Autosomal Dominant Optic Atrophy Plus

1. Disease Information

Overview

Autosomal Dominant Optic Atrophy Plus (DOA Plus) is the syndromic/multisystem form of OPA1-related dominant optic atrophy, characterized by progressive retinal ganglion cell and optic nerve degeneration with extra-ocular manifestations (wong2023opa1dominantoptic pages 1-3). DOA Plus represents approximately 20% of all OPA1 mutation carriers, extending beyond isolated optic atrophy to include multisystem involvement (wong2023opa1dominantoptic pages 1-3, nitta2024drosophilamodelto pages 1-2).

Key Identifiers

• OMIM: 165500 (DOA), 125250 (DOA Plus)
• Synonyms: Dominant optic atrophy, autosomal dominant optic atrophy (ADOA), Kjer type optic atrophy, Kjer syndrome, syndromic DOA
• Classification: Mendelian hereditary optic neuropathy (zeppieri2025isolatedandsyndromic pages 1-2, lee2024hereditaryopticneuropathies pages 1-2)

Note: MONDO, Orphanet, ICD-10/ICD-11, and MeSH identifiers were not available in the retrieved evidence.

Information Source

The information in this report is derived from aggregated disease-level resources, including peer-reviewed primary literature, systematic reviews, and clinical studies published 2021-2026, with prioritization of 2023-2024 sources as requested.

2. Etiology

Disease Causal Factors

Primary Genetic Cause: The OPA1 gene (chromosome 3q28-q29/3q29) is the major causal gene, accounting for 60-90% of autosomal dominant optic atrophy cases (wong2023opa1dominantoptic pages 1-3, arruti2023opa1dominantoptic pages 1-2, yao2025contrastingpathophysiologicalmechanisms pages 1-2). OPA1 encodes a ubiquitously expressed mitochondrial dynamin-like GTPase protein localized to the inner mitochondrial membrane (wong2023opa1dominantoptic pages 1-3, maresca2021molecularmechanismsbehind pages 1-3).

Mechanistic Basis: OPA1 is essential for mitochondrial inner membrane fusion, cristae structure maintenance, oxidative phosphorylation support, mitochondrial DNA (mtDNA) maintenance, mitophagy regulation, and apoptosis control (maresca2021molecularmechanismsbehind pages 1-3, amore2021therapeuticoptionsin pages 1-2). Dysfunction in these processes leads to selective vulnerability of retinal ganglion cells (wong2023opa1dominantoptic pages 1-3, strachan2021theroleof pages 1-2).

Risk Factors

Genetic Risk Factors:

Variant Type and Location: The severity and phenotypic spectrum of DOA correlate strongly with variant type and location. Missense mutations in the dynamin/GTPase domain are enriched in DOA Plus and thought to act via dominant-negative effects, whereas truncating mutations (deletions, splice-site, frameshift) typically cause haploinsufficiency (nitta2024drosophilamodelto pages 1-2, yao2025contrastingpathophysiologicalmechanisms pages 1-2, zanfardino2024opa1mutationaffects pages 1-2).

A 2025 mechanistic study contrasted two mutations: the missense variant c.1034G>A (p.Arg345Gln) caused >60% mitochondrial fragmentation with greater reactive oxygen species (ROS), cytochrome c release, and apoptosis, versus the splice-site variant c.1305+2delGT which caused ~20% fragmentation (yao2025contrastingpathophysiologicalmechanisms pages 1-2).

Representative Pathogenic Variants: - c.2708_2711delTTAG (OPA1delTTAG): Common recurrent pathogenic deletion - R445H: Classic DOA Plus-associated missense variant - c.1034G>A (p.Arg345Gln): GTPase domain missense - c.1305+2delGT: Splice-site variant - V465F and V560F: Domain-specific mutations studied in 2025 - c.1406_1407del (p.Thr469LysfsTer16): Newly reported in 2023 pediatric cohort - p.His42Tyr: ADOA Plus patient fibroblast study variant - ~69.86 kb deletion encompassing entire OPA1 gene (nitta2024drosophilamodelto pages 1-2, yao2025contrastingpathophysiologicalmechanisms pages 1-2, zhang2025opa1mutationsin pages 1-2, arruti2023opa1dominantoptic pages 1-2, zanfardino2024opa1mutationaffects pages 1-2)

Modifier Genes: While OPA1 is the primary causative gene, recent studies have identified additional genes associated with autosomal optic atrophy, including OPA3, OPA4, TMEM126A/OPA7, SCL25A46, MCAT, RTN4IP1/OPA10, WFS1, ACO2/OPA9, and AFG3L2, though these account for a minority of cases (strachan2021theroleof pages 1-2, zeppieri2025isolatedandsyndromic pages 1-2).

Environmental Risk Factors: No specific environmental risk factors were documented in the retrieved evidence for DOA Plus. The disease is primarily genetically determined.

Age and Sex: Typical onset is in the first or second decade of life, often in early childhood (arruti2023opa1dominantoptic pages 1-2, wong2023opa1dominantoptic pages 1-3). Sex distribution was not systematically reported in the retrieved literature for DOA Plus specifically.

Protective Factors

No genetic or environmental protective factors were identified in the retrieved evidence for DOA Plus.

Gene-Environment Interactions

No specific gene-environment interactions were documented in the retrieved evidence for DOA Plus.

3. Phenotypes

Core Ocular Phenotype

Primary Visual Manifestations: - Bilateral, insidious, progressive visual loss beginning in childhood - Dyschromatopsia/impaired color vision (classically tritanopia/blue-yellow defect) - Central or centrocecal scotomas on visual field testing - Temporal optic disc pallor on funduscopy - Retinal nerve fiber layer (RNFL) thinning, especially in papillomacular bundle - Ganglion cell layer (GCL) thinning on optical coherence tomography (OCT) (wong2023opa1dominantoptic pages 1-3, arruti2023opa1dominantoptic pages 1-2, lee2024hereditaryopticneuropathies pages 1-2, yao2025contrastingpathophysiologicalmechanisms pages 1-2)

Quantitative OCT Findings (Pediatric Cohort, n=11): In a 2023 pediatric study, mean baseline measurements included: - RNFL thickness: 81.6 µm (right eye), 80.5 µm (left eye) - Ganglion cell layer: 52.5 µm (right eye), 52.4 µm (left eye) - Central macular thickness: 229.5 µm (right eye), 233.5 µm (left eye) - 9/11 patients showed bilateral temporal disc pallor - Most common visual field defect: centrocecal scotoma (arruti2023opa1dominantoptic pages 1-2)

Suggested HPO Terms for Ocular Phenotype: - HP:0000618 (Blindness) - HP:0000529 (Progressive visual loss) - HP:0000543 (Optic disc pallor) - HP:0007663 (Reduced visual acuity) - HP:0000639 (Nystagmus) - when present - HP:0000613 (Photophobia) - when present

Extra-Ocular Phenotypes in DOA Plus

Sensorineural Hearing Loss/Deafness: Hearing loss is the most established and common extra-ocular feature, affecting approximately 20% of DOA Plus patients. It frequently manifests as auditory neuropathy spectrum disorder (ANSD) (affortit2024thehumanopa1delttag pages 1-2, kawakita2026frequencyandhearing pages 1-2).

