Panel-based genetic testing for inherited retinal disease screening 176 genes.

BACKGROUND: This case series reports the performance of a next-generation sequencing (NGS) panel of 176 retinal genes (NGS 176) in patients with inherited retinal disease (IRD). METHODS: Subjects are patients who underwent genetic testing between 1 August 2016 and 1 January 2018 at Moorfields Eye Hospital, London, UK. Panel-based genetic testing was performed unless a specific gene (e.g., RS1) or small group of genes (e.g., ABCA4, PRPH2) were suspected. If a novel variant was identified, a further comment on their predicted pathogenicity and evolutionary conservation was offered and segregation studies performed. The main outcome measure is the likelihood of obtaining a genetic diagnosis using NGS 176. RESULTS: 488 patients were included. A molecular diagnosis was obtained for 59.4% of patients. Younger patients were more likely to receive a molecular diagnosis; with 92% of children under the age of 6 years receiving a conclusive result. There was a change in their initially assigned inheritance pattern in 8.4% of patients following genetic testing. Selected IRD diagnoses (e.g., achromatopsia, congenital stationary night blindness) were associated with high diagnostic yields. CONCLUSION: This study confirms that NGS 176 is a useful first-tier genetic test for most IRD patients. Age and initial clinical diagnosis were strongly associated with diagnostic yield.

Peripheral pigmented lesions in ABCA4-associated retinopathy.

Purpose: To investigate the prevalence and characteristics of peripheral pigmented retinal lesions and the associated clinical and genetic findings in patients with pathogenic variants in the ABCA4 gene.Methods: Records at a single tertiary hospital were retrospectively reviewed to identify the presence of peripheral pigmented retinal lesions on wide-field retinal imaging in patients with ABCA4-associated disease, compared with an RDS/PRPH2 cohort, and an age-matched control group. Data on patient demographics, genetic variants, severity of disease, and phenotype were collected and assessed.Results: Of 91 patients with at least one pathogenic variant in the ABCA4 gene and fundal changes consistent with ABCA4 retinal dystrophy, 15 (16.5%) had peripheral pigmented retinal lesions in 20 eyes, and were bilateral in 6 patients. These flat, subretinal lesions were located in the mid- or far periphery, not involving the macula, and had well-defined borders. Most affected eyes had a solitary lesion (n = 18) with lesions more commonly present in the temporal half of the retina. Twenty-one unique genetic variants in ABCA4 were associated with these lesions. In 26 subjects (52 eyes) with RDS/PRPH-2-associated IRD, and in 30 age-matched controls (60 eyes), only one control eye had a pigmented lesion consistent with congenital hypertrophy of the retinal pigment epithelium and there were no peripheral pigmented lesions.Conclusions: Almost one-fifth of patients with ABCA4-associated retinopathy have peripheral pigmented retinal lesions. The presence of these lesions is associated with more severe disease with an earlier onset than in patients without the lesions, and is an aid to diagnosis.

Leber Congenital Amaurosis Associated with Mutations in CEP290, Clinical Phenotype, and Natural History in Preparation for Trials of Novel Therapies.

PURPOSE: To investigate and describe in detail the demographics, functional and anatomic characteristics, and clinical course of Leber congenital amaurosis (LCA) associated with mutations in the CEP290 gene (LCA-CEP290) in a large cohort of adults and children. DESIGN: Retrospective case series. PARTICIPANTS: Patients with mutations in CEP290 identified at a single UK referral center. METHODS: Review of case notes and results of retinal imaging (color fundus photography, fundus autofluorescence [FAF] imaging, OCT), electrophysiologic assessment, and molecular genetic testing. MAIN OUTCOME MEASURES: Molecular genetic testing, clinical findings including visual acuity and retinal imaging, and electrophysiologic assessment. RESULTS: Forty patients with LCA-CEP290 were identified. The deep intronic mutation c.2991+1655 A>G was the most common disease-causing variant (23/40 patients) identified in the compound heterozygous state in 20 patients (50%) and homozygous in 2 patients (5%). Visual acuity (VA) varied from 6/9 to no perception of light, and only 2 of 12 patients with longitudinal VA data showed deterioration in VA in their better-seeing eye over time. A normal fundus was found at diagnosis in younger patients (mean age, 1.9 years), with older patients showing white flecks (mean age, 5.9 years) or pigmentary retinopathy (mean age, 21.7 years). Eleven of 12 patients (92%) with OCT imaging had preservation of foveal architecture. Ten of 12 patients (83%) with FAF imaging had a perifoveal hyperautofluorescent ring. Having 2 nonsense CEP290 mutations was associated with worse final VA and the presence of nonocular features. CONCLUSIONS: Detailed analysis of the clinical phenotype of LCA-CEP290 in a large cohort confirms that there is a window of opportunity in childhood for therapeutic intervention based on relative structural preservation in the central cone-rich retina in a significant proportion of patients, with the majority harboring the deep intronic variant potentially tractable to several planned gene editing approaches.

Screening the visual system homeobox 1 gene in keratoconus and posterior polymorphous dystrophy cohorts identifies a novel variant.

