A novel pathogenic variant in TDP2 causes spinocerebellar ataxia autosomal recessive 23 accompanied by pituitary tumor and hyperhidrosis: a case report.

TDP2 gene encodes tyrosyl DNA phosphodiesterase 2, an enzyme required for effective repair of the DNA double-strand breaks (DSBs). Spinocerebellar ataxia autosomal recessive 23 (SCAR23) is a rare disease caused by the pathogenic mutation of TDP2 gene and characterized by intellectual disability, progressive ataxia and refractory epilepsy. Thus far, merely nine patients harboring five different variants (c.425 + 1G > A; c.413_414delinsAA, p. Ser138*; c.400C > T, p. Arg134*; c.636 + 3_ 636 + 6 del; c.4G > T, p. Glu2*) in TDP2 gene have been reported. Here, we describe the tenth patient with a novel variant (c.650del, p. Gly217GlufsTer7) and new phenotype (pituitary tumor and hyperhidrosis).

Anesthetic Management of a Patient With Spinocerebellar Ataxia Type 1.

Spinocerebellar ataxia type 1 (SCA1) is one of the autosomal dominant spinocerebellar degeneration (SCD) diseases characterized by progressive cerebellar ataxia, muscle atrophy, and peripheral neuropathy. We report the management of a 43-year-old man with SCA1 who underwent general anesthesia for open reduction and internal fixation of a mandibular fracture. Although anesthesia-induced vocal cord paralysis has been reported in patients with SCD, nasotracheal intubation was performed uneventfully with video laryngoscope. After taking into consideration the increased risk of postoperative respiratory depression in patients with SCD, rocuronium dosing was titrated carefully, and fentanyl was not used during surgery. Preparation for an anticipated difficult airway and avoiding significant respiratory depression are crucial when providing general anesthesia for patients with SCA1.

Moyamoya associated with Turner syndrome in a patient with type 2 spinocerebellar ataxia-Occam's razor or Hickam's dictum: a case report.

BACKGROUND: Turner syndrome (TS) is a rare condition associated with a completely or partially missing X chromosome that affects 1 in 2500 girls. TS increases the risk of autoimmune diseases, including Graves' disease (GD). Moyamoya disease is a rare cerebral arteriopathy of unknown etiology characterized by progressive bilateral stenosis of the internal carotid artery and its branches. Both TS and GD have been associated with Moyamoya. Type 2 spinocerebellar ataxia (SCA2) is an autosomal dominant cerebellar ataxia caused by a CAG repeat expansion in ATXN2. We present the first case of Moyamoya syndrome in a patient with a previous diagnosis of TS and GD who tested positive for SCA2 and had imaging findings compatible with an overlap of SCA2 and Moyamoya. CASE PRESENTATION: A 43-year-old woman presented with mild gait imbalance for 2 years. Her family history was positive for type 2 spinocerebellar ataxia (SCA2). She had been diagnosed with Turner Syndrome (45,X) and Graves disease three years before. Brain MRI revealed bilateral frontal and parietal cystic encephalomalacia in watershed zones, atrophy of pons, middle cerebellar peduncles and cerebellum. MR angiography showed progressive stenosis of both internal carotid arteries with lenticulostriate collaterals, suggestive of Moya-Moya disease. Molecular analysis confirmed the diagnosis of SCA2. CONCLUSIONS: With increased availability of tools for genetic diagnosis, physicians need to be aware of the possibility of a single patient presenting two or more rare diseases. This report underscores the modern dilemmas created by increasingly accurate imaging techniques and available and extensive genetic testing.

Unravelling the etiology of sporadic late-onset cerebellar ataxia in a cohort of 205 patients: a prospective study.

