Leber Hereditary Optic Neuropathy: Molecular Pathophysiology and Updates on Gene Therapy.
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ABSTRACT:
SUBMITTER: Chi SC
PROVIDER: S-EPMC9405679 | biostudies-literature | 2022 Aug
REPOSITORIES: biostudies-literature
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Leber Hereditary Optic Neuropathy: Molecular Pathophysiology and Updates on Gene Therapy.
Chi Sheng-Chu SC Cheng Hui-Chen HC Wang An-Guor AG
Biomedicines 20220809 8
Molecular pathophysiology of LHON was reviewed and the current status of gene therapy for LHON is updated. ...[more]
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Project description:PurposeLeber hereditary optic neuropathy (LHON) is a disorder characterized by severe and rapidly progressive visual loss when caused by a mutation in the mitochondrial gene encoding NADH:ubiquinone oxidoreductase subunit 4 (ND4). We have initiated a gene therapy trial to determine the safety and tolerability of escalated doses of an adeno-associated virus vector (AAV) expressing a normal ND4 complementary DNA in patients with a G to A mutation at nucleotide 11778 of the mitochondrial genome.DesignIn this prospective open-label trial (NCT02161380), the study drug (self-complementary AAV [scAAV]2(Y444,500,730F)-P1ND4v2) was intravitreally injected unilaterally into the eyes of 5 blind participants with G11778A LHON. Four participants with visual loss for more than 12 months were treated. The fifth participant had visual loss for less than 12 months. The first 3 participants were treated at the low dose of vector (5 × 10(9) vg), and the fourth participant was treated at the medium dose (2.46 × 10(10) vg). The fifth participant with visual loss for less than 12 months received the low dose. Treated participants were followed for 90 to 180 days and underwent ocular and systemic safety assessments along with visual structure and function examinations.ParticipantsFive legally blind patients with G11778A LHON.Main outcome measuresLoss of visual acuity.ResultsVisual acuity as measured by the Early Treatment Diabetic Retinopathy Study (ETDRS) eye chart remained unchanged from baseline to 3 months in the first 3 participants. For 2 participants with 90-day follow-up, acuity increased from hand movements to 7 letters in 1 and by 15 letters in 1, representing an improvement equivalent to 3 lines. No one lost vision, and no serious adverse events were observed. Minor adverse events included a transient increase of intraocular pressure (IOP), exposure keratitis, subconjunctival hemorrhage, a sore throat, and a transient increase in neutralizing antibodies (NAbs) against AAV2 in 1 participant. All blood samples were negative for vector DNA.ConclusionsNo serious safety problems were observed in the first 5 participants enrolled in this phase I trial of virus-based gene transfer in this mitochondrial disorder. Additional study follow-up of these and additional participants planned for the next 4 years is needed to confirm these preliminary observations.
| S-EPMC5287094 | biostudies-literature
Project description:Leber hereditary optic neuropathy (LHON) is a mitochondrial genetic disease that preferentially causes blindness in young adult males, affecting about 1 in 25 000 of the British population. It is characterised by bilateral subacute loss of central vision owing to focal degeneration of the retinal ganglion cell layer and optic nerve. Over 95% of LHON cases are primarily the result of one of three mitochondrial DNA (mtDNA) point mutations, G3460A, G11778A, and T14484C, which all involve genes encoding complex I subunits of the respiratory chain. An intriguing feature of LHON is that only approximately 50% of males and approximately 10% of females who harbour a pathogenic mtDNA mutation actually develop the optic neuropathy. This marked incomplete penetrance and gender bias imply that additional mitochondrial and/or nuclear genetic factors must be modulating the phenotypic expression of LHON. It is also likely that environmental factors contribute to the onset of visual failure. However, these secondary precipitating factors remain poorly defined at present. In this review, we describe the natural history of this optic nerve disorder and highlight issues relating to clinical diagnosis, management, and genetic counselling. We also discuss the findings of recently published studies and the light they shed on the complex aetiology and pathophysiology of LHON.
