Satoshi Katagiri

Whole Exome Analysis Identifies Frequent CNGA1 Mutations in Japanese Population with Autosomal Recessive Retinitis Pigmentosa

Objective The purpose of this study was to investigate frequent disease-causing gene mutations in autosomal recessive retinitis pigmentosa (arRP) in the Japanese population. Methods In total, 99 Japanese patients with non-syndromic and unrelated arRP or sporadic RP (spRP) were recruited in this study and ophthalmic examinations were conducted for the diagnosis of RP. Among these patients, whole exome sequencing analysis of 30 RP patients and direct sequencing screening of all CNGA1 exons of the other 69 RP patients were performed. Results Whole exome sequencing of 30 arRP/spRP patients identified disease-causing gene mutations of CNGA1 (four patients), EYS (three patients) and SAG (one patient) in eight patients and potential disease-causing gene variants of USH2A (two patients), EYS (one patient), TULP1 (one patient) and C2orf71 (one patient) in five patients. Screening of an additional 69 arRP/spRP patients for the CNGA1 gene mutation revealed one patient with a homozygous mutation. Conclusions This is the first identification of CNGA1 mutations in arRP Japanese patients. The frequency of CNGA1 gene mutation was 5.1% (5/99 patients). CNGA1 mutations are one of the most frequent arRP-causing mutations in Japanese patients.

Novel C8orf37 Mutations in Patients with Early-onset Retinal Dystrophy, Macular Atrophy, Cataracts, and High Myopia

ABSTRACT Purpose: More than 50 genes are reported as causative genes of autosomal recessive (ar) retinitis pigmentosa (RP) and cone-rod dystrophy (CRD). It is challenging to identify causative mutations for arRP and arCRD. The purpose of the present study was to investigate clinical and genetic features of two siblings with early-onset retinal dystrophy. Methods: Whole-exome sequencing was conducted for the two affected siblings and their unaffected brother and mother from a Japanese family. We performed complete ophthalmic examinations, including visual acuity, funduscopy, visual-field testing, electroretinography and optical coherence tomography. Results: Whole-exome sequencing analysis identified novel compound heterozygous mutations, a splice site mutation (c.374 + 2T > C in intron 4) and a deletion mutation (c.575delC [p.T192MfsX28] in exon 6) of chromosome 8 open reading frame 37 (C8orf37) gene, which encodes a ciliary protein, in both patients. The mother carried the truncating mutation, and the brother carried neither mutation. Ophthalmic examinations revealed diffuse retinal degeneration, macular atrophy, non-recordable electroretinography responses, cataracts, and high myopia in both patients, who could not be diagnosed with either RP or CRD because of the severe retinal degeneration and early onset disease. Longitudinal follow-up of the patients revealed highly progressive retinal degeneration, macular atrophy, and visual field loss. Conclusions: Recessive C8orf37 mutations have been identified in early to adolescent-onset arRP and arCRD with macular involvement. Our study identified two novel truncating mutations of the C8orf37 gene in siblings with early-onset retinal dystrophy, macular atrophy, cataracts, and high myopia.

RHO Mutations (p.W126L and p.A346P) in Two Japanese Families with Autosomal Dominant Retinitis Pigmentosa

Purpose. To investigate genetic and clinical features of patients with rhodopsin (RHO) mutations in two Japanese families with autosomal dominant retinitis pigmentosa (adRP). Methods. Whole-exome sequence analysis was performed in ten adRP families. Identified RHO mutations for the cosegregation analysis were confirmed by Sanger sequencing. Ophthalmic examinations were performed to evaluate the RP phenotypes. The impact of the RHO mutation on the rhodopsin conformation was examined by molecular modeling analysis. Results. In two adRP families, we identified two RHO mutations (c.377G>T (p.W126L) and c.1036G>C (p.A346P)), one of which was novel. Complete cosegregation was confirmed for each mutation exhibiting the RP phenotype in both families. Molecular modeling predicted that the novel mutation (p.W126L) might impair rhodopsin function by affecting its conformational transition in the light-adapted form. Clinical phenotypes showed that patients with p.W126L exhibited sector RP, whereas patients with p.A346P exhibited classic RP. Conclusions. Our findings demonstrated that the novel mutation (p.W126L) may be associated with the phenotype of sector RP. Identification of RHO mutations is a very useful tool for predicting disease severity and providing precise genetic counseling.

Novel RP1L1 Variants and Genotype-Photoreceptor Microstructural Phenotype Associations in Cohort of Japanese Patients With Occult Macular Dystrophy.

