Autosomal dominant optic atrophy (ADOA) is a rare progressive disease mainly caused by mutations in OPA1, a nuclear gene encoding for a mitochondrial protein that plays an essential role in mitochondrial dynamics, cell survival, oxidative phosphorylation, and mtDNA maintenance. ADOA is characterized by the degeneration of retinal ganglion cells (RGCs). This causes visual loss, which can lead to legal blindness in many cases. Nowadays, there is no effective treatment for ADOA. In this article, we have established an isogenic human RGC model for ADOA using iPSC technology and the genome editing tool CRISPR/Cas9 from a previously generated iPSC line of an ADOA plus patient harboring the pathogenic variant NM_015560.3: c.1861C>T (p.Gln621Ter) in heterozygosis in OPA1. To this end, a protocol based on supplementing the iPSC culture media with several small molecules and defined factors trying to mimic embryonic development has been employed. Subsequently, the created model was validated, confirming the presence of a defect of intergenomic communication, impaired mitochondrial respiration, and an increase in apoptosis and ROS generation. Finally, we propose the analysis of OPA1 expression by qPCR as an easy read-out method to carry out future drug screening studies using the created RGC model. In summary, this model provides a useful platform for further investigation of the underlying pathophysiological mechanisms of ADOA plus and for testing compounds with potential pharmacological action.

BACKGROUND: Copy number variations (CNVs) have emerged as significant contributors to the elusive genetic causality of inherited eye diseases. In this study, we describe a case with optic atrophy and a brain aneurysm, in which a de novo CNV 3q29 deletion was identified.
METHODS: A 40-year-old female patient was referred to our department after undergoing aneurysm transcatheter arterial embolization for a brain aneurysm. She had no history of systemic diseases, except for unsatisfactory best-corrected visual acuity (BCVA) since elementary school. Electrophysiological tests confirmed the findings in retinal images, indicating optic nerve atrophy. Chromosomal microarray analysis revealed a de novo deletion spanning 960 kb on chromosome 3q29, encompassing OPA1 and six neighboring genes. Unlike previously reported deletions in this region associated with optic atrophy, neuropsychiatric disorders, and obesity, this patient displayed a unique combination of optic atrophy and a brain aneurysm. However, there is no causal relationship between the brain aneurysm and the CNV.
CONCLUSIONS: In conclusion, the optic atrophy is conclusively attributed to the OPA1 deletion, and the aneurysm could be a coincidental association. The report emphasizes the likelihood of underestimating OPA1 deletions due to sequencing technology limitations. Recognizing these constraints, healthcare professionals must acknowledge these limitations and consistently search for OPA1 variants/deletions in Autosomal Dominant Optic Atrophy (ADOA) patients with negative sequencing results. This strategic approach ensures a more comprehensive exploration of copy-number variations, ultimately enhancing diagnostic precision in the field of genetic disorders.

Background: Blue-yellow axis dyschromatopsia is well-known in Autosomal Dominant Optic Atrophy (ADOA) patients, but there were no data on the correlation between retinal structure and short-wavelength automated perimetry (SWAP) values in this pathology. Methods: In this cross-sectional case-control study, we assessed the correlation between best corrected visual acuity (BCVA), standard automated perimetry (SAP), SWAP, and optical coherence tomography (OCT) parameters of 9 ADOA patients compared with healthy controls. Correlation analysis was performed between BCVA, mean deviation, pattern standard deviation (PSD), and fovea sensitivity (FS) values and the OCT thickness of each retinal layer and the peripapillary retinal nerve fiber layer (pRNFL). Results: The following significant and strong correlations were found: between BCVA and ganglion cell layer (GCL) and the global (G) pRNFL thicknesses; between SAP FS and GCL and the G-pRNFL thicknesses; between SWAP PSD and total retina, GCL, inner plexiform layer, inner nuclear layer, inner retinal layer and the temporal pRNFL thicknesses. We found a constant shorter duration of the SITA-SWAP compared with the SITA-STANDARD strategy. Conclusions: SWAP, SAP, and BCVA values provided relevant clinical information about retinal involvement in our ADOA patients. The perimetric functional parameters that seemed to correlate better with structure involvement were FS on SAP and PSD on SWAP.