| S-EPMC1735056 | biostudies-other
Project description:Leber hereditary optic neuropathy (LHON) is a genetic disorder primarily due to mutations of mitochondrial DNA (mtDNA). Environmental factors are thought to precipitate the visual failure and explain the marked incomplete penetrance of LHON, but previous small studies have failed to confirm this to be the case. LHON has no treatment, so identifying environmental triggers is the key to disease prevention, whilst potentially revealing new mechanisms amenable to therapeutic manipulation. To address this issue, we conducted a large, multicentre epidemiological study of 196 affected and 206 unaffected carriers from 125 LHON pedigrees known to harbour one of the three primary pathogenic mtDNA mutations: m.3460G>A, m.11778G>A and m.14484T>C. A comprehensive history of exposure to smoking, alcohol and other putative environmental insults was collected using a structured questionnaire. We identified a strong and consistent association between visual loss and smoking, independent of gender and alcohol intake, leading to a clinical penetrance of 93% in men who smoked. There was a trend towards increased visual failure with alcohol, but only with a heavy intake. Based on these findings, asymptomatic carriers of a LHON mtDNA mutation should be strongly advised not to smoke and to moderate their alcohol intake.
| S-EPMC2732267 | biostudies-literature
Project description:ImportanceLimited studies have assessed the long-term benefit/risk of gene therapy for Leber hereditary optic neuropathy (LHON).ObjectiveTo determine the safety and efficacy of lenadogene nolparvovec in patients with LHON due to the MT-ND4 gene variant for up to 5 years after administration.Design, setting, and participantsThe RESCUE and REVERSE Long-Term Follow-up Study (RESTORE), conducted from 2018 to 2022, is the 5-year follow-up study of the 2 phase 3 clinical studies RESCUE (Efficacy Study of Lenadogene Nolparvovec for the Treatment of Vision Loss Up to 6 Months From Onset in LHON Due to the MT-ND4 Mutation) and REVERSE (Efficacy Study of Lenadogene Nolparvovec for the Treatment of Vision Loss From 7 Months to 1 Year From Onset in LHON Due to the MT-ND4 Mutation). At the end of each study, ie, 2 years after gene therapy administration, patients were offered enrollment in the RESTORE trial, a multinational, multicenter, prospective study, for an additional 3 years of follow-up. Patients with LHON due to the MT-ND4 gene variant received lenadogene nolparvovec in 1 eye and a sham injection in the other eye.InterventionLenadogene nolparvovec was administered as a single intravitreal injection in the RESCUE/REVERSE studies.Main outcomes and measuresMeasures included best-corrected visual acuity (BCVA), quality of life using the National Eye Institute visual functioning questionnaire 25 (NEI VFQ-25), and adverse events.ResultsAmong the 76 patients who received gene therapy in the RESCUE (n = 39) and REVERSE (n = 37) studies, 72 (94.7%) completed these studies; 62 patients (81.6%) participated in the RESTORE trial, and 55 patients (72.4%) completed the 5-year follow-up. Participants were mostly male (49 [79.0%]) with a mean (SD) age of 35.9 (15.3) years at treatment. At baseline, the mean (SD) BCVA was 1.5 (0.5) logMAR (20/600 Snellen) in eyes to be treated with lenadogene nolparvovec and 1.4 (0.5) logMAR (20/500) in sham eyes. At the end of the RESCUE/REVERSE trials, ie, 2 years after treatment, eyes treated with lenadogene nolparvovec and eyes treated with sham reached a mean BCVA value of 1.4 (0.6) logMAR (20/500). The mean (SD) change from baseline to year 2 was -0.05 (0.6) logMAR (+1 line) and 0.01 (0.6) logMAR (-0 line) in gene therapy-treated and sham eyes, respectively (difference, -0.03; 95% CI, -0.16 to 0.09; P = .60). Five years after treatment, the bilateral improvement from nadir was similar to that observed at 2 years, with a mean (SD) change in BCVA of -0.4 (0.5) logMAR (more than +4 lines) for eyes treated with lenadogene nolparvovec and -0.4 (0.4) logMAR (+4 lines) for eyes treated with sham (difference, -0.05; 95% CI, -0.15 to 0.04; P = .27). An improvement of at least -0.3 logMAR (+3 lines) from the nadir in at least 1 eye was observed in 66.1% of participants (41 of 62). Between 2 and 5 years, intraocular inflammation was noted in 4 participants with 8 events in eyes treated with lenadogene nolparvovec and 1 event in an eye treated with sham.Conclusions and relevanceIn this analysis of the RESTORE trial, follow-up of patients with LHON due to the MT-ND4 gene variant unilaterally treated with lenadogene nolparvovec demonstrated a sustained bilateral improvement in BCVA and a good safety profile up to 5 years after treatment. This evidence of persistent benefit over time is promising for the use of gene therapy in these patients.Trial registrationClinicalTrials.gov Identifier: NCT03406104.