In a 2026 cohort of 18,475 Japanese patients with hearing loss, 10 individuals from 8 families carried OPA1 variants. Hearing loss was typically: - Post-lingual onset - Progressive course - Mild-to-moderate severity - Associated with ANSD phenotype in missense variant carriers - 5 patients obtained limited benefit from hearing aids - 1 cochlear implant recipient achieved good speech perception (kawakita2026frequencyandhearing pages 1-2)

A 2024 mouse model (Opa1delTTAG) demonstrated adult-onset progressive auditory neuropathy with: - >40% reduction in Opa1 mRNA (haploinsufficiency mechanism) - Selective loss of sensory inner hair cells - Progressive degeneration of axons and myelin sheaths of spiral ganglion neurons - Age-related mtDNA depletion - Increased oxidative stress and mitophagy - Impaired autophagic flux (affortit2024thehumanopa1delttag pages 1-2)

Peripheral Neuropathy: Progressive peripheral neuropathy is frequently reported in DOA Plus (wong2023opa1dominantoptic pages 1-3, strachan2021theroleof pages 1-2).

Myopathy: Muscle weakness and myopathy are common manifestations (wong2023opa1dominantoptic pages 1-3, nitta2024drosophilamodelto pages 1-2).

Ataxia: Cerebellar ataxia affects a subset of DOA Plus patients (wong2023opa1dominantoptic pages 1-3, strachan2021theroleof pages 1-2).

Chronic Progressive External Ophthalmoplegia (CPEO): Progressive limitation of eye movements due to extraocular muscle involvement (wong2023opa1dominantoptic pages 1-3, chen2023mitochondriaandthe pages 1-2).

Neurological Complications: - Multiple sclerosis-like illness - Parkinsonism - Dementia (wong2023opa1dominantoptic pages 1-3, nitta2024drosophilamodelto pages 1-2)

Cardiomyopathy: Cardiac involvement is less common but reported in DOA Plus (wong2023opa1dominantoptic pages 1-3).

Suggested HPO Terms for Extra-Ocular Phenotypes: - HP:0000407 (Sensorineural hearing impairment) - HP:0009830 (Peripheral neuropathy) - HP:0003701 (Proximal muscle weakness/Myopathy) - HP:0001251 (Ataxia) - HP:0000602 (Ophthalmoplegia) - HP:0002071 (Abnormality of extrapyramidal motor function) - for Parkinsonism - HP:0000726 (Dementia) - HP:0001638 (Cardiomyopathy)

Phenotype Characteristics

Age of Onset: Typical onset in first or second decade of life, often early childhood (arruti2023opa1dominantoptic pages 1-2, wong2023opa1dominantoptic pages 1-3). However, expressivity is variable - some patients experience visual loss from birth, while others remain asymptomatic or develop symptoms in adulthood (sampige2025ittakestwo pages 1-2).

Severity: Visual acuity ranges from normal to detection of hand movements only. In a 2023 pediatric cohort, mean baseline visual acuity was 0.40 logMAR (right eye) and 0.44 logMAR (left eye), remaining largely unchanged over follow-up (arruti2023opa1dominantoptic pages 1-2).

Progression: Disease course is insidious and progressive. Visual impairment is typically bilateral and worsens over time. Half of all DOA patients fail driving standards and are registered as legally blind (wong2023opa1dominantoptic pages 1-3).

Frequency: DOA Plus affects approximately 20% of OPA1 mutation carriers, with the remaining 80% presenting with isolated optic atrophy (wong2023opa1dominantoptic pages 1-3, nitta2024drosophilamodelto pages 1-2, strachan2021theroleof pages 1-2).

Quality of Life Impact

DOA carries a significant detrimental impact on quality of life, with high rates of psychological distress and great societal costs. DOA Plus adds additional morbidity through hearing impairment, neurological, and muscular complications, further reducing quality of life (wong2023opa1dominantoptic pages 1-3, kawakita2026frequencyandhearing pages 1-2).

4. Genetic/Molecular Information

Causal Genes

Primary Gene: - OPA1 (OMIM 605290, chromosome 3q29) - Gene structure: Spans >90 kbp genomic DNA, composed of 30 exons (alternative reports: 31 exons) - Alternative splicing generates 8 different isoforms - Translated to Long (L-OPA1, ~120 kDa) and Short (S-OPA1, ~80 kDa) forms (wong2023opa1dominantoptic pages 1-3, arruti2023opa1dominantoptic pages 1-2, maresca2021molecularmechanismsbehind pages 1-3)

Additional Genes: While OPA1 accounts for 60-90% of cases, other genes associated with autosomal optic atrophy include OPA3, OPA4, TMEM126A/OPA7, SCL25A46, MCAT, RTN4IP1/OPA10, WFS1, ACO2/OPA9, and AFG3L2 (strachan2021theroleof pages 1-2, zeppieri2025isolatedandsyndromic pages 1-2).

Pathogenic Variants

Variant Distribution: More than 500 variants in OPA1 are thought to be pathogenic. Of these: - 28% are missense (mostly in GTPase domain) - 24% cause aberrant splicing - 22% cause frameshifts - Additional variants include nonsense, deletions, insertions, and copy number variants (wong2023opa1dominantoptic pages 1-3, strachan2021theroleof pages 1-2)

Variant Classification: Three variants from the 2026 hearing-loss cohort were classified as pathogenic or likely pathogenic, while five were variants of uncertain significance (VUS) (kawakita2026frequencyandhearing pages 1-2).

