Diagnostic exome sequencing in 266 Dutch patients with visual impairment

Inherited eye disorders have a large clinical and genetic heterogeneity, which makes genetic diagnosis cumbersome. An exome-sequencing approach was developed in which data analysis was divided into two steps: the vision gene panel and exome analysis. In the vision gene panel analysis, variants in genes known to cause inherited eye disorders were assessed for pathogenicity. If no causative variants were detected and when the patient consented, the entire exome data was analyzed. A total of 266 Dutch patients with different types of inherited eye disorders, including inherited retinal dystrophies, cataract, developmental eye disorders and optic atrophy, were investigated. In the vision gene panel analysis (likely), causative variants were detected in 49% and in the exome analysis in an additional 2% of the patients. The highest detection rate of (likely) causative variants was in patients with inherited retinal dystrophies, for instance a yield of 63% in patients with retinitis pigmentosa. In patients with developmental eye defects, cataract and optic atrophy, the detection rate was 50, 33 and 17%, respectively. An exome-sequencing approach enables a genetic diagnosis in patients with different types of inherited eye disorders using one test. The exome approach has the same detection rate as targeted panel sequencing tests, but offers a number of advantages. For instance, the vision gene panel can be frequently and easily updated with additional (novel) eye disorder genes. Determination of the genetic diagnosis improved the clinical diagnosis, regarding the assessment of the inheritance pattern as well as future disease perspective

Diagnostic exome sequencing in 266 Dutch patients with visual impairment

Inherited eye disorders have a large clinical and genetic heterogeneity, which makes genetic diagnosis cumbersome. An exome-sequencing approach was developed in which data analysis was divided into two steps: the vision gene panel and exome analysis. In the vision gene panel analysis, variants in genes known to cause inherited eye disorders were assessed for pathogenicity. If no causative variants were detected and when the patient consented, the entire exome data was analyzed. A total of 266 Dutch patients with different types of inherited eye disorders, including inherited retinal dystrophies, cataract, developmental eye disorders and optic atrophy, were investigated. In the vision gene panel analysis (likely), causative variants were detected in 49% and in the exome analysis in an additional 2% of the patients. The highest detection rate of (likely) causative variants was in patients with inherited retinal dystrophies, for instance a yield of 63% in patients with retinitis pigmentosa. In patients with developmental eye defects, cataract and optic atrophy, the detection rate was 50, 33 and 17%, respectively. An exome-sequencing approach enables a genetic diagnosis in patients with different types of inherited eye disorders using one test. The exome approach has the same detection rate as targeted panel sequencing tests, but offers a number of advantages. For instance, the vision gene panel can be frequently and easily updated with additional (novel) eye disorder genes. Determination of the genetic diagnosis improved the clinical diagnosis, regarding the assessment of the inheritance pattern as well as future disease perspective

Evaluation of the visual pathway with ERG, mfERG and mfVEP in inherited eye disorders

This thesis will describe the clinical phenotypes, with emphasis on electrophysiology, in patients with different hereditary eye diseases and to further evaluate and modify the mfVEP technique for clinical use. Bothnia Dystrophy is a tapetoretinal disorder with a mutation in the RLBP1 gene. Early in the disease the fundus may have a normal appearance. The full-field ERG demonstrates an absence of the rod response but normal amplitudes for the cones. However, after prolonged dark adaptation the rods recover completely. MfERG can be used for objective documentation of the disturbed macular function. Patients with retinitis pigmentosa may not always follow the typical natural course of the disorder with progressive loss of the central visual fields, which may in some patients remain unaffected for several decades. MfERG and mfVEP may be of clinical use in evaluating remaining visual function in these patients. Patients with dominant optic atrophy and a known mutation in the OPA-1 gene have a very variable clinical phenotype. MfVEP and ocular blood flow measurements are two new methods for improved identification and characterization of this disorder. A patient with a known mutation for Leber`s hereditary optic neuropathy (LHON) was followed during the acute stage of the disease with mfVEP, demonstrating a correlation to the progression of the disease. The mfVEP may be of clinical value as an objective method for monitoring the course of this disease. MfVEP demonstrates the cortical response corresponding to the central visual field. An improvement for the clinical value of the method was the use of an IR-camera for both stimulation and for controlling the fixation. By introducing a two channel system it was possible to describe the uncrossed/crossed visual pathways and analyze inter-ocular differences