PURPOSE To determine the clinical and genetic characteristics of Japanese patients with occult macular dystrophy (OMD) in a nationwide multicenter study. METHODS Twenty-three patients from 21 families with clinically diagnosed OMD were studied at 10 institutions throughout Japan. Ophthalmologic examinations including spectral-domain optic coherence tomography were performed. Patients were classified into two phenotype groups: a classical group having both blurred ellipsoid zone and absence of interdigitation zone of the photoreceptors, and a nonclassical group lacking at least one of these two features. Whole-exome sequencing, direct sequencing, and in silico molecular analysis were performed to detect the pathogenic RP1L1 variants. Statistical associations between the phenotype and genotypes based on the presence of pathogenic RP1L1 variants were investigated. RESULTS There were 12 families with the classical findings and 9 families with the nonclassical findings. Nine pathogenic RP1L1 missense variants were identified in 12 families (57%) including three reported variants, namely, p.R45W, p.S1199C, and p.G1200A, and six novel variants, p.G221R, p.T1194M, p.T1196I, p.G1200D, p.G1200V, and p.V1201G. The pathogenic missense variants in seven families (33%) were located between amino acid numbers 1196 and 1201. A significant association was found between the photoreceptor microstructural phenotypes and molecular genotypes. CONCLUSIONS The spectrum of the morphologic phenotypes and pathogenic RP1L1 variants was documented in a well-characterized Japanese cohort with OMD. A unique motif including six amino acids (1196-1201) downstream of the doublecortin domain could be a hot spot for RP1L1 pathogenic variants. The significant association of the morphologic phenotypes and genotypes indicates that there are two types of pathophysiology underlying the occult macular dysfunction syndrome: a hereditary OMD with the classical phenotype (Miyakes disease), and a nonhereditary OMD-like syndrome with progressive occult maculopathy.

Congenital Achromatopsia and Macular Atrophy Caused by a Novel Recessive PDE6C Mutation (p.E591K)

Abstract Purpose: We have previously reported clinical features of two siblings, a sister with complete achromatopsia (ACHM) and a brother with incomplete ACHM, in a consanguineous Japanese family. With the current study, we intended to identify a disease-causing mutation in the siblings and to investigate why the phenotypes of the siblings differed. Methods: We performed a comprehensive ophthalmic examination for each sibling and parent. Whole-exome and Sanger sequencing were performed on genomic DNA. Molecular modeling was analyzed in an in silico study. Results: The ophthalmic examination revealed severe macular atrophy in the older female sibling at 30 years of age and mild macular atrophy in the brother at 26 years of age. The genetic analysis identified a novel homozygous PDE6C mutation (p.E591K) as the disease-causing allele in the siblings. Each parent was heterozygous for the mutation. Molecular modeling showed that the mutation could cause a conformational change in the PDE6C protein and result in reduced phosphodiesterase activity. We also identified an OPN1SW mutation (p.G79R), which is associated with congenital tritan deficiencies, in the sister and the father but not in the brother. Conclusions: A novel homozygous PDE6C mutation was identified as the cause of ACHM. In addition, we identified an OPN1SW mutation in the sibling with complete ACHM, which might explain the difference in phenotype (complete versus incomplete ACHM) between the siblings.

Mutation analysis of BEST1 in Japanese patients with Best's vitelliform macular dystrophy

Purpose To describe the clinical and genetic features of Japanese patients with Bests vitelliform macular dystrophy (BVMD). Patients and methods This study examined 22 patients, including 16 probands from 16 families with BVMD. Comprehensive ophthalmic examinations were performed, including dilated funduscopy, full-field electroretinography (ERG) and electro-oculography (EOG). BEST1 mutation analysis was performed by Sanger sequencing. Results All 16 probands exhibited characteristic BVMD fundus appearances, abnormal EOG, and normal ERG responses with the exception of one diabetic retinopathy proband. Genetic analysis identified 12 BEST1 variants in 13 probands (81%). Of these, 10 variants (p.T2A, p.R25W, p.F80L, p.V81M, p.A195V, p.R218H, p.G222E, p.V242M, p.D304del and p.E306D) have been previously reported in BVMD, while two variants (p.S7N and p.P346H) were novel, putative disease-causing variants. Single BEST1 variants were found in 12 probands. The one proband with compound heterozygous variants (p.S7N and p.R218H) exhibited typical BVMD phenotypes (pseudohypopyon stage and vitelliruptive stage in the right and left eyes, respectively). Conclusions Twelve different variants, two of which (p.S7N and p.P346H) were novel, were identified in the 13 Japanese families with BVMD. Compound heterozygous variants were found in one proband exhibiting a typical BVMD phenotype. Our results suggest that BEST1 variants do play a large role in Japanese patients with BVMD.