Allele Frequency: Specific population allele frequencies were not systematically reported in the retrieved evidence.

Somatic vs Germline: All documented OPA1 variants associated with DOA/DOA Plus are germline mutations (wong2023opa1dominantoptic pages 1-3, yao2025contrastingpathophysiologicalmechanisms pages 1-2).

Functional Consequences:

Haploinsufficiency Mechanism: Many truncating mutations (deletions, splice-site, frameshift) result in reduced OPA1 protein levels, causing disease through haploinsufficiency. The mouse Opa1delTTAG model demonstrated >40% reduction in Opa1 mRNA levels, supporting this mechanism (affortit2024thehumanopa1delttag pages 1-2, nitta2024drosophilamodelto pages 1-2).

Dominant-Negative Mechanism: Missense mutations, particularly in the GTPase domain, are thought to exert dominant-negative effects. These mutant proteins can oligomerize with wild-type OPA1, disrupting normal function more severely than simple haploinsufficiency (nitta2024drosophilamodelto pages 1-2, yao2025contrastingpathophysiologicalmechanisms pages 1-2, zanfardino2024opa1mutationaffects pages 1-2).

A 2024 Drosophila study successfully distinguished loss-of-function from dominant-negative mutations, demonstrating that DOA Plus mutations suppressed rescue by wild-type OPA1, supporting dominant-negative action (nitta2024drosophilamodelto pages 1-2).

Modifier Genes

While not extensively characterized in the retrieved evidence, the variable expressivity of DOA/DOA Plus suggests the involvement of genetic modifiers, though specific genes were not identified.

Epigenetic Information

No specific epigenetic modifications (DNA methylation, histone modifications) were documented in the retrieved evidence for DOA Plus.

Chromosomal Abnormalities

Large-scale deletions encompassing the OPA1 gene have been identified, including a ~69.86 kb deletion in the 3q29 region (yao2025contrastingpathophysiologicalmechanisms pages 1-2).

5. Environmental Information

No specific environmental factors, lifestyle factors, or infectious agents contributory to DOA Plus were identified in the retrieved evidence. The disease is primarily genetically determined.

6. Mechanism / Pathophysiology

Molecular Pathways

OPA1 Function in Mitochondrial Homeostasis: OPA1 is a multifunctional protein central to mitochondrial homeostasis, regulating: 1. Mitochondrial inner membrane fusion 2. Cristae architecture and remodeling 3. Oxidative phosphorylation (OXPHOS) efficiency 4. Mitochondrial DNA maintenance 5. Mitophagy and quality control 6. Apoptosis regulation (maresca2021molecularmechanismsbehind pages 1-3, amore2021therapeuticoptionsin pages 1-2, dotto2021dominantopticatrophy pages 1-2)

Disrupted Pathways in DOA Plus:

Mitochondrial Dynamics: OPA1 dysfunction disrupts the balance between mitochondrial fusion and fission, leading to excessive fragmentation. The extent of fragmentation correlates with variant type: missense variants in the GTPase domain cause >60% fragmentation, while truncating variants cause ~20% fragmentation (yao2025contrastingpathophysiologicalmechanisms pages 1-2).

OXPHOS Dysfunction: Impaired cristae structure and fusion directly compromise OXPHOS efficiency, reducing ATP production. This is particularly detrimental to metabolically active retinal ganglion cells (maresca2021molecularmechanismsbehind pages 1-3, amore2021therapeuticoptionsin pages 1-2).

mtDNA Maintenance: OPA1 is essential for mtDNA stability. Age-related mtDNA depletion was documented in the Opa1delTTAG mouse model (affortit2024thehumanopa1delttag pages 1-2).

Cellular Processes

Mitochondrial Fragmentation: Depending on variant type, 20-60% of mitochondria become fragmented in OPA1-deficient cells (yao2025contrastingpathophysiologicalmechanisms pages 1-2, zhang2025opa1mutationsin pages 1-2).

Membrane Potential Loss: OPA1 mutations cause deficits in mitochondrial membrane potential maintenance, with domain-specific effects. The BSE domain mutation V560F caused greater membrane potential deficits than the GTPase domain mutation V465F (zhang2025opa1mutationsin pages 1-2).

ROS Production: Increased reactive oxygen species generation occurs secondary to OXPHOS dysfunction and mitochondrial fragmentation (yao2025contrastingpathophysiologicalmechanisms pages 1-2, affortit2024thehumanopa1delttag pages 1-2).

Apoptosis: OPA1 mutations lead to: - Cytochrome c release from mitochondria - Increased cell death under apoptotic stimuli - Domain-specific effects (BSE mutations cause earlier apoptosis than GTPase mutations) (zhang2025opa1mutationsin pages 1-2, yao2025contrastingpathophysiologicalmechanisms pages 1-2)

Autophagy and Mitophagy: A 2024 fibroblast study from an ADOA Plus patient demonstrated: - Disrupted mitochondrial network - Altered mitochondrial dynamics - Reduced autophagic response - Impaired autophagic flux - Enhanced mitophagy response (observed in some models) (zanfardino2024opa1mutationaffects pages 1-2, affortit2024thehumanopa1delttag pages 1-2)

Cellular Senescence: A novel 2024 finding identified premature senescence in ADOA Plus patient fibroblasts, suggesting a previously unexplored role of OPA1 in cellular aging (zanfardino2024opa1mutationaffects pages 1-2).

Protein Dysfunction

Structural Impact: Protein structure prediction using AlphaFold2 revealed that: - Missense variant c.1034G>A (p.Arg345Gln) caused minimal secondary structure alteration - Splice-site variant c.1305+2delGT resulted in loss of amino acids 411-435, significantly affecting normal secondary structure (yao2025contrastingpathophysiologicalmechanisms pages 1-2)

Domain-Specific Effects: - GTPase domain mutations (e.g., V465F) impair mitochondrial fusion and cell survival - BSE α-helix domain mutations (e.g., V560F) cause greater deficits in membrane potential, earlier apoptosis, and distinct molecular pathway changes (zhang2025opa1mutationsin pages 1-2)

OPA1 Isoform Processing: OPA1 exists as Long (L-OPA1) and Short (S-OPA1) forms. The balance between these forms is critical for function, with mutations affecting processing and stoichiometry (arruti2023opa1dominantoptic pages 1-2, strachan2021theroleof pages 1-2).

