Patients and animal models of CNGβ1-deficient retinitis pigmentosa support gene augmentation approach.

Retinitis pigmentosa (RP) is a major cause of blindness that affects 1.5 million people worldwide. Mutations in cyclic nucleotide-gated channel β 1 (CNGB1) cause approximately 4% of autosomal recessive RP. Gene augmentation therapy shows promise for treating inherited retinal degenerations; however, relevant animal models and biomarkers of progression in patients with RP are needed to assess therapeutic outcomes. Here, we evaluated RP patients with CNGB1 mutations for potential biomarkers of progression and compared human phenotypes with those of mouse and dog models of the disease. Additionally, we used gene augmentation therapy in a CNGβ1-deficient dog model to evaluate potential translation to patients. CNGB1-deficient RP patients and mouse and dog models had a similar phenotype characterized by early loss of rod function and slow rod photoreceptor loss with a secondary decline in cone function. Advanced imaging showed promise for evaluating RP progression in human patients, and gene augmentation using adeno-associated virus vectors robustly sustained the rescue of rod function and preserved retinal structure in the dog model. Together, our results reveal an early loss of rod function in CNGB1-deficient patients and a wide window for therapeutic intervention. Moreover, the identification of potential biomarkers of outcome measures, availability of relevant animal models, and robust functional rescue from gene augmentation therapy support future work to move CNGB1-RP therapies toward clinical trials

Spectrum of PEX1 and PEX6 variants in Heimler syndrome

Heimler syndrome (HS) consists of recessively inherited sensorineural hearing loss, amelogenesis imperfecta (AI) and nail abnormalities, with or without visual defects. Recently HS was shown to result from hypomorphic mutations in PEX1 or PEX6, both previously implicated in Zellweger Syndrome Spectrum Disorders (ZSSD). ZSSD are a group of conditions consisting of craniofacial and neurological abnormalities, sensory defects and multi-organ dysfunction. The finding of HS-causing mutations in PEX1 and PEX6 shows that HS represents the mild end of the ZSSD spectrum, though these conditions were previously thought to be distinct nosological entities. Here, we present six further HS families, five with PEX6 variants and one with PEX1 variants, and show the patterns of Pex1, Pex14 and Pex6 immunoreactivity in the mouse retina. While Ratbi et al. found more HS-causing mutations in PEX1 than in PEX6, as is the case for ZSSD, in this cohort PEX6 variants predominate, suggesting both genes play a significant role in HS. The PEX6 variant c.1802G>A, p.(R601Q), reported previously in compound heterozygous state in one HS and three ZSSD cases, was found in compound heterozygous state in three HS families. Haplotype analysis suggests a common founder variant. All families segregated at least one missense variant, consistent with the hypothesis that HS results from genotypes including milder hypomorphic alleles. The clinical overlap of HS with the more common Usher syndrome and lack of peroxisomal abnormalities on plasma screening suggest that HS may be under-diagnosed. Recognition of AI is key to the accurate diagnosis of HS

Patients and animal models of CNG beta 1-deficient retinitis pigmentosa support gene augmentation approach

Retinitis pigmentosa (RP) is a major cause of blindness that affects 1.5 million people worldwide. Mutations in cyclic nucleotide-gated channel beta 1 (CNGB1) cause approximately 4% of autosomal recessive RP. Gene augmentation therapy shows promise for treating inherited retinal degenerations;however, relevant animal models and biomarkers of progression in patients with RP are needed to assess therapeutic outcomes. Here, we evaluated RP patients with CNGB1 mutations for potential biomarkers of progression and compared human phenotypes with those of mouse and dog models of the disease. Additionally, we used gene augmentation therapy in a CNG beta 1-deficient dog model to evaluate potential translation to patients. CNGB1-deficient RP patients and mouse and dog models had a similar phenotype characterized by early loss of rod function and slow rod photoreceptor loss with a secondary decline in cone function. Advanced imaging showed promise for evaluating RP progression in human patients, and gene augmentation using adeno-associated virus vectors robustly sustained the rescue of rod function and preserved retinal structure in the dog model. Together, our results reveal an early loss of rod function in CNGB1-deficient patients and a wide window for therapeutic intervention. Moreover, the identification of potential biomarkers of outcome measures, availability of relevant animal models, and robust functional rescue from gene augmentation therapy support future work to move CNGB1-RP therapies toward clinical trials