Autosomal dominant optic atrophy (ADOA), mostly caused by heterozygous OPA1 mutations and characterized by retinal ganglion cell (RGC) loss and optic nerve degeneration, is one of the most common types of inherited optic neuropathies. Previous work using a two-dimensional (2D) differentiation model of induced pluripotent stem cells (iPSCs) has investigated ADOA pathogenesis but failed to agree on the effect of OPA1 mutations on RGC differentiation. Here, we use 3D retinal organoids capable of mimicking in vivo retinal development to resolve the issue. We generated isogenic iPSCs carrying the hotspot OPA1 c.2708_2711delTTAG mutation and found that the mutant variant caused defective initial and terminal differentiation and abnormal electrophysiological properties of organoid-derived RGCs. Moreover, this variant inhibits progenitor proliferation and results in mitochondrial dysfunction. These data demonstrate that retinal organoids coupled with gene editing serve as a powerful tool to definitively identify disease-related phenotypes and provide valuable resources to further investigate ADOA pathogenesis and screen for ADOA therapeutics.

Autosomal dominant optic atrophy (ADOA) is frequently caused by mutations in the optic atrophy 1 (OPA1) gene, with haploinsufficiency being the major genetic pathomechanism. Almost 30% of the OPA1-associated cases suffer from splice defects. We identified a novel OPA1 mutation, c.1065+5G>A, in patients with ADOA. In patient-derived fibroblasts, the mutation led to skipping of OPA1 exon 10, reducing the OPA1 protein expression by approximately 50%. We developed a molecular treatment to correct the splice defect in OPA1 using engineered U1 splice factors retargeted to different locations in OPA1 exon 10 or intron 10. The strongest therapeutic effect was detected when U1 binding was engineered to bind to intron 10 at position +18, a position predicted by bioinformatics to be a promising binding site. We were able to significantly silence the effect of the mutation (skipping of exon 10) and simultaneously increase the expression level of normal transcripts. Retargeting U1 to the canonical splice donor site did not lead to a detectable splice correction. This proof-of-concept study indicates for the first time the feasibility of splice mutation correction as a treatment option for ADOA. Increasing the amount of correctly spliced OPA1 transcripts may suffice to overcome the haploinsufficiency.

Hereditary optic neuropathy (HON) is a group of genetically heterogeneous diseases that cause optic nerve atrophy and lead to substantial visual impairment. HON may present with optic nerve atrophy only or in association with various systemic abnormalities. Although a genetic survey is indispensable for diagnosing HON, conventional sequencing techniques could render its diagnosis challenging. In this study, we attempted to explore the genetic background of patients with HON in Taiwan through capture-based next-generation sequencing targeting 52 HON-related genes. In total, 57 patients from 48 families were recruited, with 6 patients diagnosed as having Leber hereditary optic neuropathy through initial screening for three common variants (m.3460G>A, m.11778G>A, m.14484T>C). Disease-causing genotypes were identified in 14 (33.3%) probands, and OPA1 variants were the most prevalent cause of autosomal HON. Exposure to medications such as ethambutol could trigger an attack of autosomal dominant optic atrophy. WFS1 variants were identified in three probands with variable clinical features in our cohort. Hearing impairment could occur in patients with OPA1 or WFS1 variants. This is the first comprehensive study investigating the genetic characteristics of HON in Taiwan, especially for autosomal HON. Our results could provide useful information for clinical diagnosis and genetic counseling in this field.