| S-EPMC11843360 | biostudies-literature
Project description:Leber hereditary optic neuropathy (LHON) is one of the most common inherited optic neuropathies causing bilateral central vision loss. The disorder results from point mutations in mitochondrial DNA and subsequent mitochondrial dysfunction. The primary cell type that is lost in LHON is the retinal ganglion cell, which is highly susceptible to disrupted ATP production and oxidative stress. Inheritance of LHON follows that of mitochondrial genetics, and it has a highly variable clinical phenotype, as other genetic and environmental factors also play a role. Although LHON usually presents with isolated vision loss, some patients suffer other neurological sequelae. For ill-defined reasons, male LHON mutation carriers are more affected than females. Most LHON patients remain legally blind, but a small proportion can experience spontaneous partial recovery, often within the first year of symptom onset. Unfortunately, at this time there are no established curative interventions and treatment is largely supportive. Patients should be offered low vision services and counseled on mitigating risk factors for additional vision loss, such as smoking and consuming alcohol. Encouraging treatments currently undergoing investigation includes ubiquinone analogs, such as idebenone, as well as gene therapy and stem cells to restore ATP synthesis and provide neuroprotection to surviving retinal ganglion cells.
| S-EPMC4492634 | biostudies-other
Project description: Not available
| S-EPMC8478322 | biostudies-literature
Project description:PURPOSE OF REVIEW:Leber hereditary optic neuropathy (LHON) is the most common primary mitochondrial DNA (mtDNA) genetic disorder in the population. We address the clinical evolution of the disease, the secondary etiological factors that could contribute to visual loss, and the challenging task of developing effective treatments. RECENT FINDINGS:LHON is characterized by a preclinical phase that reflects retinal ganglion cell (RGC) dysfunction before rapid visual deterioration ensues. Children can present atypically with slowly progressive visual loss or an insidious/subclinical onset that frequently results in considerable diagnostic delays. The LHON mtDNA mutation is not sufficient on its own to precipitate RGC loss and the current body of evidence supports a role for smoking and estrogen levels influencing disease conversion. Clinical trials are currently investigating the efficacy of adeno-associated viral vectors-based gene therapy approaches for patients carrying the m.11778G>A mutation. Mitochondrial replacement therapy is being developed as a reproductive option to prevent the maternal transmission of pathogenic mtDNA mutations. SUMMARY:LHON is phenotypically more heterogeneous than previously considered and a complex interplay of genetic, environmental and hormonal factors modulates the risk of a LHON carrier losing vision. Advances in disease modelling, drug screening and genetic engineering offer promising avenues for therapeutic breakthroughs in LHON.
| S-EPMC5562441 | biostudies-literature
Project description:IMPORTANCE We developed a novel strategy for treatment of Leber hereditary optic neuropathy (LHON) caused by a mutation in the nicotinamide adenine dinucleotide dehydrogenase subunit IV (ND4) mitochondrial gene. OBJECTIVE To demonstrate the safety and effects of the gene therapy vector to be used in a proposed gene therapy clinical trial. DESIGN AND SETTING In a series of laboratory experiments, we modified the mitochondrial ND4 subunit of complex I in the nuclear genetic code for import into mitochondria. The protein was targeted into the organelle by agency of a targeting sequence (allotopic expression). The gene was packaged into adeno-associated viral vectors and then vitreally injected into rodent, nonhuman primate, and ex vivo human eyes that underwent testing for expression and integration by immunohistochemical analysis and blue native polyacrylamide gel electrophoresis. During serial follow-up, the animal eyes underwent fundus photography, optical coherence tomography, and multifocal or pattern electroretinography. We tested for rescue of visual loss in rodent eyes also injected with a mutant G11778A ND4 homologue responsible for most cases of LHON. EXPOSURE Ocular infection with recombinant adeno-associated viral vectors containing a wild-type allotopic human ND4 gene. MAIN OUTCOMES AND MEASURES Expression of human ND4 and rescue of optic neuropathy induced by mutant human ND4. RESULTS We found human ND4 expressed in almost all mouse retinal ganglion cells by 1 week after injection and ND4 integrated into the mouse complex I. In rodent eyes also injected with a mutant allotopic ND4, wild-type allotopic ND4 prevented defective adenosine triphosphate synthesis, suppressed visual loss, reduced apoptosis of retinal ganglion cells, and prevented demise of axons in the optic nerve. Injection of ND4 in the ex vivo human eye resulted in expression in most retinal ganglion cells. Primates undergoing vitreal injection with the ND4 test article and followed up for 3 months had no serious adverse reactions. CONCLUSIONS AND RELEVANCE Expression of our allotopic ND4 vector in the ex vivo human eye, safety of the test article, rescue of the LHON mouse model, and the severe irreversible loss of visual function in LHON support clinical testing with mutated G11778A mitochondrial DNA in our patients.