BACKGROUND: Despite recent progress in the field of genetics, sporadic late-onset (> 40 years) cerebellar ataxia (SLOCA) etiology remains frequently elusive, while the optimal diagnostic workup still needs to be determined. We aimed to comprehensively describe the causes of SLOCA and to discuss the relevance of the investigations. METHODS: We included 205 consecutive patients with SLOCA seen in our referral center. Patients were prospectively investigated using exhaustive clinical assessment, biochemical, genetic, electrophysiological, and imaging explorations. RESULTS: We established a diagnosis in 135 (66%) patients and reported 26 different causes for SLOCA, the most frequent being multiple system atrophy cerebellar type (MSA-C) (41%). Fifty-one patients (25%) had various causes of SLOCA including immune-mediated diseases such as multiple sclerosis or anti-GAD antibody-mediated ataxia; and other causes, such as alcoholic cerebellar degeneration, superficial siderosis, or Creutzfeldt-Jakob disease. We also identified 11 genetic causes in 20 patients, including SPG7 (n = 4), RFC1-associated CANVAS (n = 3), SLC20A2 (n = 3), very-late-onset Friedreich's ataxia (n = 2), FXTAS (n = 2), SCA3 (n = 1), SCA17 (n = 1), DRPLA (n = 1), MYORG (n = 1), MELAS (n = 1), and a mitochondriopathy (n = 1) that were less severe than MSA-C (p < 0.001). Remaining patients (34%) had idiopathic late-onset cerebellar ataxia which was less severe than MSA-C (p < 0.01). CONCLUSION: Our prospective study provides an exhaustive picture of the etiology of SLOCA and clues regarding yield of investigations and diagnostic workup. Based on our observations, we established a diagnostic algorithm for SLOCA.

Characterization of Lifestyle in Spinocerebellar Ataxia Type 3 and Association with Disease Severity.

BACKGROUND: Lifestyle could influence the course of hereditary ataxias, but representative data are missing. OBJECTIVE: The objective of this study was to characterize lifestyle in spinocerebellar ataxia type 3 (SCA3) and investigate possible associations with disease parameters. METHODS: In a prospective cohort study, data on smoking, alcohol consumption, physical activity, physiotherapy, and body mass index (BMI) were collected from 243 patients with SCA3 and 119 controls and tested for associations with age of onset, disease severity, and progression. RESULTS: Compared with controls, patients with SCA3 were less active and consumed less alcohol. Less physical activity and alcohol abstinence were associated with more severe disease, but not with progression rates or age of onset. Smoking, BMI, or physiotherapy did not correlate with disease parameters. CONCLUSION: Differences in lifestyle factors of patients with SCA3 and controls as well as associations of lifestyle factors with disease severity are likely driven by the influence of symptoms on behavior. No association between lifestyle and disease progression was detected. © 2021 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Altered H3 histone acetylation impairs high-fidelity DNA repair to promote cerebellar degeneration in spinocerebellar ataxia type 7.

A common mechanism in inherited ataxia is a vulnerability of DNA damage. Spinocerebellar ataxia type 7 (SCA7) is a CAG-polyglutamine-repeat disorder characterized by cerebellar and retinal degeneration. Polyglutamine-expanded ataxin-7 protein incorporates into STAGA co-activator complex and interferes with transcription by altering histone acetylation. We performed chromatic immunoprecipitation sequencing ChIP-seq on cerebellum from SCA7 mice and observed increased H3K9-promoter acetylation in DNA repair genes, resulting in increased expression. After detecting increased DNA damage in SCA7 cells, mouse primary cerebellar neurons, and patient stem-cell-derived neurons, we documented reduced homology-directed repair (HDR) and single-strand annealing (SSA). To evaluate repair at endogenous DNA in native chromosome context, we modified linear amplification-mediated high-throughput genome-wide translocation sequencing and found that DNA translocations are less frequent in SCA7 models, consistent with decreased HDR and SSA. Altered DNA repair function in SCA7 may predispose the subject to excessive DNA damage, leading to neuron demise and highlights DNA repair as a therapy target.

Nystagmus may be the first neurological sign in early stages of spinocerebellar ataxia type 3 / Nistagmo pode ser o primeiro sinal neurológico nos estágios precoces da ataxia espinocerebelar tipo 3

Abstract Background: Spinocerebellar ataxia type 3 (SCA3) is the most common autosomal dominant spinocerebellar ataxia worldwide. Almost all patients with SCA3 exhibit nystagmus and/or saccades impairment. Objective: To investigate the presence of nystagmus as an early neurological manifestation, before ataxia, in some patients with SCA3 in the first six months of the disease. Methods: We evaluated a series of 155 patients with clinically and molecularly proven SCA3 between 2013 and 2020. Data regarding sex, age, age at onset, disease duration, CAG repeat expansion length, first symptom, presence of ataxia, scores on SARA and ICARS scales, and presence and characteristics of nystagmus were collected. Results: We identified seven patients with symptomatic SCA3 who presented with isolated nystagmus. In these seven individuals the age at onset ranged from 24 to 57 years, and disease duration from four to six months. Conclusions: Our study showed that nystagmus may be the first neurological sign in SCA3. This clinical observation reinforces the idea that the neurodegenerative process in SCA3 patients may start in vestibular system connections or in flocculonodular lobe. This study adds relevant information about pre-symptomatic features in SCA3 that may work as basis for a better understanding of brain degeneration and for future therapeutic clinical trials.