Metabolic Changes

Energy Metabolism: OXPHOS deficiency leads to reduced ATP production, particularly affecting high-energy-demand cells like retinal ganglion cells and neurons (maresca2021molecularmechanismsbehind pages 1-3, amore2021therapeuticoptionsin pages 1-2).

Oxidative Stress: Increased ROS production causes oxidative stress, contributing to cellular damage (yao2025contrastingpathophysiologicalmechanisms pages 1-2, affortit2024thehumanopa1delttag pages 1-2).

Immune System Involvement

No specific immune system involvement was documented in the retrieved evidence for DOA Plus.

Tissue Damage Mechanisms

Selective RGC Vulnerability: Retinal ganglion cells are particularly vulnerable to mitochondrial dysfunction due to: - High metabolic demands - Long, unmyelinated intra-retinal axonal segments - Energy dependence for maintaining membrane potential and axonal transport (maresca2021molecularmechanismsbehind pages 1-3, strachan2021theroleof pages 1-2, rufa2025serumneuronalglial pages 1-8)

Progressive Degeneration: In DOA Plus, degeneration extends beyond RGCs to: - Auditory neurons (inner hair cells, spiral ganglion neurons) - Peripheral nerves - Muscle tissue - Central nervous system structures (affortit2024thehumanopa1delttag pages 1-2, kawakita2026frequencyandhearing pages 1-2)

Biochemical Abnormalities

Enzyme/Protein Dysfunction: OPA1 is a GTPase enzyme. Mutations in the GTPase domain directly impair GTPase activity, compromising fusion activity (zhang2025opa1mutationsin pages 1-2, wong2023opa1dominantoptic pages 1-3).

Mitochondrial Protein Import: The N-terminal mitochondrial targeting sequence (MTS) facilitates OPA1 import. Mutations affecting this region may impair protein localization (zanfardino2024opa1mutationaffects pages 1-2).

Molecular Profiling

Transcriptomics: Gene set variation analysis and enrichment analysis revealed distinct molecular signatures associated with different OPA1 mutations (V465F vs V560F), indicating domain-specific transcriptional responses (zhang2025opa1mutationsin pages 1-2).

RNA sequencing in ADOA Plus fibroblasts identified altered gene expression patterns related to autophagy, mitophagy, and senescence (zanfardino2024opa1mutationaffects pages 1-2).

Proteomics: Not systematically addressed in the retrieved evidence.

Metabolomics/Lipidomics: Not systematically addressed in the retrieved evidence.

Advanced Technologies

Single-Cell Analysis: Not reported in the retrieved evidence for DOA Plus.

iPSC-Derived Models: Patient-derived induced pluripotent stem cell (iPSC) lines were generated from two DOA patients in 2023 for RGC differentiation and disease modeling, enabling correlation of cellular phenotypes with clinical features (zanfardino2024opa1mutationaffects pages 1-2, dotto2021dominantopticatrophy pages 1-2).

Functional Genomics: Not systematically reported in the retrieved evidence.

Causal Chain Summary

The pathogenic cascade in DOA Plus proceeds as follows:

1. Initial trigger: OPA1 gene mutation (missense, truncating, or deletion)
2. Protein-level effect: Reduced OPA1 function (haploinsufficiency) or dominant-negative interference
3. Mitochondrial dysfunction: Impaired fusion → mitochondrial fragmentation → disrupted cristae → OXPHOS deficiency
4. Cellular consequences: ATP depletion, ROS production, membrane potential loss, mtDNA instability, impaired autophagy, premature senescence
5. Cell death: Cytochrome c release → apoptosis of vulnerable neurons
6. Tissue-level manifestation: RGC degeneration → optic atrophy; auditory neuron loss → hearing impairment; peripheral nerve/muscle degeneration → neuropathy/myopathy
7. Clinical outcome: Progressive vision loss, deafness, neurological symptoms

Suggested Ontology Terms:

GO Biological Processes: - GO:0000266 (mitochondrial fission) - GO:0008053 (mitochondrial fusion) - GO:0006915 (apoptotic process) - GO:0000422 (autophagy of mitochondrion/mitophagy) - GO:0006119 (oxidative phosphorylation) - GO:0007569 (cell aging)

GO Cellular Components: - GO:0005743 (mitochondrial inner membrane) - GO:0005739 (mitochondrion) - GO:0005759 (mitochondrial matrix)

Cell Types (CL Terms): - CL:0000740 (retinal ganglion cell) - CL:0000199 (mechanoreceptor cell) - for auditory hair cells - CL:0000540 (neuron) - CL:0000187 (muscle cell)

7. Anatomical Structures Affected

Organ Level

Primary Organ: - Eye (optic nerve, retina) - universally affected in DOA/DOA Plus

Secondary Organ Involvement (DOA Plus): - Inner ear (cochlea, spiral ganglion) - Peripheral nervous system - Skeletal muscle - Central nervous system (cerebellum, basal ganglia, cerebral cortex) - Heart (cardiomyopathy in subset of cases) (wong2023opa1dominantoptic pages 1-3, affortit2024thehumanopa1delttag pages 1-2, kawakita2026frequencyandhearing pages 1-2)

Body Systems: - Visual system - Auditory system - Peripheral nervous system - Central nervous system - Musculoskeletal system - Cardiovascular system (less commonly)

Tissue and Cell Level

Specific Tissue Types: - Nervous tissue (retinal neurons, auditory neurons, peripheral nerves, central neurons) - Muscle tissue (skeletal muscle, extraocular muscles) - Sensory tissue (retinal tissue, inner ear sensory epithelium)

Specific Cell Populations:

Retinal Cells: - Retinal ganglion cells (RGCs) - primary target (CL:0000740) - Preferential loss in papillomacular bundle

Auditory System: - Inner hair cells (sensory mechanoreceptor cells) - selective loss in Opa1delTTAG mice (affortit2024thehumanopa1delttag pages 1-2) - Spiral ganglion neurons - progressive degeneration of axons and myelin sheaths (affortit2024thehumanopa1delttag pages 1-2) - Outer hair cells - relatively preserved (ANSD phenotype)

Other Cell Types: - Peripheral nerve neurons (sensory and motor neurons) - Skeletal muscle myocytes - Central nervous system neurons (cerebellar, basal ganglia, cortical) - Cardiac myocytes (in cardiomyopathy cases)