| S-EPMC4266107 | biostudies-literature
Project description:PurposeTo assess safety of gene therapy in G11778A Leber hereditary optic neuropathy (LHON).DesignPhase 1 clinical trial.MethodsSetting: single institution.ParticipantsPatients with G11778A LHON and chronic bilateral visual loss >12 months (group 1, n = 11), acute bilateral visual loss <12 months (group 2, n = 9), or unilateral visual loss (group 3, n = 8).Interventionunilateral intravitreal AAV2(Y444,500,730F)-P1ND4v2 injection with low, medium, high, and higher doses to worse eye for groups 1 and 2 and better eye for group 3.Outcome measuresBest-corrected visual acuity (BCVA), adverse events, and vector antibody responses. Mean follow-up was 24 months (range, 12-36 months); BCVAs were compared with a published prospective natural history cohort with designated surrogate study and fellow eyes.ResultsIncident uveitis (8 of 28, 29%), the only vector-related adverse event, resulted in no attributable vision sequelae and was related to vector dose: 5 of 7 (71%) higher-dose eyes vs 3 of 21 (14%) low-, medium-, or high-dose eyes (P < .001). Incident uveitis requiring treatment was associated with increased serum AAV2 neutralizing antibody titers (p=0.007) but not serum AAV2 polymerase chain reaction. Improvements of ≥15-letter BCVA occurred in some treated and fellow eyes of groups 1 and 2 and some surrogate study and fellow eyes of natural history subjects. All study eyes (BCVA ≥20/40) in group 3 lost ≥15 letters within the first year despite treatment.ConclusionsG11778A LHON gene therapy has a favorable safety profile. Our results suggest that if there is an efficacy effect, it is likely small and not dose related. Demonstration of efficacy requires randomization of patients to a group not receiving vector in either eye.
| S-EPMC9444871 | biostudies-literature
Project description:PurposeThere are many similarities in the clinical presentation of Leber hereditary optic neuropathy (LHON) and in patients who have optic neuropathy and a history of heavy tobacco and alcohol consumption. The main objective of this study is to investigate the frequency of primary and secondary mitochondrial DNA (mtDNA) mutations for LHON in patients diagnosed as having alcohol and tobacco optic neuropathy (ATON).MethodsTwenty-six patients who had a history of heavy alcohol and tobacco consumption and who developed bilateral optic neuropathy were tested for primary mutations (G11778A, T14484C, and G3460A) by restriction analysis, and 14 secondary mutations in the genes mitochondrially encoded NADH dehydrogenase 1 (MT-ND1), mitochondrially encoded NADH dehydrogenase 4 (MT-ND4), mitochondrially encoded NADH dehydrogenase 4L (MT-ND4L), mitochondrially encoded NADH dehydrogenase 5 (MT-ND5), mitochondrially encoded NADH dehydrogenase 6 (MT-ND6), and mitochondrially encoded cytochrome B (MT-CYB) by direct sequencing.ResultsFour (15.4%) of 26 patients tested positive for LHON primary mutations, two for the G11778A mutation, and two for the T14484C mutation. No patient tested positive for any of the 14 secondary mutations. Familial recurrence was present in four patients, and only three of these patients have presented the LHON mutation.ConclusionsThe diagnosis of LHON should be considered in all patients diagnosed as having optic neuropathy, particularly those with familial recurrence of vision loss.
| S-EPMC3244475 | biostudies-literature