RESUMO Antecedentes: A ataxia espinocerebelar tipo 3 (SCA3) é a ataxia espinocerebelar de herança autossômica dominante mais comum em todo o mundo. Quase todos os pacientes com SCA3 têm nistagmo e/ou comprometimento das sácades. Objetivo: Investigar a presença de nistagmo como manifestação neurológica precoce, antes do surgimento da ataxia, em alguns pacientes com SCA3 nos primeiros seis meses de doença. Métodos: Foram avaliados 155 pacientes com diagnóstico clínico e molecular de SCA3, entre 2013 e 2020, em relação a sexo, idade, idade de início, duração da doença, expansão da repetição CAG, primeiro sintoma, presença de ataxia, pontuações nas escalas SARA e ICARS, e presença e caracterização de nistagmo. Resultados: Identificamos sete pacientes com SCA3 que apresentavam nistagmo isolado. A idade de início da doença nesses pacientes variou de 24 a 57 anos e a duração da doença variou de quatro a seis meses. Conclusões: O nosso estudo mostrou que o nistagmo pode ser o primeiro sinal neurológico na SCA3. Essa observação clínica reforça a ideia de que o processo neurodegenerativo nos pacientes com SCA3 pode se iniciar nas conexões do sistema vestibular ou no lobo floculonodular. Este estudo adiciona informações relevantes sobre características pré-sintomáticas na SCA3 e que podem servir de base para melhor entendimento da degeneração cerebral e para futuras terapias.

Mood alterations in mouse models of Spinocerebellar Ataxia type 1.

Spinocerebellar ataxia type 1 (SCA1) is a fatal neurodegenerative disease caused by abnormal expansion of glutamine-encoding CAG repeats in the Ataxin-1 (ATXN1) gene. SCA1 is characterized by progressive motor deficits, cognitive decline, and mood changes including anxiety and depression, with longer number of repeats correlating with worse disease outcomes. While mouse models have been very useful in understanding etiology of ataxia and cognitive decline, our understanding of mood symptoms in SCA1 has lagged. It remains unclear whether anxiety or depression stem from an underlying brain pathology or as a consequence of living with an untreatable and lethal disease. To increase our understanding of the etiology of SCA1 mood alterations, we used the elevated-plus maze, sucrose preference and forced swim tests to assess mood in four different mouse lines. We found that SCA1 knock-in mice exhibit increased anxiety that correlated with the length of CAG repeats, supporting the idea that underlying brain pathology contributes to SCA1-like anxiety. Additionally, our results support the concept that increased anxiety is caused by non-cerebellar pathology, as Purkinje cell specific SCA1 transgenic mice exhibit decreased anxiety-like behavior. Regarding the molecular mechanism, partial loss of ATXN1 may play a role in anxiety, based on our results for Atxn1 haploinsufficient and null mice.

Inclusion body myositis in patients with spinocerebellar ataxia types 3 and 6.

OBJECTIVES: To describe the combination of spinocerebellar ataxia (SCA) types 3 and 6 and sporadic inclusion body myositis (IBM). METHODS: A description of five patients with SCA type 3 and 6 who were diagnosed with IBM. We explore possible mechanisms explaining the coexistence of both diseases. RESULTS: The patients with SCA-3 (n=4) and SCA-6 (n=1) developed asymmetric muscle weakness in a pattern suggestive of IBM in the course of their disease. Based on findings of neurological examination and additional investigations (muscle ultrasound, muscle biopsy), the diagnosis of IBM was made in all patients. CONCLUSION: We report on five patients with concomitant SCA and IBM. Our cases may merely illustrate coincidental co-occurrence of IBM and SCA-3/SCA-6. However, the presence of SCA mutations could predispose to the development of IBM in some SCA patients, or, the presence of toxic aggregates and malfunctioning of cellular quality control processes in both diseases could indicate a convergence of disease mechanisms.

Urinary Symptoms and Urodynamic Findings in Patients with Spinocerebellar Ataxia.