Subcellular Level

Cellular Compartments:

Mitochondria (GO:0005739): - Inner mitochondrial membrane (GO:0005743) - OPA1 localization - Mitochondrial cristae - structural abnormalities - Intermembrane space - cytochrome c release - Mitochondrial matrix (GO:0005759)

Other Compartments: - Nucleus - for gene expression changes - Cytoplasm - for fragmented mitochondria - Axons - particularly vulnerable in RGCs due to energy demands

Localization

Anatomical Sites (UBERON Terms):

Ocular: - UBERON:0000970 (eye) - UBERON:0000941 (optic nerve) - UBERON:0000966 (retina) - UBERON:0001789 (optic disc)

Auditory: - UBERON:0001844 (cochlea) - UBERON:0002768 (spiral ganglion)

Nervous System: - UBERON:0000122 (peripheral nervous system) - UBERON:0002037 (cerebellum) - UBERON:0001851 (basal ganglia)

Other: - UBERON:0001134 (skeletal muscle tissue) - UBERON:0000948 (heart)

Lateralization: Bilateral involvement is characteristic for both optic atrophy and hearing loss in DOA Plus (wong2023opa1dominantoptic pages 1-3, kawakita2026frequencyandhearing pages 1-2).

8. Temporal Development

Onset

Age of Onset: Typical onset in the first or second decade of life, often in early childhood for optic atrophy (arruti2023opa1dominantoptic pages 1-2, wong2023opa1dominantoptic pages 1-3). However, expressivity is variable - onset can range from birth to adulthood (sampige2025ittakestwo pages 1-2).

For hearing loss in DOA Plus, onset is typically post-lingual (kawakita2026frequencyandhearing pages 1-2).

Onset Pattern: Insidious, chronic onset for optic atrophy. Visual loss is gradual and progressive rather than acute (wong2023opa1dominantoptic pages 1-3, arruti2023opa1dominantoptic pages 1-2).

Progression

Disease Stages: Formal staging systems were not described in the retrieved evidence. However, progression can be characterized as: - Early: Mild visual impairment, subclinical extra-ocular involvement - Intermediate: Moderate visual loss, emergence of extra-ocular symptoms - Advanced: Severe visual impairment to blindness, multisystem involvement in DOA Plus

Progression Rate: Slow, progressive course. In the 2023 pediatric cohort, mean visual acuity remained unchanged over the follow-up period (0.40 and 0.44 logMAR at baseline and end of study), suggesting stability in some cases, though long-term progression is documented (arruti2023opa1dominantoptic pages 1-2).

Hearing loss in DOA Plus is progressive (kawakita2026frequencyandhearing pages 1-2).

Disease Course Pattern: Progressive (wong2023opa1dominantoptic pages 1-3, arruti2023opa1dominantoptic pages 1-2, kawakita2026frequencyandhearing pages 1-2).

Disease Duration: Chronic, lifelong condition (wong2023opa1dominantoptic pages 1-3).

Patterns

Remission: No spontaneous or treatment-induced remission was documented in the retrieved evidence.

Critical Periods: Early childhood represents a critical period for diagnosis and genetic counseling. Early identification allows for appropriate interventions and family planning (arruti2023opa1dominantoptic pages 1-2).

9. Inheritance and Population

Epidemiology

Prevalence: - General estimates: 1:12,000 to 1:50,000 - Denmark: 1:10,000 (due to founder effect) - North East England: 1:25,000 (wong2023opa1dominantoptic pages 1-3, sampige2025ittakestwo pages 1-2, lee2024hereditaryopticneuropathies pages 1-2)

Incidence: Not systematically reported in the retrieved evidence.

Genetic Inheritance

Inheritance Pattern: Autosomal dominant (wong2023opa1dominantoptic pages 1-3, arruti2023opa1dominantoptic pages 1-2, zeppieri2025isolatedandsyndromic pages 1-2).

Penetrance: Incomplete but high. One study estimated 88% lifetime penetrance for OPA1 mutation carriers (yao2025contrastingpathophysiologicalmechanisms pages 1-2, wong2023opa1dominantoptic pages 1-3).

Expressivity: Markedly variable, both interfamilial and intrafamilial. Visual acuities range from normal to hand movements only. Some carriers remain asymptomatic, while others develop severe multisystem disease (yao2025contrastingpathophysiologicalmechanisms pages 1-2, wong2023opa1dominantoptic pages 1-3, arruti2023opa1dominantoptic pages 1-2).

Genetic Anticipation: Not documented in the retrieved evidence for DOA Plus.

Germline Mosaicism: Not systematically addressed in the retrieved evidence.

Founder Effects: Denmark exhibits a higher prevalence (1:10,000) due to founder effects (sampige2025ittakestwo pages 1-2).

Consanguinity: Not addressed in the retrieved evidence.

Carrier Frequency: Not systematically reported in the retrieved evidence.

Population Demographics

Affected Populations: In the 2026 hearing-loss cohort of 18,475 Japanese patients, 10 individuals from 8 families carried OPA1 variants, suggesting rarity in this population (kawakita2026frequencyandhearing pages 1-2). European populations appear more commonly affected based on prevalence estimates (wong2023opa1dominantoptic pages 1-3, sampige2025ittakestwo pages 1-2).

Geographic Distribution: Higher prevalence in Denmark due to founder effects. Geographic distribution of specific variants was not systematically addressed.

Sex Ratio: Not systematically reported in the retrieved evidence, though one hearing-loss cohort noted 13/14 individuals were male (kawakita2026frequencyandhearing pages 1-2).

Age Distribution: Primarily affects children and young adults, with onset typically in the first or second decade (wong2023opa1dominantoptic pages 1-3, arruti2023opa1dominantoptic pages 1-2).

10. Diagnostics

Clinical Tests

Laboratory Tests: - Serum neurofilament light chain (sNfL): Elevated in DOA and LHON, supporting ongoing neurodegeneration (rufa2025serumneuronalglial pages 1-8) - Serum glial fibrillary acidic protein (sGFAP): Elevated in hereditary optic neuropathies (rufa2025serumneuronalglial pages 1-8) - Serum growth differentiation factor-15 (sGDF-15): Mitochondrial damage marker (rufa2025serumneuronalglial pages 1-8)

Note: These biomarkers are research tools and not yet established as clinical diagnostics.

