-
Survey of Ophthalmology 2023Congenital aniridia is a panocular disorder that is typically characterized by iris hypoplasia and aniridia-associated keratopathy (AAK). AAK results in the progressive... (Review)
Review
Congenital aniridia is a panocular disorder that is typically characterized by iris hypoplasia and aniridia-associated keratopathy (AAK). AAK results in the progressive loss of corneal transparency and thereby loss of vision. Currently, there is no approved therapy to delay or prevent its progression, and clinical management is challenging because of phenotypic variability and high risk of complications after interventions; however, new insights into the molecular pathogenesis of AAK may help improve its management. Here, we review the current understanding about the pathogenesis and management of AAK. We highlight the biological mechanisms involved in AAK development with the aim to develop future treatment options, including surgical, pharmacological, cell therapies, and gene therapies.
Topics: Humans; Corneal Diseases; Aniridia; Cornea; Vision Disorders; Forecasting
PubMed: 37146692
DOI: 10.1016/j.survophthal.2023.04.003 -
Taiwan Journal of Ophthalmology 2023The anterior segment dysgeneses are a broad group of heterogeneous disorders characterized by developmental abnormalities of the anterior segment of the eye, including... (Review)
Review
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.
PubMed: 38249510
DOI: 10.4103/tjo.TJO-D-23-00062 -
Progress in Retinal and Eye Research Jul 2023Congenital PAX6-aniridia, initially characterized by the absence of the iris, has progressively been shown to be associated with other developmental ocular abnormalities... (Review)
Review
Congenital PAX6-aniridia, initially characterized by the absence of the iris, has progressively been shown to be associated with other developmental ocular abnormalities and systemic features making congenital aniridia a complex syndromic disorder rather than a simple isolated disease of the iris. Moreover, foveal hypoplasia is now recognized as a more frequent feature than complete iris hypoplasia and a major visual prognosis determinant, reversing the classical clinical picture of this disease. Conversely, iris malformation is also a feature of various anterior segment dysgenesis disorders caused by PAX6-related developmental genes, adding a level of genetic complexity for accurate molecular diagnosis of aniridia. Therefore, the clinical recognition and differential genetic diagnosis of PAX6-related aniridia has been revealed to be much more challenging than initially thought, and still remains under-investigated. Here, we update specific clinical features of aniridia, with emphasis on their genotype correlations, as well as provide new knowledge regarding the PAX6 gene and its mutational spectrum, and highlight the beneficial utility of clinically implementing targeted Next-Generation Sequencing combined with Whole-Genome Sequencing to increase the genetic diagnostic yield of aniridia. We also present new molecular mechanisms underlying aniridia and aniridia-like phenotypes. Finally, we discuss the appropriate medical and surgical management of aniridic eyes, as well as innovative therapeutic options. Altogether, these combined clinical-genetic approaches will help to accelerate time to diagnosis, provide better determination of the disease prognosis and management, and confirm eligibility for future clinical trials or genetic-specific therapies.
Topics: Humans; PAX6 Transcription Factor; Aniridia; Eye Abnormalities; Mutation; Phenotype; Eye Proteins
PubMed: 36280537
DOI: 10.1016/j.preteyeres.2022.101133 -
The Ocular Surface Jul 2023The ocular surface, comprised of the corneal and conjunctival epithelium, innervation system, immune components, and tear-film apparatus, plays a key role in ocular... (Review)
Review
The ocular surface, comprised of the corneal and conjunctival epithelium, innervation system, immune components, and tear-film apparatus, plays a key role in ocular integrity as well as comfort and vision. Gene defects may result in congenital ocular or systemic disorders with prominent ocular surface involvement. Examples include epithelial corneal dystrophies, aniridia, ectrodactyly-ectodermal dysplasia-clefting (EEC) syndrome, xeroderma pigmentosum (XP), and hereditary sensory and autonomic neuropathy. In addition, genetic factors may interact with environmental risk factors in the development of several multifactorial ocular surface disorders (OSDs) such as autoimmune disorders, allergies, neoplasms, and dry eye disease. Advanced gene-based technologies have already been introduced in disease modelling and proof-of-concept gene therapies for monogenic OSDs. For instance, patient-derived induced pluripotent stem cells have been used for modelling aniridia-associated keratopathy (AAK), XP, and EEC syndrome. Moreover, CRISPR/Cas9 genome editing has been used for disease modelling and/or gene therapy for AAK and Meesmann's epithelial corneal dystrophy. A better understanding of the role of genetic factors in OSDs may be helpful in designing personalized disease models and treatment approaches. Gene-based approaches in monogenic OSDs and genetic predisposition to multifactorial OSDs such as immune-mediated disorders and neoplasms with known or possible genetic risk factors has been seldom reviewed. In this narrative review, we discuss the role of genetic factors in monogenic and multifactorial OSDs and potential opportunities for gene therapy.
Topics: Humans; Genetic Predisposition to Disease; Corneal Diseases; Cornea; Aniridia
PubMed: 37192706
DOI: 10.1016/j.jtos.2023.05.003 -
Molecular Therapy. Nucleic Acids Sep 2023Congenital aniridia is a rare, pan-ocular disease causing severe sight loss, with only symptomatic intervention offered to patients. Approximately 40% of aniridia...
Congenital aniridia is a rare, pan-ocular disease causing severe sight loss, with only symptomatic intervention offered to patients. Approximately 40% of aniridia patients present with heterozygous nonsense variants in , resulting in haploinsufficiency. Translational readthrough-inducing drugs (TRIDs) have the ability to weaken the recognition of in-frame premature termination codons (PTCs), permitting full-length protein to be translated. We established induced pluripotent stem cell (iPSC)-derived 3D optic cups and 2D limbal epithelial stem cell (LESC) models from two aniridia patients with prevalent nonsense mutations. Both models show reduced PAX6 protein levels, mimicking the disease. The repurposed TRIDs amlexanox and 2,6-diaminopurine (DAP) and the positive control compounds ataluren and G418 were tested for their efficiency. Amlexanox was identified as the most promising TRID, increasing full-length PAX6 levels in both models and rescuing the disease phenotype through normalization of VSX2 and cell proliferation in the optic cups and reduction of ABCG2 protein and expression in LESCs. This study highlights the significance of patient iPSC-derived cells as a new model system for aniridia and proposes amlexanox as a new putative treatment for nonsense-mediated aniridia.
PubMed: 37483273
DOI: 10.1016/j.omtn.2023.06.016