Urinary dysfunctions are not considered symptoms of spinocerebellar ataxias (SCAs). However, given that a patient with SCAs without a family history might be misdiagnosed as MSA-C when having urinary dysfunctions, characterization of urinary dysfunctions in SCAs is needed not only to understand SCAs but also to correctly diagnosis patients with ataxia. We retrospectively reviewed medical records of 143 patients with genetically confirmed SCA1, 2, 3, 6, 7, 17, and DRPLA. Twenty-two patients (men n = 9; age 62.1 ± 10.9; disease duration 8.2 ± 2.9 years) who had lower urinary track symptoms (LUTS) were included in this study. Six patients underwent urodynamic study (UDS), and 2 underwent uroflowmetry. LUTS was present in 1 of 11 patients with SCA1, in 4 of 51 with SCA2, in 2 of 26 with SCA3, in 3 of 20 with SCA6, in 2 of 4 with SCA7, in 8 of 26 with SCA17, and in 2 of 5 with DRPLA. Overall, urinary frequency was the most common symptom (16 patients, 72.7%) followed by voiding difficulty. In three of the 6 patients with UDS, post-micturition residuals were > 100 ml. Detrusor overactivity was noted in three patients. Detrusor areflexia was observed in one. Four patients were diagnosed with a neurogenic bladder, 3 with a storage problem, and 1 with both storage and voiding problems. Fifteen percent of the patients with SCAs had LUTS, and LUTS occurred in various types of SCAs. Our results indicate that SCAs should be considered in patients with progressive cerebellar ataxia and urinary dysfunctions.

Pure-Tone Hearing Thresholds and Brainstem Auditory Evoked Potentials in Sporadic Ataxia

Abstract Introduction Spinocerebellar ataxia (SCA) is part of a genetic and clinical heteroge- neous group of neurodegenerative diseases characterized by progressive cerebellar ataxia. Objective To describe the results of audiological and electrophysiological hearing evaluations in patients with sporadic ataxia (SA). Methods A retrospective cross-sectional study was carried out with 11 patients submitted to the following procedures: anamnesis, otorhinolaryngological evaluation, tonal and vocal audiometry, acoustic immittance and brainstem auditory evoked potential (BAEP) tests. Results The patients presented with a prevalence of gait imbalance, of dysarthria, and of dysphagia; in the audiometric and BAEPs, four patients presented with alterations; in the acoustic immittance test, five patients presented with alterations, predominantly bilateral. Conclusion The most evident alterations in the audiological evaluation were the prevalence of the descending audiometric configuration between the frequencies of 2 and 4 kHz and the absence of the acoustic reflex between the frequencies of 3 and 4 kHz bilaterally. In the electrophysiological evaluation, the patients presented changes with a prevalence of increased I, III and V wave latencies and the interval in the interpeak I-III, I-V and III-V. In the present study, it was observed that auditory complaints did not have a significant prevalence in this type of ataxia, which does not occur in some types of autosomal recessive and dominant ataxia.

Obsessive-compulsive disorder in a patient with SCA type 1 / Transtorno obsessivo compulsivo em um paciente com SCA tipo 1

For many years, the cerebellum was thought to be only responsible for balance, movement, planning and execution. Nowadays, it is well accepted that most cerebellar connections are involved in non-motor functions. Herein, we provide a case report in which a 27-year-old Brazilian male, diagnosed with Obsessive-Compulsive Disorder (OCD), has demonstrated cerebellar features that could be connected to Spinocerebellar ataxia type 1 (SCA-1), an autosomal dominant polyglutamine neurodegenerative disorder that had been previously ruled out. Since obsessive compulsive symptoms (OCS) are known to correlate with alterations in the cortico-striato-thalamo-cortical circuitry, we propose a possible association between OCS and SCA onset.

Durante muitos anos, o cerebelo foi considerado responsável exclusivamente pelo controle das funções de equilíbrio, movimento, planejamento e execução. Atualmente, já está consagrada a participação das conexões cerebelares em funções não-motoras. Apresentamos um relato de caso de um paciente de 27 anos de idade, diagnosticado com Transtorno Obsessivo-Compulsivo (TOC). O paciente apresentava sintomas cerebelares compatíveis com o diagnóstico de ataxia espinocerebelar tipo 1 (SCA-1), um distúrbio da poliglutamina, autossômico dominante neurodegenerativo, que havia sido previamente descartado. Como os sintomas obsessivos compulsivos (SOC) são conhecidos por correlacionar-se com alterações nos circuitos cortico-estriato-tálamo-cortical, propomos uma possível associação entre o SOC e o início da SCA.