Biomarkers: No disease-specific biomarkers for DOA Plus are currently in clinical use.

Imaging Studies:

Optical Coherence Tomography (OCT): - Demonstrates RNFL thinning, particularly temporally - Shows ganglion cell layer thinning - Quantifies macular thickness - Essential diagnostic and monitoring tool (wong2023opa1dominantoptic pages 1-3, arruti2023opa1dominantoptic pages 1-2, yao2025contrastingpathophysiologicalmechanisms pages 1-2, rufa2025serumneuronalglial pages 1-8)

OCT Angiography: - Shows reduced blood flow in temporal region of optic disc (wong2023opa1dominantoptic pages 1-3)

Functional Tests:

Visual Field Testing: - Demonstrates central or centrocecal scotomas - Pattern deviation analysis (wong2023opa1dominantoptic pages 1-3, arruti2023opa1dominantoptic pages 1-2)

Visual Acuity Assessment: - Quantifies degree of visual impairment - Monitors progression

Electrophysiology:

Visual Evoked Potentials (VEP): - Assesses functional integrity of optic nerve pathway (zeppieri2025isolatedandsyndromic pages 1-2)

Auditory Tests (for DOA Plus): - Auditory brainstem response (ABR): Abnormal in ANSD - Auditory steady-state response (ASSR): Abnormal in ANSD - Distortion product otoacoustic emissions (DPOAEs): Preserved in ANSD, indicating intact outer hair cell function (kawakita2026frequencyandhearing pages 1-2)

Biopsy/Pathology: Skin fibroblast biopsy for mitochondrial function studies and cell-based modeling (zanfardino2024opa1mutationaffects pages 1-2, yao2025contrastingpathophysiologicalmechanisms pages 1-2).

Genetic Testing

Overview: Molecular genetic testing is essential for definitive diagnosis. Multiple approaches are used:

Whole Exome Sequencing (WES): Identified OPA1 variants in research studies. WES is effective for detecting point mutations and small indels (zhang2025opa1mutationsin pages 1-2, yao2025contrastingpathophysiologicalmechanisms pages 1-2).

Gene Panels: Targeted sequencing of deafness-related genes (158 genes in one study) or hereditary optic neuropathy panels (kawakita2026frequencyandhearing pages 1-2, zeppieri2025isolatedandsyndromic pages 1-2).

Single Gene Testing: Direct sequencing of OPA1 in suspected cases (arruti2023opa1dominantoptic pages 1-2).

Chromosomal Microarray/CNV Analysis: Necessary to detect large deletions encompassing OPA1 (e.g., ~69.86 kb deletion) (yao2025contrastingpathophysiologicalmechanisms pages 1-2).

Sequence/Splice-Site Analysis: Identifies missense, nonsense, frameshift, and splice-site mutations (arruti2023opa1dominantoptic pages 1-2, yao2025contrastingpathophysiologicalmechanisms pages 1-2).

Sanger Sequencing: Used for validation of variants identified by WES or panels (zhang2025opa1mutationsin pages 1-2).

Examples from Evidence: - Pediatric cohort: Identified 7 different OPA1 mutations in 11 children, including one novel variant c.1406_1407del (arruti2023opa1dominantoptic pages 1-2) - 8/11 pediatric patients had positive family history (arruti2023opa1dominantoptic pages 1-2)

Clinical Criteria

Diagnostic Criteria: Diagnosis is based on: 1. Clinical presentation: bilateral optic atrophy, progressive vision loss, characteristic fundus and visual field findings 2. OCT demonstration of RNFL and GCL thinning 3. Molecular genetic confirmation of pathogenic OPA1 variant 4. Family history (often positive but not universal) (wong2023opa1dominantoptic pages 1-3, arruti2023opa1dominantoptic pages 1-2, zeppieri2025isolatedandsyndromic pages 1-2)

Differential Diagnosis: Must distinguish from: - Leber hereditary optic neuropathy (LHON) - acute onset, maternal inheritance, specific mtDNA mutations - Glaucoma - elevated intraocular pressure, different disc appearance - Compressive optic neuropathies - Inflammatory optic neuropathies - Other hereditary optic neuropathies (OPA3, ACO2, WFS1, etc.) (zeppieri2025isolatedandsyndromic pages 1-2, strachan2021theroleof pages 1-2)

Screening

Newborn Screening: Not currently part of standard newborn screening panels.

Carrier Screening: Genetic testing of at-risk family members is recommended for genetic counseling and family planning (arruti2023opa1dominantoptic pages 1-2, sampige2025ittakestwo pages 1-2).

Cascade Screening: Testing of relatives of affected individuals is appropriate (arruti2023opa1dominantoptic pages 1-2).

11. Outcome/Prognosis

Survival and Mortality

Life Expectancy: DOA/DOA Plus is not typically life-limiting, though severe multisystem involvement in DOA Plus could potentially affect lifespan (not systematically quantified in retrieved evidence).

Disease-Specific Mortality: No specific mortality data were reported in the retrieved evidence for DOA Plus.

Morbidity and Function

Morbidity: Visual impairment is the universal morbidity. Half of all DOA patients fail driving standards and are registered as legally blind (wong2023opa1dominantoptic pages 1-3).

DOA Plus adds significant morbidity through: - Hearing impairment requiring rehabilitation - Neurological dysfunction (ataxia, neuropathy) - Muscle weakness - Potential cognitive decline (wong2023opa1dominantoptic pages 1-3, kawakita2026frequencyandhearing pages 1-2)

Disability: Progressive visual disability leads to: - Inability to drive - Occupational limitations - Reduced independence - High rates of psychological distress - Great societal costs (wong2023opa1dominantoptic pages 1-3)

Quality of Life: DOA carries a significant detrimental impact on quality of life. DOA Plus further reduces QOL through multisystem involvement (wong2023opa1dominantoptic pages 1-3, kawakita2026frequencyandhearing pages 1-2).

Disease Course

Complications: - Progressive blindness - Progressive deafness - Neurological deterioration - Muscle atrophy - Cardiac complications (in subset with cardiomyopathy) (wong2023opa1dominantoptic pages 1-3, kawakita2026frequencyandhearing pages 1-2)

Recovery Potential: Visual loss is typically permanent and irreversible. No spontaneous recovery has been documented (wong2023opa1dominantoptic pages 1-3, amore2021therapeuticoptionsin pages 1-2).