Visual hallucinations in Parkinson\'s disease (PD) are usually attributed to medications and dysfunction in higher order sensory processing as the disease progresses. However deficits in visual processing, including colour discrimination, have been reported in early, untreated PD and it is unclear how these, along with co-morbid conditions affecting vision, could contribute to hallucinations. This case describes a 66-year-old otherwise fully independent woman with early, mild PD who presented with discrete episodes of unusual vivid hallucinations centred on colour. She was later found to have a subclinical colour deficiency in excess of her PD and, after reporting a lifelong history of poor vision in her father, tested positive for autosomal dominant optic atrophy. This case illustrates how a lifelong extrinsic deficiency in colour vision can interact with the effects of visual changes in early stage PD and medication to provoke colour hallucinations. It therefore emphasises the importance of full ophthalmological work up in similar cases where hallucinations are atypical and unexpected for the severity and stage of PD.

OBJECTIVE: To assess retinal vascular involvement in patients with autosomal dominant optic atrophy (ADOA) genetically confirmed by the presence of the OPA1 (Optic Atrophy 1) gene mutation using a multimodal protocol of investigation of retinal posterior pole.
METHODS: In this cross-sectional, case-control, observational study, both eyes of 13 patients with a genetic diagnosis of ADOA were compared with both eyes of 13 healthy controls (HCs). All subjects underwent full ophthalmological examination, spectral domain-optical coherence tomography (SD-OCT), fundus perimetry (FP) and OCT angiography (OCTA).
RESULTS: Vessel density (VD) of the superficial and deep macular vascular plexi and of the radial peripapillary capillary plexus were significantly decreased (p ≤ 0.001) in ADOA patients compared with HCs. The area under the receiver operating characteristics analysis also revealed high values of sensitivity and specificity of OCTA parameters in distinguish between patients and HCs. A strong correlation (Pearson Coefficient, r = 0.91) emerged between OCTA VD of the superficial retinal plexus and the average Ganglion Cell Layer (GCL) thickness as measured by SD-OCT; a slightly lower correlation (Pearson Coefficient, r = 0.89) was also found between VD of the deep plexus and the average GCL thickness of the same eyes in patients with ADOA. The correlation among values of differential light sensitivity (DLS) measured by FP with VD and GCL thickness parameters was also investigated. The correlation analysis among DLS and the VD parameters showed from low-to-moderate correlation (ranging from r = 0.29 for the deep fovea VD to r = 0.59 for the deep whole image VD). The correlation coefficient between the mean DLS and the average thickness of GCL was more significant (Pearson Coefficient, r = 0.75). A significant correlation emerged also between the VD and the visual acuity, in terms of LogMAR BCVA (best-corrected visual acuity), especially for the VD of the deep capillary plexus (Pearson Coefficient for the Deep whole Image VD and LogMAR BCVA r = -0.75; for the Deep parafovea VD and LogMAR BCVA r = -0.78).
CONCLUSIONS: Retinal microvascular assessment by OCTA angiography can provide relevant clinical information on retinal involvement in ADOA patients. In patients with genetically confirmed OPA1-related ADOA, there is a decrease in retinal vessel density associated with GCL thinning and DLS reduction.