Surgical Responses and Outcomes of Bilateral Medial Rectus Recession in Esotropia With Spinocerebellar Ataxia.

PURPOSE: To evaluate the surgical responses and outcomes of bilateral medial rectus (BMR) recession in esotropic patients with spinocerebellar ataxia (SCA) and to compare the results with normal controls. METHODS: The medical records of patients with SCA who underwent strabismus surgery for esotropia between 2006 and 2015 were reviewed retrospectively. Five esotropic patients with SCA (SCA group) and 10 esotropic patients without neurologic disorders (control group) who underwent BMR recession were included. Success rates, surgical responses, and the amount of preoperative and postoperative distance-near disparity were evaluated and compared between the groups. RESULTS: The mean preoperative esodeviation was not different between the SCA and control groups (20 vs 17.3 prism diopters [PD], P = .214). However, patients with SCA showed significant undercorrection compared with controls 1 week postoperatively (4.8 vs 1.0 PD, P = .048) and at the final follow-up (6.8 vs 1.8 PD, P = .032). The surgical success rates for the SCA and control groups were 40% and 80%, respectively (P = .095). Patients with SCA demonstrated a significantly reduced surgical response compared with controls (3.15 vs 3.87 PD/mm, P = .004), and a greater amount of postoperative distance-near disparity than controls (8.0 vs 1.1 PD, P = .001). CONCLUSIONS: A significant undercorrection was observed following BMR recession in esotropic patients with SCA. Accordingly, the authors recommend a slight overcorrection of 5 to 10 PD or adding a slanting procedure when planning strabismus surgery for this distinct group of patients. [J Pediatr Ophthalmol Strabismus. 2019;56(4):266-270.].

Airway Obstruction Caused by Mucinous Material Adherent to the Epiglottis in a Patient with a Progressive Neurological Disorder: An Unusual Case of a Condition Mimicking Acquired Laryngomalacia.

We herein report the successful management of a condition mimicking acquired laryngomalacia using conservative methods in an elderly man with a progressive neurological disorder. The patient developed stridor and was transferred to the intensive-care unit. Flexible laryngoscopy revealed a collapsed epiglottis during inspiration, as seen in acquired laryngomalacia, with mucinous material firmly adhered to the epiglottis. The stridor resolved after the removal of this material. Pathology revealed keratinized material, suggesting a collection of sputum or epithelial tissue. Thus, flexible laryngoscopy can differentiate the cause of airway obstruction and avoid unnecessary endotracheal intubation in patients with neurological disorders.

Recurrent postoperative delirium in spinocerebellar ataxia type 2: a case report.

BACKGROUND: Postoperative delirium is a relatively uncommon condition in middle aged patients, but very widespread in patients with psychiatric and neurological diseases undergoing general anesthesia. Few studies are currently available in the literature on the perioperative anesthesiological management of patients suffering from spinocerebellar ataxia. CASE PRESENTATION: A 58-year-old Caucasian woman affected by spinocerebellar ataxia type 2 underwent total hip arthroplasty for advanced osteoarthritis. One month later, debridement, antibiotics, and implant retention was performed for periprosthetic hip infection. Both times she underwent general anesthesia and developed an early postoperative delirium treated successfully with chlorpromazine. CONCLUSIONS: This case report highlights the need to correctly manage patients at high risk of developing postoperative delirium, especially if suffering from degenerative neurological diseases. On the other hand, further studies will be needed in order to evaluate if spinocerebellar ataxia is an independent risk factor for the development of this acute and transient pathological condition.

Cell Death Mechanisms in a Mouse Model of Retinal Degeneration in Spinocerebellar Ataxia 7.