Prediction

Prognostic Factors: - Variant type: Missense mutations in GTPase domain associated with more severe phenotypes (DOA Plus) - Age of onset: Earlier onset may correlate with severity - Family history and penetrance (nitta2024drosophilamodelto pages 1-2, wong2023opa1dominantoptic pages 1-3)

Prognostic Biomarkers: Elevated sNfL and sGFAP indicate ongoing neurodegeneration but are not established prognostic tools (rufa2025serumneuronalglial pages 1-8).

12. Treatment

Current Management (Supportive)

Standard of Care: Management remains largely supportive, including: - Low-vision rehabilitation and aids - Visual aids and magnification devices - Genetic counseling for affected individuals and families - Ophthalmologic surveillance with OCT monitoring - Management of extra-ocular complications in DOA Plus (lee2024hereditaryopticneuropathies pages 1-2, wong2023opa1dominantoptic pages 1-3, sampige2025ittakestwo pages 1-2)

Hearing Rehabilitation (DOA Plus): - Hearing aids: Provide limited benefit in ANSD phenotype (5 patients in 2026 cohort had limited benefit) - Cochlear implantation: One patient in 2026 cohort achieved good speech perception (kawakita2026frequencyandhearing pages 1-2)

Pharmacotherapy

Idebenone: - A synthetic short-chain analog of coenzyme Q10 with antioxidant properties - Approved in Europe for LHON in 2015 - For OPA1-related DOA: Preliminary data indicate "possible beneficial effect" but evidence remains limited and not definitive - Off-label/investigational use in DOA - Mechanism: Potent intramitochondrial antioxidant, shuttles electrons directly to complex III, bypassing complex I deficiency (amore2021therapeuticoptionsin pages 1-2, sampige2025ittakestwo pages 1-2, wong2023opa1dominantoptic pages 1-3)

Other Investigational Small Molecules: - Paromomycin: 2025 proof-of-concept study showed rescue of mitochondrial fragmentation induced by c.1034G>A mutation in vitro (yao2025contrastingpathophysiologicalmechanisms pages 1-2) - EPI-743, elamipretide (mtp-131), estrogen-related compounds, rapamycin, miRNA-based therapies: Under investigation for LHON, potential future application to DOA (amore2021therapeuticoptionsin pages 1-2)

Advanced Therapeutics

Gene Therapy:

TANGO (Targeted Augmentation of Nuclear Gene Output): - Novel antisense oligonucleotide approach (STK-002) - Delivered intravitreally - Mechanism: ASO binds to nonsense-mediated decay exons on pre-mRNA transcribed from wild-type OPA1 gene, preserving wild-type gene products - Variant-agnostic approach (addresses haploinsufficiency) - Early-stage development for DOA (sampige2025ittakestwo pages 1-2, wong2023opa1dominantoptic pages 1-3)

Gene Replacement: - Under investigation for DOA - Similar to LHON gene therapy approaches using AAV2 vectors for intravitreal injection - Expected to be developed following LHON precedent (amore2021therapeuticoptionsin pages 1-2, sampige2025ittakestwo pages 1-2)

Gene Editing: - CRISPR-based approaches under investigation - Potential for correcting specific mutations - Preclinical stage (sampige2025ittakestwo pages 1-2)

Metabolic/Mitochondrial Modulators: - Mitochondria-targeted peptides and antioxidants - NAD+ boosters/metabolic support - Mitophagy modulators - Fission-fusion modulators - All investigational, not in clinical use (sampige2025ittakestwo pages 1-2)

Cell-Based Regenerative Therapy: - Stem cell-based approaches for RGC regeneration - Very early stage of investigation - iPSC-derived RGCs provide research tools (sampige2025ittakestwo pages 1-2, dotto2021dominantopticatrophy pages 1-2)

Treatment Outcomes

Response Rates: No established efficacy data for disease-modifying therapies in DOA Plus. Idebenone data primarily from LHON trials (amore2021therapeuticoptionsin pages 1-2).

Adverse Events: Not systematically reported for DOA-specific therapies in the retrieved evidence.

Treatment Strategy

Currently, no treatment algorithms or combination therapy protocols are established for DOA Plus. Management focuses on symptomatic relief and genetic counseling (wong2023opa1dominantoptic pages 1-3, sampige2025ittakestwo pages 1-2).

Suggested MAXO Terms: - MAXO:0000127 (genetic counseling) - MAXO:0000058 (pharmaceutical therapy) - for idebenone - MAXO:0001479 (gene therapy) - investigational - MAXO:0000011 (rehabilitation therapy)

13. Prevention

Primary Prevention

No primary prevention strategies are available for genetically determined DOA Plus.

Secondary Prevention

Screening Programs: Genetic screening of at-risk family members allows for: - Early diagnosis - Anticipatory guidance - Appropriate interventions (e.g., timely hearing aids) - Family planning decisions (arruti2023opa1dominantoptic pages 1-2, sampige2025ittakestwo pages 1-2)

Tertiary Prevention

Management of complications: - Visual rehabilitation to maximize remaining vision - Hearing rehabilitation to optimize communication - Monitoring for neurological/cardiac complications - Occupational therapy for functional adaptation (wong2023opa1dominantoptic pages 1-3, kawakita2026frequencyandhearing pages 1-2)

Genetic Counseling

Counseling: Genetic counseling is essential for: - Risk assessment for family members - Family planning guidance - Discussion of inheritance patterns (autosomal dominant, 88% penetrance, variable expressivity) - Options for prenatal/preimplantation genetic diagnosis (arruti2023opa1dominantoptic pages 1-2, sampige2025ittakestwo pages 1-2, wong2023opa1dominantoptic pages 1-3)

Reproductive Options: Discussed in genetic counseling sessions but not detailed in the retrieved evidence for DOA Plus specifically.

14. Other Species / Natural Disease

Taxonomy

No naturally occurring disease in other species was documented in the retrieved evidence. However, OPA1 orthologs exist across species (see Model Organisms section below).

Zoonotic Potential

Not applicable - DOA Plus is a genetic disease, not infectious.