Leber hereditary optic neuropathy (LHON) and autosomal dominant optic atrophy (ADOA) are the two commonest forms of hereditary optic neuropathy. The aim of this study was to comprehensively investigate the incidence and spectrum of mutations in patients with suspected hereditary optic neuropathy by combining mitochondrial DNA (mtDNA) genome-wide and targeted exon sequencing.
A cohort of 1101 subjects were recruited to participate in the study, comprising 177 families (177 probands and their family members, a total of 537 subjects, including 254 patients) and 164 sporadic cases with suspected hereditary optic neuropathy, and 400 unrelated control subjects for genetic analysis: all subjects (including control subjects) underwent a comprehensive ophthalmologic examination and were subjected to sequencing analysis of mtDNA genome-wide and targeted exon. Overall, targeted exon sequencing was used to screen 792 genes associated with common hereditary eye diseases, and the mtDNA genome-wide were screened by next-generation sequencing.
We found variants detected in 168 (40.2%, 168/418) of the 418 patients screened. Among these, 132 cases (78.6%, 132/168) were detected with known LHON disease-causing mtDNA variants; 40 cases (23.8%, 40/168) were detected with nuclear DNA (ntDNA) variants, which included 36 cases (21.4%, 36/168) with detected OPA1 mutations, 4 patients (2.4%, 4/168) with detected OPA3 mutations, and 2 patients (1.2%, 2/168) with detected TMEM126A homozygous mutation. Coexistence variation (mtDNA/mtDNA [n = 16], ntDNA/ntDNA [n = 4], mtDNA/ntDNA [n = 7]) was found in 27 patients (16.4%, 27/165), including mtDNA/ntDNA coexistence variation that was detected in seven patients. Among these ntDNA mutations, 38 distinct disease-causing variants, including autosomal recessive heterozygous mutations, were detected, which included 22 novel variants and two de novo variants. Total haplogroup distribution showed that 34.5% (29/84) and 28.6% (24/84) of the affected subjects with m.11778G>A belonged to haplogroup D and M, with a high frequency of subhaplogroups D4, D5, and M7.
The LHON-mtDNA mutations are the commonest genetic defects in this Chinese cohort, followed by the OPA1 mutations. To our knowledge, this is the first comprehensive study of LHON, ADOA, and autosomal recessive optic atrophy combined with mtDNA genome-wide and targeted exon sequencing, as well as haplogroup analysis, in a large cohort of Chinese patients with suspected hereditary optic neuropathy. Our findings provide a powerful basis for genetic counseling in patients with suspected hereditary optic neuropathy.
We applied mtDNA genome-wide sequencing combined with panel-based targeted exon sequencing to explore the pathogenic variation spectrum and genetic characteristics of patients with suspected hereditary optic neuropathy, providing a comprehensive research strategy for clinical assistant diagnosis, treatment, and genetic counseling.

OBJECTIVE: To evaluate the macular and peripapillary morpho-vascular changes in ADOA, using optical coherence tomography (OCT) and OCT angiography (OCTA).
METHODS: Prospectively defined, cross-sectional case-control study. Consecutive patients with a genetic or clinical diagnosis of ADOA along with age- and sex-matched controls were included. The radial peripapillary capillary (RPC) density and vessel density (VD) in the parafoveal superficial and deep capillary plexuses (SCP and DCP, respectively) were evaluated with OCTA. The ganglion cell complex (GCC) and retinal nerve fiber layer (RNFL) thickness were determined using structural OCT. We applied a previously validated customized macro (Fiji, SciJava Consortium) to compute RPC density. The remaining parameters were calculated by the built-in software. Non-parametric methods were used for data analysis. The target α level was 0.05, which was adjusted through Bonferroni\'s correction when multiple outcomes were tested.
RESULTS: Fifty-eight eyes (n = 29 control; n = 29 ADOA) from 30 subjects (mean age 42.43 ± 15.30 years; 37.93% male) were included. Parafoveal SCP VD, GCC thickness, RPC VD in the temporal quadrant, as well as RNFL thickness in the nasal and temporal quadrants were decreased in ADOA eyes (all p < 0.001). When only patients with genetically confirmed diagnosis were included, capillary dropout in the circumpapillary superior and inferior quadrants also became evident (both p < 0.001). The GCC/parafoveal SCP ratio was increased in ADOA, relatively to matched controls. In contrast, none of the circumpapillary morpho-vascular ratios was significantly different in ADOA eyes.
CONCLUSIONS: The microvascular and structural changes found in ADOA suggest that both the macular and peripapillary regions are involved, although the threshold for damage of the structural and vascular components may be different for each region. Larger series with longitudinal follow-up may validate OCTA biomarkers helpful for disease monitoring.