Spino-cerebellar ataxia type 7 (SCA7) is a polyglutamine (polyQ) disorder characterized by neurodegeneration of the brain, cerebellum, and retina caused by a polyglutamine expansion in ataxin7. The presence of an expanded polyQ tract in a mutant protein is known to induce protein aggregation, cellular stress, toxicity, and finally cell death. However, the consequences of the presence of mutant ataxin7 in the retina and the mechanisms underlying photoreceptor degeneration remain poorly understood. In this study, we show that in a retinal SCA7 mouse model, polyQ ataxin7 induces stress within the retina and activates Muller cells. Moreover, unfolded protein response and autophagy are activated in SCA7 photoreceptors. We have also shown that the photoreceptor death does not involve a caspase-dependent apoptosis but instead involves apoptosis inducing factor (AIF) and Leukocyte Elastase Inhibitor (LEI/L-DNase II). When these two cell death effectors are downregulated by their siRNA, a significant reduction in photoreceptor death is observed. These results highlight the consequences of polyQ protein expression in the retina and the role of caspase-independent pathways involved in photoreceptor cell death.

Antisense oligonucleotides targeting mutant Ataxin-7 restore visual function in a mouse model of spinocerebellar ataxia type 7.

Spinocerebellar ataxia type 7 (SCA7) is an autosomal dominant neurodegenerative disorder characterized by cerebellar and retinal degeneration, and is caused by a CAG-polyglutamine repeat expansion in the ATAXIN-7 gene. Patients with SCA7 develop progressive cone-rod dystrophy, typically resulting in blindness. Antisense oligonucleotides (ASOs) are single-stranded chemically modified nucleic acids designed to mediate the destruction, prevent the translation, or modify the processing of targeted RNAs. Here, we evaluated ASOs as treatments for SCA7 retinal degeneration in representative mouse models of the disease after injection into the vitreous humor of the eye. Using Ataxin-7 aggregation, visual function, retinal histopathology, gene expression, and epigenetic dysregulation as outcome measures, we found that ASO-mediated Ataxin-7 knockdown yielded improvements in treated SCA7 mice. In SCA7 mice with retinal disease, intravitreal injection of Ataxin-7 ASOs also improved visual function despite initiating treatment after symptom onset. Using color fundus photography and autofluorescence imaging, we also determined the nature of retinal degeneration in human SCA7 patients. We observed variable disease severity and cataloged rapidly progressive retinal degeneration. Given the accessibility of neural retina, availability of objective, quantitative readouts for monitoring therapeutic response, and the rapid disease progression in SCA7, ASOs targeting ATAXIN-7 might represent a viable treatment for SCA7 retinal degeneration.

Mutations in COA7 cause spinocerebellar ataxia with axonal neuropathy.

Several genes related to mitochondrial functions have been identified as causative genes of neuropathy or ataxia. Cytochrome c oxidase assembly factor 7 (COA7) may have a role in assembling mitochondrial respiratory chain complexes that function in oxidative phosphorylation. Here we identified four unrelated patients with recessive mutations in COA7 among a Japanese case series of 1396 patients with Charcot-Marie-Tooth disease (CMT) or other inherited peripheral neuropathies, including complex forms of CMT. We also found that all four patients had characteristic neurological features of peripheral neuropathy and ataxia with cerebellar atrophy, and some patients showed leukoencephalopathy or spinal cord atrophy on MRI scans. Validated mutations were located at highly conserved residues among different species and segregated with the disease in each family. Nerve conduction studies showed axonal sensorimotor neuropathy. Sural nerve biopsies showed chronic axonal degeneration with a marked loss of large and medium myelinated fibres. An immunohistochemical assay with an anti-COA7 antibody in the sural nerve from the control patient showed the positive expression of COA7 in the cytoplasm of Schwann cells. We also observed mildly elevated serum creatine kinase levels in all patients and the presence of a few ragged-red fibres and some cytochrome c oxidase-negative fibres in a muscle biopsy obtained from one patient, which was suggestive of subclinical mitochondrial myopathy. Mitochondrial respiratory chain enzyme assay in skin fibroblasts from the three patients showed a definitive decrease in complex I or complex IV. Immunocytochemical analysis of subcellular localization in HeLa cells indicated that mutant COA7 proteins as well as wild-type COA7 were localized in mitochondria, which suggests that mutant COA7 does not affect the mitochondrial recruitment and may affect the stability or localization of COA7 interaction partners in the mitochondria. In addition, Drosophila COA7 (dCOA7) knockdown models showed rough eye phenotype, reduced lifespan, impaired locomotive ability and shortened synaptic branches of motor neurons. Our results suggest that loss-of-function COA7 mutation is responsible for the phenotype of the presented patients, and this new entity of disease would be referred to as spinocerebellar ataxia with axonal neuropathy type 3.