PURPOSE: Mutations in the visual system homeobox 1 (VSX1) gene have been described at a low frequency in keratoconus and posterior polymorphous corneal dystrophy (PPCD). The putative role is controversial for several reasons, including a lack of mutations detected in other population cohorts. This study aims to determine whether VSX1 contributes to the genetic pathogenesis of keratoconus and PPCD in a New Zealand population, and includes analysis of a Polynesian population. METHODS: Recruitment of patients with keratoconus and PPCD, comprehensive clinical examination including corneal topography and pachymetry, and collection of biologic samples for DNA extraction were undertaken. Mutational analysis of VSX1 (exons 1-7) with PCR and sequencing with bioinformatic assessment of variants was performed. Probable pathogenic variants were screened for in a control population using high-resolution melting analysis. RESULTS: Forty-seven patients with keratoconus, including 15 familial cases, and ten unrelated patients with PPCD were recruited. Two pathogenic changes were detected; a novel change c.173C>T (p.Pro58Leu) was found in a patient with PPCD, predicted to be pathogenic, and not seen in 200 ethnically matched control alleles. The previously reported c.731A>G (p.His244Arg) was detected in a patient with sporadic keratoconus, and not present in the controls. No family members were available for segregation analysis. CONCLUSIONS: This study reports the presence of pathogenic mutations in VSX1 in PPCD and keratoconus, including a novel disease-causing variant. The affected numbers are small, but given the growing body of evidence of pathogenic segregating changes in VSX1 in disease cohorts, the expression in keratocytes as part of wound healing, and the documented association of PPCD and keratoconus, it seems likely that the role of VSX1 as a genetic factor contributing to disease is real.

Clinical findings and molecular diagnosis of retinoblastoma in older children.

BACKGROUND: Retinoblastoma (RB) is the most common primary childhood intraocular malignancy and usually presents before the age of 4 years. RB in late childhood is rare and may pose a diagnostic challenge to clinicians. MATERIALS AND METHODS: Patients over the age of 4 years with RB were identified retrospectively. Clinical data, histological findings, and molecular genetic diagnoses were obtained. RESULTS: Two cases of late onset RB were identified. Case 1 was a 10-year-old boy who presented with floaters, and was found to have a unilateral exudative retinal detachment and RB on clinical examination. Genetic testing showed a novel homozygous mutation in exon 20 of the RB1 gene in the tumor sample, c.2027_2034dup, resulting in p.Ile679X. No mutation was found in the DNA obtained from the peripheral blood sample. Case 2 was a 6-year-old boy who presented with loss of vision and pain in the left eye. RB was diagnosed on clinical examination with exudative retinal detachment. Genetic testing showed no mutation in the RB1 gene, but complete methylation of the RB1 promoter region. CONCLUSIONS: RB can rarely present in late childhood. Clinicians should consider RB as a diagnosis when faced with a patient with unexplained exudative retinal detachment.

Analysis of the pre-retinal opacities in Gaucher Disease using spectral domain optical coherent tomography.

Fundal opacities have been reported in patients with Gaucher disease, a rare autosomal recessive lysosomal storage disease, prior to the advent of optical coherent tomography. This report provides a detailed analysis of the fundal opacities in a 14-year-old girl with genetically proven Gaucher disease using spectral domain optical coherent tomography. It illustrates clearly that these opacities were pre-retinal opacities located at the vitreo-retinal interface associated with localized posterior vitreous detachments, rather than vitreous opacities as previously suggested in the literature.

Impaired complex-I-linked respiration and ATP synthesis in primary open-angle glaucoma patient lymphoblasts.

PURPOSE: Following the recent demonstration of increased mitochondrial DNA mutations in lymphocytes of POAG patients, the authors sought to characterize mitochondrial function in a separate cohort of POAG. METHODS: Using similar methodology to that previous applied to Leber's hereditary optic neuropathy (LHON) patients, maximal adenosine triphosphate (ATP) synthesis and cellular respiration rates, as well as cell growth rates in glucose and galactose media, were assessed in transformed lymphocytes from POAG patients (n = 15) and a group of age- and sex-matched controls (n = 15). RESULTS: POAG lymphoblasts had significantly lower rates of complex-I-driven ATP synthesis, with preserved complex-II-driven ATP synthesis. Complex-I driven maximal respiration was also significantly decreased in patient cells. Growth in galactose media, where cells are forced to rely on mitochondrial ATP production, revealed no significant differences between the control and POAG cohort. CONCLUSIONS: POAG lymphoblasts in the study cohort exhibited a defect in complex-I of the oxidative phosphorylation pathway, leading to decreased rates of respiration and ATP production. Studies in LHON and other diseases have established that lymphocyte oxidative phosphorylation measurement is a reliable indicator of systemic dysfunction of this pathway. While these defects did not impact lymphoblast growth when the cells were forced to rely on oxidative ATP supply, the authors suggest that in the presence of a multitude of cellular stressors as seen in the early stages of POAG, these defects may lead to a bioenergetic crisis in retinal ganglion cells and an increased susceptibility to cell death.

Alström syndrome--an uncommon cause of early childhood retinal dystrophy.

Alström syndrome (AS) is a ciliopathy and an uncommon cause of syndromic retinal dystrophy. This case reports findings in a 5-year-old boy with severe early onset retinal dystrophy, and how the recognition of extraocular features with genetic analysis led to the correct diagnosis of AS after 4 years of investigation.

Selenium and ocular health in New Zealand.

Selenium is an essential mineral and severe selenium deficiency is known to cause significant health problems. It has been well documented that New Zealand soil is low in selenium. Recent studies have addressed the roles of selenoproteins in the eyes, with evidence suggesting that selenium supplementation may have a role in preventing cataract formation and age-related maculopathy. This paper summarises the role of selenium in ocular and general health and discusses selenium supplementation in a New Zealand specific context.