Gene Augmentation for Autosomal Dominant CRX-Associated Retinopathies

Bifocal retinal degeneration observed on ultra-widefield autofluorescence in some cases of CRX-associated retinopathy

BACKGROUND

Variants in CRX are associated with dominantly inherited retinopathy with considerable phenotypic variability. Many patients have central retinal degeneration; in some patients, we have observed an additional focus of degeneration in the nasal retina. This study explores this phenotypic association amongst patients with CRX-associated disease.

METHODS

A retrospective review was conducted for all patients with dominant CRX-associated retinopathy at two UK centres. Analysis focused on patients with available ultra-widefield autofluorescence imaging and aimed to identify those with a specific bifocal degeneration pattern involving the nasal retina in both eyes.

RESULTS

Sixty patients were identified, with ultra-widefield fundus imaging available for 50 patients. Of these, six male patients aged 26-74 years displayed a distinct pattern characterised by central retinal degeneration and an additional discrete area of altered autofluorescence in the nasal periphery. Pattern and full-field ERGs indicated macular dysfunction in all 6 cases, with generalised cone (n = 2) or cone and rod (n = 4) system involvement, with a locus that appeared to be post-phototransduction. The CRX variants found in these patients included missense variants (n = 2), frameshifting variants (n = 3), and a CRX whole gene deletion (n = 1), with no clear genotype-phenotype correlation identified.

CONCLUSIONS

We report a distinct pattern of bifocal retinal degeneration in some cases of CRX-associated retinopathy (12% in our cohort), not typically seen in other forms of inherited retinal disease. Recognising such phenotypes can guide genetic investigations or their interpretation, facilitating molecular diagnoses for effective family counselling, given the autosomal dominant inheritance and phenotypic variability of CRX-associated retinopathy.

Perspectives of traditional herbal medicines in treating retinitis pigmentosa

Medicinal plants, also known as herbs, have been discovered and utilized in traditional medical practice since prehistoric times. Medicinal plants have been proven rich in thousands of natural products that hold great potential for the development of new drugs. Previously, we reviewed the types of Chinese traditional medicines that a Tang Dynasty monk Jianzhen (Japanese: Ganjin) brought to Japan from China in 742. This article aims to review the origin of Kampo (Japanese traditional medicine), and to present the overview of neurodegenerative diseases and retinitis pigmentosa as well as medicinal plants in some depth. Through the study of medical history of the origin of Kampo, we found that herbs medicines contain many neuroprotective ingredients. It provides us a new perspective on extracting neuroprotective components from herbs medicines to treat neurodegenerative diseases. Retinitis pigmentosa (one of the ophthalmic neurodegenerative diseases) is an incurable blinding disease and has become a popular research direction in global ophthalmology. To date, treatments for retinitis pigmentosa are very limited worldwide. Therefore, we intend to integrate the knowledge and skills from different disciplines, such as medical science, pharmaceutical science and plant science, to take a new therapeutic approach to treat neurodegenerative diseases. In the future, we will use specific active ingredients extracted from medicinal plants to treat retinitis pigmentosa. By exploring the potent bioactive ingredients present in medicinal plants, a valuable opportunity will be offered to uncover novel approaches for the development of drugs which target for retinitis pigmentosa.

Transcriptional precision in photoreceptor development and diseases - Lessons from 25 years of CRX research

The vertebrate retina is made up of six specialized neuronal cell types and one glia that are generated from a common retinal progenitor. The development of these distinct cell types is programmed by transcription factors that regulate the expression of specific genes essential for cell fate specification and differentiation. Because of the complex nature of transcriptional regulation, understanding transcription factor functions in development and disease is challenging. Research on the Cone-rod homeobox transcription factor CRX provides an excellent model to address these challenges. In this review, we reflect on 25 years of mammalian CRX research and discuss recent progress in elucidating the distinct pathogenic mechanisms of four CRX coding variant classes. We highlight how in vitro biochemical studies of CRX protein functions facilitate understanding CRX regulatory principles in animal models. We conclude with a brief discussion of the emerging systems biology approaches that could accelerate precision medicine for CRX-linked diseases and beyond.

The New Era of Therapeutic Strategies for the Treatment of Retinitis Pigmentosa: A Narrative Review of Pathomolecular Mechanisms for the Development of Cell-Based Therapies

Retinitis pigmentosa, defined more properly as cone-rod dystrophy, is a paradigm of inherited diffuse retinal dystrophies, one of the rare diseases with the highest prevalence in the worldwide population and one of the main causes of low vision in the pediatric and elderly age groups. Advancements in and the understanding of molecular biology and gene-editing technologies have raised interest in laying the foundation for new therapeutic strategies for rare diseases. As a consequence, new possibilities for clinicians and patients are arising due to the feasibility of treating such a devastating disorder, reducing its complications. The scope of this review focuses on the pathomolecular mechanisms underlying RP better to understand the prospects of its treatment using innovative approaches.