPTN and NRL proteins in HeLaS3 cells. Co‐expression of HA‐tagged NRL and FLAG‐tagged OPTN in HeLaS3 cells followed by immunoprecipitation and Western blotting with anti‐tag antibodies demonstrated the binding of these proteins in HeLaS3 cells, which was confirmed by proximity ligation assay. NRL is the first OPTN‐binding protein to show eye‐specific expression. A series of partial‐deletion OPTN plasmids demonstrated that the tail region (423–577 amino acids [aa]) of OPTN was necessary for binding with NRL. Immunostaining showed that Optn (rat homologue of OPTN) was expressed in rat photoreceptors and localised in the cytoplasm of photoreceptor cells. This is a novel demonstration of Optn expression in photoreceptor cells. OPTN was not detected in photoreceptor nuclei under our experimental conditions. Further analyses are necessary to elucidate the function of OPTN and the significance of its possible binding with NRL in photoreceptor cells.