Handbook of ocular genetics

Includes bibliographical references and index"Many serious, potentially blinding eye disorders have a genetic basis. Currently, there are relatively few ocular geneticists in the world, yet inherited eye disease is one of the leading causes of blindness worldwide. Significant strides have been made in gene identification and acquisition of knowledge on the underlying mechanisms of hereditary eye disease. The field of ocular genetics is becoming an increasingly relevant part of ophthalmologists'purview. This has resulted in a dire need for a comprehensive textbook ophthalmologists and other professionals who work with patients with genetic disorders can utilize to gain a better understanding of inherited eye disorders.The Wills Eye Handbook of Ocular Genetics, by Alex Levin, Mario Zanolli, and Jenina Capasso of Wills Eye Hospital, is a practical, reader-friendly guide on the diagnosis and management of ophthalmic genetic conditions. Every chapter begins with a disease overview, followed by relevant modern genetic concepts, pathways to attaining the correct diagnosis, and pitfalls and pearls gleaned from years of hands-on expertise. At the end of each chapter, questions and answers enable readers to test their knowledge in real-life scenarios they might face in everyday practice. The ultimate goal of this clinically robust handbook is to facilitate optimal patient management and outcomes.Key FeaturesFundamentals, including basic genetics, inheritance patterns, genetic testing, and ethical issuesPatient-centered genetic counseling issues such as reproduction, dealing with emotional reactions, prognosis, and future optionsAnterior segment disorders - from corneal dystrophies and aniridia - to childhood cataract and microphthalmiaA broad spectrum of vitreoretinopathies and retinal diseases including incontinentia pigmenti, retinitis pigmentosa, Bardet-Biedl syndrome, choroideremia, Stargardt disease, achromatopsia, and juvenile X-linked retinoschisisThis textbook is essential reading for practitioners at all levels and in all subspecialties including ophthalmology and genetics. They will find it an excellent resource for navigating the complexities of genetic eye disease."--Publisher.Basic Genetics -- Inheritance Patterns -- Genetic Testing -- Ethical Issues -- Corneal Dystrophies - Aniridia -- Peters Anomaly -- Axenfeld-Rieger Syndrome -- Primary Congenital Glaucoma and Juvenile Open Angle Glaucoma -- Childhood Cataract - Microphthalmia -- Marfan Syndrome and Other Causes of Ectopia Lentis -- Familial Exudative Vitreoretinopathy -- Stickler Syndrome -- VCAN Vitreoretinopathies (Erosive Vitreoretinopathy and Wagner Syndrome) -- Incontinentia Pigmenti -- Retinitis Pigmentosa -- Usher Syndrome -- Bardet-Biedl Syndrome -- Cone-Rod Dystrophy - Choroideremia -- Enhanced S-Cone Syndrome and Other NR2E3-Related Retinal Dystrophies -- Stargardt Disease and Other ABCA4 Retinopathies -- Best Vitelliform Macular Dystrophy (Best Disease) -- Leber Congenital Amaurosis - Achromatopsia -- Congenital Stationary Night Blindness -- Juvenile X-Linked Retinoschisis - Retinoblastoma -- Optic Nerve Hypoplasia -- Leber Hereditary Optic Neuropathy -- Complex Ocular Disorders - Albinism.1 online resource

Genetics for the ophthalmologist.

The eye has played a major role in human genomics including gene therapy. It is the fourth most common organ system after integument (skin, hair and nails), nervous system, and musculoskeletal system to be involved in genetic disorders. The eye is involved in single gene disorders and those caused by multifactorial etiology. Retinoblastoma was the first human cancer gene to be cloned. Leber hereditary optic neuropathy was the first mitochondrial disorder described. X-Linked red-green color deficiency was the first X-linked disorder described. The eye, unlike any other body organ, allows directly visualization of genetic phenomena such as skewed X-inactivation in the fundus of a female carrier of ocular albinism. Basic concepts of genetics and their application to clinical ophthalmological practice are important not only in making a precise diagnosis and appropriate referral, but also in management and genetic counseling

Genetics of the anterior segment dysgenesis

The anterior segment dysgeneses are a broad group of heterogeneous disorders characterized by developmental abnormalities of the anterior segment of the eye, including primary congenital aphakia, Peters sequence, aniridia, and Axenfeld–Rieger spectrum. These conditions can have overlapping phenotypes and both genotypic and phenotypic heterogeneity. This article provides a strategy for both phenotyping and then genotyping using a targeted stepwise approach

How genetics works? An illustrative case report.

In this communication, we report the case of a four year old boy who presented with reduced vision in the right eye. He had visual acuity of light perception right eye and 6/12 in the left eye and anterior segment examination was normal. Fundus examination of the right eye showed a falciform retinal fold extending from the optic nerve temporally involving the entire retina with exudates within the falciform fold and dense pigmentation peripherally. The left eye showed mild macular temporal dragging of the vessels and 360° of peripheral laser scars. In addition he also had some characteristic systemic features such as developmental delay, obesity, dysmorphic facies and tapered fingers. Using this case as an example, we present a systematic, logical approach to a patient with a possible genetic disorder. The growing field of ocular genetics now allows for improved diagnosis using step-wise cost efficient testing as demonstrated herein

Organophosphate retinopathy

Organophosphates have rarely been reported to cause various ocular sequelae including retinal degeneration. Retinal manifestations have been rarely reported and poorly characterized. We describe a case of a 76-year-old man with vision loss beginning in his 20s due to acute on chronic exposure to dimethoate, an organophosphate. He presented with bilateral geographic macular atrophy and midperipheral pigmentary clumping which we characterized by dilated fundoscopic examination, optical coherence tomography, and fundus autofluorescence

Novel CRB1 pathogenic variant in Chuuk families with Leber congenital amaurosis.

The purpose of this article is to determine the cause of Leber congenital amaurosis (LCA) in Chuuk state, Federated States of Micronesia (FSM). In this prospective observational case series, five patients with early-onset vision loss were examined in Chuuk state, FSM, during an ocular genetics visit to study the elevated incidence of microphthalmia. Because of their low vision these patients were incorrectly assumed to have microphthalmia. A complete ophthalmological exam established a clinical diagnosis of LCA. Candidate gene exons were sequenced with a targeted retinal dystrophy panel. Five subjects in three related families were diagnosed with LCA. All five were from Tonoas Island, within the Chuuk Lagoon, with ages ranging from 6 months to 16 years. DNA sequencing of affected individuals revealed a homozygous CRB1 NM_201253.3:c.3134del pathogenic variant, which was heterozygous in their parents. CRB1 genotypes were confirmed by a PCR restriction assay. We report identification of a founder pathogenic variant in CRB1 responsible for autosomal recessive LCA in this isolated community. This discovery will lead to appropriate recurrence risk counseling