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Gene Therapy for Retina and Eye Diseases
Published in Yashwant V. Pathak, Gene Delivery Systems, 2022
AAV vectors have limited capacity, which restricts the packaging of large transgenes (16). To overcome the capacity issue, a dual AAV8 vector was used in patients with Usher syndrome 1B (USHIB) to target the myosin 7A (MYO7A) gene. This gene therapy was designated as an orphan drug by the European Medicines Agency (EMA) (17–18). The efficacy was limited due to lower protein expression as compared to a single AAV vector (19–20).
Induced Pluripotent Stem Cells: A Research Tool and a Potential Therapy for RPE-Associated Blinding Eye Diseases
Published in Deepak A. Lamba, Patient-Specific Stem Cells, 2017
Ruchi Sharma, Balendu Shekhar Jha, Kapil Bharti
Retinitis pigmentosa (RP) is a hereditary retinal dystrophy that starts as a rod photoreceptor degeneration disease, leading to night blindness but also progressively leads to central vision loss in these patients (van Soest et al., 1999; Hartong et al., 2006). It is a rare genetic disorder with a worldwide prevalence of 1 in 4000 individuals. Its inheritance pattern is quite heterogeneous and can be caused by autosomal or X-linked mutations and can be dominant or recessive (Rivolta et al., 2002). More than 60 gene mutations are known to cause RP, which can be syndromic or nonsyndromic in phenotype (Hartong et al., 2006). Most of these genes can be categorized into subfamilies depending upon their known function in the eye or in other organs. Within the eye, there are three categories of genes whose mutations lead to RP (Hartong et al., 2006): (a) gene mutations that directly affect photoreceptor function and survival (e.g., rhodopsin, phosphodiesterase 6A [PDE6A], PDE6B, cyclic nucleotide gated channel alpha 1 [CNGA1], CNGB1, S-antigen visual arrestin, peripherin 2, retinal outer segment membrane protein 1, fascin actin-bundling protein 2, tubby-like protein 1, crumbs 1, retinitis pigmentosa 1 [RP1]); (b) gene mutations that lead to syndromic phenotype and may affect both RPE and photoreceptors (e.g., usher syndrome 1 protein network component [USH1C], Usher syndrome type 2A [USH2A], USH3A, pre-mRNA processing factor 31 [PRPF31], PRPF8, PRPF3, RP9, Bardet–Biedl syndrome 1 [BBS1], BBS2, adenosine diphosphate ribosylation factor-like GTPase 6 [ARL6], BBS4, BBS5, McKusick–Kaufman syndrome [MKKS], BBS7, tetratricopeptide repeat domain 8 [TTC8], parathyroid hormone responsive B1, retinitis pigmentosa GTPase regulator); and (c) gene mutations that predominantly affect RPE function but also lead to photoreceptor cell death (e.g., membrane-frizzled-related protein [MFRP], RPE65, retinaldehyde-binding protein 1 [RLBP1], lecithin retinol acyltransferase [LRAT], myosin 7a, carbonic anhydrase 4 [CA4], MERTK). Here, we focus primarily on genes that either specifically affect RPE function or are syndromic in nature and affect both RPE and photoreceptors.
Horseback riding therapy for a deafblind individual enabled by a haptic interface
Published in Assistive Technology, 2018
Matjaž Ogrinc, Ildar Farkhatdinov, Rich Walker, Etienne Burdet
Depending on the age of onset sensory loss, deafblindness can be congenital or acquired. In the case of the former, the impairment occurs before age of two and is also known as prelingual deafblindness. Only around one in five cases of deafblindess is congenital. The common causes are CHARGE syndrome and prematurity (Dammeyer, 2012). On the other hand, the most common cause of acquired deafblindness is an extremely rare genetic disorder known as Usher syndrome. This is the case in approximately half of the people with the impairment—excluding the cases related to aging (Moller, 2003). An accurate identification of congenital impairment is difficult as it requires cooperation of the examined person at a very young age, who may also be affected by severe motor, cognitive, and behavioral impairments.