15. Model Organisms

Model Types and Systems

Yeast Models (Saccharomyces cerevisiae, Schizosaccharomyces pombe): - Orthologs: MGM1 (S. cerevisiae), MSP1 (S. pombe) - Applications: Drug screening (>2,500 drugs tested), functional validation of human OPA1 variants - Chimeric constructs: Mgm1-OPA1 chimeric proteins functionally rescue yeast phenotypes - Validation: OPA1 mutations cause mtDNA loss, mitochondrial fragmentation, reduced respiratory capacity, impaired oxidative growth - Drug discovery: Identified compounds (e.g., 6 drugs) that rescue oxidative growth phenotype and reduce mtDNA instability (dotto2021dominantopticatrophy pages 1-2, strachan2021theroleof pages 1-2)

Drosophila melanogaster (Fruit Fly): - Gene: dOPA1 - 2024 Study: Loss-of-function mutations mimic optic nerve degeneration observed in DOA - Human OPA1 rescue: Expression of human OPA1 rescues dOPA1 mutant phenotype, demonstrating functional conservation - Distinction of mechanisms: Successfully distinguishes loss-of-function from dominant-negative mutations - DOA Plus modeling: DOA Plus mutations suppress wild-type rescue, confirming dominant-negative action - Applications: Guides initial treatment strategies, screens therapeutic approaches (nitta2024drosophilamodelto pages 1-2)

Mouse Models:

Opa1delTTAG Model (2024): - Mutation: Human recurrent OPA1delTTAG mutation - Phenotype: Recapitulates DOA Plus syndrome - Auditory phenotype: Adult-onset progressive auditory neuropathy - >40% reduction in Opa1 mRNA (haploinsufficiency) - Selective loss of sensory inner hair cells - Progressive degeneration of axons and myelin sheaths of spiral ganglion neurons - Age-related mtDNA depletion - Increased oxidative stress - Enhanced mitophagy - Impaired autophagic flux - Applications: Studying mechanisms of OPA1-linked ANSD, testing therapeutic interventions (affortit2024thehumanopa1delttag pages 1-2)

Other Mouse Models: - Various conditional, knockout, and knock-in models referenced but not detailed in the retrieved evidence - Used for studying optic nerve pathology, mitochondrial dynamics, therapeutic testing (dotto2021dominantopticatrophy pages 1-2, strachan2021theroleof pages 1-2)

Patient-Derived iPSC Lines: - 2023 Study: Generated iPSC lines from two DOA patients with distinct OPA1 mutations and clinical pathologies - Applications: Differentiation to RGCs for disease modeling, correlation of cellular phenotypes with clinical features, drug screening - Advantages: Human genetic background, relevant cell type, patient-specific (dotto2021dominantopticatrophy pages 1-2)

Cell Culture Models:

Primary Neurons: - Primary cortical neurons from mice: Assess mitochondrial morphology, membrane potential, cytochrome c release, cell viability - Advantages: Relevant cell type (neurons), appropriate for studying domain-specific mutation effects (zhang2025opa1mutationsin pages 1-2)

Cell Lines: - HeLa cells: Widely used for mitochondrial dynamics studies, transfection with OPA1 constructs - N2a cells (neuroblastoma): Neuronal-like cell line for mechanistic studies - RGC5 cells: Retinal ganglion cell line (though authenticity debated in field) - Patient fibroblasts: Mitochondrial function studies, senescence phenotyping, autophagy assays (zhang2025opa1mutationsin pages 1-2, yao2025contrastingpathophysiologicalmechanisms pages 1-2, zanfardino2024opa1mutationaffects pages 1-2)

Phenotype Recapitulation

Yeast: - Recapitulates: Mitochondrial fragmentation, mtDNA instability, respiratory deficiency - Limitations: Lacks multicellular complexity, optic nerve, neuronal cell types

Drosophila: - Recapitulates: Optic nerve degeneration - Successfully distinguishes haploinsufficiency from dominant-negative mechanisms - Limitations: Invertebrate system, anatomical differences

Mouse: - Recapitulates: Optic atrophy (various models), auditory neuropathy (Opa1delTTAG), mitochondrial dysfunction - Advantages: Mammalian system, relevant anatomy, testable for therapeutics - Limitations: Not all aspects of human DOA Plus captured in single model

iPSCs: - Recapitulates: Patient-specific genetic background, can differentiate to RGCs - Advantages: Human cells, disease-relevant genotype - Limitations: In vitro system, artificial differentiation protocols

Model Limitations

General limitations across models include: - Difficulty fully recapitulating multisystem DOA Plus phenotype in single model - Variable penetrance and expressivity not easily modeled - Long-term disease progression challenging to study in short-lived organisms (dotto2021dominantopticatrophy pages 1-2, strachan2021theroleof pages 1-2)

Research Applications

Models are used for: - Understanding pathogenic mechanisms (fusion, OXPHOS, apoptosis, autophagy) - Distinguishing haploinsufficiency from dominant-negative effects - Screening therapeutic compounds - Testing gene therapy approaches - Studying genotype-phenotype correlations - Developing biomarkers (dotto2021dominantopticatrophy pages 1-2, nitta2024drosophilamodelto pages 1-2, affortit2024thehumanopa1delttag pages 1-2, yao2025contrastingpathophysiologicalmechanisms pages 1-2)

Summary and Conclusions

Autosomal Dominant Optic Atrophy Plus is a multisystem mitochondrial disorder caused primarily by mutations in the OPA1 gene, affecting approximately 20% of OPA1 mutation carriers. The disease extends beyond isolated optic atrophy to include extra-ocular manifestations, most commonly sensorineural hearing loss (often ANSD), peripheral neuropathy, myopathy, ataxia, and neurological complications.

Current understanding emphasizes the dual pathogenic mechanisms of haploinsufficiency (truncating mutations) versus dominant-negative effects (missense mutations in the GTPase domain), which correlate with disease severity. Recent advances (2023-2026) include patient-derived iPSC models, Drosophila functional models distinguishing LOF from dominant-negative mutations, and a mouse model demonstrating progressive auditory neuropathy with detailed mechanistic insights.

While no disease-modifying therapies are currently approved, emerging therapeutic strategies including TANGO antisense oligonucleotides, gene replacement, gene editing, and mitochondrial modulators offer promise. Management currently focuses on supportive care, genetic counseling, and rehabilitation. The prognosis remains guarded, with half of DOA patients experiencing legal blindness and DOA Plus adding substantial morbidity through multisystem involvement.

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