Clinical utility of genetic testing in 201 preschool children with inherited eye disorders

From Springer Nature via Jisc Publications RouterHistory: received 2019-09-23, registration 2019-11-25, accepted 2019-11-25, pub-electronic 2019-12-18, online 2019-12-18, pub-print 2020-04-01Publication status: PublishedAbstract: Purpose: A key property to consider in all genetic tests is clinical utility, the ability of the test to influence patient management and health outcomes. Here we assess the current clinical utility of genetic testing in diverse pediatric inherited eye disorders (IEDs). Methods: Two hundred one unrelated children (0–5 years old) with IEDs were ascertained through the database of the North West Genomic Laboratory Hub, Manchester, UK. The cohort was collected over a 7-year period (2011–2018) and included 74 children with bilateral cataracts, 8 with bilateral ectopia lentis, 28 with bilateral anterior segment dysgenesis, 32 with albinism, and 59 with inherited retinal disorders. All participants underwent panel-based genetic testing. Results: The diagnostic yield of genetic testing for the cohort was 64% (ranging from 39% to 91% depending on the condition). The test result led to altered management (including preventing additional investigations or resulting in the introduction of personalized surveillance measures) in 33% of probands (75% for ectopia lentis, 50% for cataracts, 33% for inherited retinal disorders, 7% for anterior segment dysgenesis, 3% for albinism). Conclusion: Genetic testing helped identify an etiological diagnosis in the majority of preschool children with IEDs. This prevented additional unnecessary testing and provided the opportunity for anticipatory guidance in significant subsets of patients

Genetic heterogeneity in autosomal dominant pattern dystrophy of the retina

PURPOSE: Mutations in the retinal degeneration slow (RDS)/peripherin gene have been shown to be associated with pattern dystrophy of the retina (PDR) and other retinal dystrophies. The aim of our study was to confirm or exclude the RDS locus and the rhodopsin (RHO) locus as the disease causing locus in a large Swiss family affected with pattern dystrophy of the retina. MATERIALS AND METHODS: A Swiss family with 14 members across 3 generations affected with PDR was examined. Eleven living family members were investigated using 6 markers surrounding the RDS and RHO loci. RESULTS: Linkage to two possible candidate genes, the RDS gene on chromosome 6p and the rhodopsin gene on chromosome 3q, could be excluded. CONCLUSIONS: The family provides evidence for genetic heterogeneity of PDR and is in agreement with heterogeneity in other retinal dystrophies. Further investigations are in progress to map the gene causing PDR in this family

Acceptability of Telegenetics for Families with Genetic Eye Diseases

Healthcare providers around the world have implemented remote routine consultations to minimise disruption during the COVID-19 pandemic. Virtual clinics are particularly suitable for patients with genetic eye diseases as they rely on detailed histories with genetic counselling. During April–June 2019, the opinion of carers of children with inherited eye disorders attending the ocular genetics service at Moorfields Eye Hospital NHS Foundation Trust (MEH) were canvassed. Sixty-five percent of families (n = 35/54) preferred to have investigations carried out locally rather than travel to MEH, with 64% opting for a virtual consultation to interpret the results. The most popular mode of remote contact was via telephone (14/31), with video call being least preferred (8/31). Hence, 54 families who had received a telephone consultation mid-pandemic (November 2020–January 2021) were contacted to re-evaluate the acceptability of telegenetics using the Clinical Genetics Satisfaction Indicator and Telemedicine Satisfaction Questionnaire. Overall, 50 carers participated (response rate 93%); 58% of participants found teleconsultations acceptable and 54% agreed they increased their access to care, but 67.5% preferred to be seen in person. Patient satisfaction was high with 90% strongly agreeing/agreeing they shared and received all necessary information. Ocular genetics is well-suited for remote service delivery, ideally alternated with face-to-face consultations