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Title: Development of gene therapy for achromatopsia due to CNGA3 mutations
Author: Matsuki, Takaaki
ISNI:       0000 0004 8500 3912
Awarding Body: UCL (University College London)
Current Institution: University College London (University of London)
Date of Award: 2019
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Achromatopsia is an autosomal recessive retinal degenerative disease affecting 1 in 30,000 to 50,000 people for Caucasians, and its main symptoms are loss of daylight vision, colour blindness from birth, pendular nystagmus and photophobia. Mutations in the cone-specific cyclic nucleotide-gated alpha 3 (CNGA3) gene account for 1 in 4 patients with achromatopsia in Europe. This thesis describes the development of a gene therapy for the treatment of achromatopsia due to mutations in CNGA3. Since achromatopsia is a relatively stationary condition and retinal structure is relatively well preserved even in adults, the condition presents a long treatment-window and may thus be particularly amenable to gene therapy. To minimise off target expression of a transgene, development of an efficient cone photoreceptor cell-specific promoter was essential. Six novel green opsin promoter and three new GNB3 promoter constructs were evaluated in cultured human embryonic stem cell derived retinal organoids and the promoter that provided the strongest cone specific expression in all cone subtypes was selected. This promoter was used in combination with a codon-optimised human CNGA3 and AAV8 capsid to rescue a murine model of achromatopsia. To evaluate time window for gene therapy in the murine model, gene therapy at up to 12 months was conducted. Improvement of retinal sensitivity as determined by full-field electroretinography was seen at all ages, but gene therapy at up to 1 month of age showed more efficacy compared with that performed at the later age. However, superior retinal explants, where cone photoreceptor degeneration is relatively slow, from mice treated at 6 months of age showed similar sensitivity to wild type retina as determined by multielectrode array. Histological analysis of retinal connectivity demonstrated that the connectivity was relatively preserved at advanced stage and post-synaptic markers were restored following gene therapy up to treatment at 12 months of age.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available