RPE65 Mutations in Two Japanese Families with Leber Congenital Amaurosis

Abstract Purpose: To investigate genetic and clinical features of patients with Leber congenital amaurosis (LCA) caused by RPE65 mutations. Methods: Five Japanese families with LCA were recruited. We performed complete ophthalmic examinations, with optical coherence tomography, fundus autofluorescence imaging, and full-field electroretinography (ERG). Genetic analysis was performed with whole-exome sequencing analysis and Sanger sequencing. Results: We identified RPE65 mutations in two unrelated LCA patients from two families. Case 1: A 5-month-old girl was diagnosed with LCA because of nystagmus, loss of vision and non-recordable ERG. She was the only one affected in her non-consanguineous family, and exhibited novel compound heterozygous RPE65 mutations (c.177C>G, p.H59Q and c.183_184insT, p.D62X). Case 2: A 30-year-old woman, who had night blindness and poor ocular pursuit during the first year of life, exhibited severe retinal degeneration and non-recordable ERG. She was the only affected in her non-consanguineous family, and showed a homozygous RPE65 mutation (c.1543C>T, p.R515W). Conclusions: By using whole-exome sequencing analysis, three RPE65 mutations were identified in two Japanese patients with LCA. This approach would be useful for identification of disease-causing mutations of LCA.

Retinal Structure and Function in Eyes with Optic Nerve Hypoplasia

We investigated retinal structure and function in eyes with optic nerve hypoplasia (ONH). Twenty-nine eyes of 18 patients with ONH and 21 eyes of 21 control patients were analyzed. Spectral-domain optical coherence tomography (SD-OCT), full-field electroretinography (FF-ERG), and focal macular ERG (FM-ERG) were performed. SD-OCT analysis of the macular region showed significant ganglion cells complex (GCC) thinning nasally and temporally (P < 0.05), but the thickness from the inner nuclear layer (INL) to the retinal pigment epithelium (RPE) became thinner only nasally (P < 0.05). SD-OCT analysis of the circumpapillary region showed significant thinning in the retinal nerve fiber layer and from the INL to the RPE (P < 0.05). The horizontal SD-OCT images showed variable foveal abnormalities. FF-ERG analysis showed significantly reduced amplitudes (P < 0.05) and preserved implicit time in the photopic negative response. The amplitudes and implicit times of the other FF-ERG components did not differ significantly. FM-ERG analysis showed significantly reduced amplitudes (P < 0.05) but preserved implicit times in all components. The current study showed the change of retinal structure and function in eyes with ONH compared with those with control, representing by decreased retinal ganglion cells (RGCs) and their axons, foveal abnormalities, and preserved peripheral retina except for the RGCs and their axons.

Electroretinographic effects of retinal dragging and retinal folds in eyes with familial exudative vitreoretinopathy.

We evaluated the retinal function of retinal dragging (Rdrag) and radial retinal folds (Rfolds) in eyes with familial exudative vitreoretinopathy (FEVR) using full-field electroretinography (ERG). Seventeen eyes of nine patients with FEVR who had Rdrag or Rfolds were retrospectively studied. Eyes were classified into four groups according to the severity of the retinal alterations: Group 1, without Rdrag or Rfolds (5 eyes); Group 2, with Rdrag (4 eyes); Group 3, with Rfolds (6 eyes); and Group 4, with Rfolds in which all major retinal vessels were involved (2 eyes). The amplitudes of all ERG components and the implicit times of the photopic a- and b-waves and 30-Hz flicker responses were decreased or prolonged as the severity of the retinal alterations increased (P < 0.01). The photopic negative response was most severely affected and nearly undetectable in all eyes in Groups 3 and 4, although the other ERG components were detectable in all eyes in Group 3 and one eye in Group 4. These results suggest the decrease of retinal functions was correlated with the degree of severity of Rdrag and Rfolds in eyes with FEVR. In addition, the function of the retinal ganglion cells appears to be more severely affected compared with the others.

Trisection technique for the extraction of dislocated intraocular lenses through a small surgical incision

&NA; We describe a trisection technique for extracting a dislocated IOL through a small surgical incision. The dislocated IOL is brought into the anterior chamber and cut into 3 equal segments, with a negligible risk for the segments falling into the vitreous cavity. Financial Disclosure No author has a financial or proprietary interest in any material or method mentioned.