RARE DISEASE
Spinocerebellar ataxia type 3
Spinocerebellar ataxia type 3
Spinocerebellar ataxia type 3
Synonyms: Azorean disease of the nervous system, MJD, Machado disease, Machado-Joseph disease, Nigro-spino-dentatal degeneration with nuclear ophthalmoplegia, SCA3
Synonyms: Azorean disease of the nervous system, MJD, Machado disease, Machado-Joseph disease, Nigro-spino-dentatal degeneration with nuclear ophthalmoplegia, SCA3
Synonyms: Azorean disease of the nervous system, MJD, Machado disease, Machado-Joseph disease, Nigro-spino-dentatal degeneration with nuclear ophthalmoplegia, SCA3
Drug discovery
1
drug
With orphan designation
Overview
Spinocerebellar Ataxia Type 3 (SCA3/MJD) is an autosomal dominant neurodegenerative disorder caused by a CAG repeat expansion in the ATXN3 gene, producing toxic polyglutamine aggregates. It manifests with progressive cerebellar ataxia, dysarthria, pyramidal signs, oculomotor abnormalities, and peripheral neuropathy. Non-motor features include sleep disorders (REM sleep behavior disorder), neuropathic pain, and psychiatric comorbidities. Symptom onset typically occurs in adulthood (2nd–5th decade), with progressive disability leading to wheelchair dependence within 10–20 years. Anticipation correlates with longer CAG repeats [1][6][16].
Therapies
Symptomatic management: Pharmacotherapy for spasticity (baclofen), Parkinsonism (levodopa), and neuropathic pain (antidepressants) [6][8]
Rehabilitative support: Physical/occupational therapy to maintain mobility; speech therapy for dysphagia/dysarthria [18][20]
Experimental approaches: Antisense oligonucleotides, CRISPR-based gene silencing, and HDAC inhibitors in clinical trials [3][13][16]
Categories: rare genetic diseases, rare neurological diseases
Research Papers
677 drug discovery papers related to Spinocerebellar ataxia type 3, with 6 first-in-class and 3 next-in-class early-stage therapies forecasted to outperform the average preclinical success rate. Recent publications:
677 drug discovery papers related to Spinocerebellar ataxia type 3, with 6 first-in-class and 3 next-in-class early-stage therapies forecasted to outperform the average preclinical success rate. Recent publications:
2026-07-06 | Mapping the Disrupted Connectome in Spinocerebellar Ataxia Type 3: A Network-Based Statistics Study Identifying Novel Therapeutic Targets for Neuromodulation.
Spinocerebellar ataxia type 3 (SCA3) is characterized by progressive neurodegeneration. This study aimed to map alterations in structural and functional connectivity (SC and FC) in SCA3 using network-based statistics (NBS) and to explore the potential of transcranial magnetic stimulation (TMS) for modulating these aberrant networks and identifying novel therapeutic targets. NBS was used to compare SC and FC between a large cohort of 117 SCA3 patients and 163 healthy controls (HCs). Partial correlation analysis examined the associations between altered connectivity and clinical variables (CAG repeat length, disease duration, and clinical scale scores). Additionally, paired t-tests were used to evaluate longitudinal brain connectivity changes in 58 patients before and after TMS intervention to assess therapeutic effects. SCA3 patients exhibited a distinct disconnection-compensation pattern, characterized by significantly reduced SC and elevated FC within the subcortical (SUB), sensorimotor (SMN), and dorsal attention (DAN) networks. SC between the frontoparietal network (FPN) and SUB was abnormally increased and positively correlated with both disease duration and CAG repeat length, whereas intra-SUB SC was negatively correlated with disease duration. Following TMS intervention, SC strength in two pathways that were abnormally enhanced at baseline was significantly attenuated. Our findings reveal extensive connectome reorganization in SCA3. The correlations between SC abnormalities and clinical metrics, coupled with the modulatory effects of TMS, suggest that network-based metrics can serve as biomarkers and guide the development of personalized neuromodulation strategies for SCA3. (ChiCTR) 1800019901, 2000039434, 2500095738.
2026-07-02 | Adipose-Derived Mesenchymal Stem Cells Improve Motor Function and Reduce Neuroinflammation and Mutant Ataxin-3 Protein Levels in SCA3 Mice.
The CAG expansion in the ataxin-3 (ATXN3) protein is the underlying cause of Spinocerebellar Ataxia Type 3 (SCA3), a polyglutamine disease. The aggregation of mutant ATXN3 protein is hypothesized to contribute to neuronal dysfunction, neurodegeneration, or neuroinflammation. Mesenchymal stem cells have pleiotropic therapeutic properties, and adipose-derived mesenchymal stem cells (ADMSC) have been shown to be safe and well-tolerated in SCA3 patients. In this study, we evaluated the therapeutic effects of ADMSC in SCA3 mice. In a mouse model of SCA3, the Purkinje-cell-specific L7 promoter drives the expression of a truncated form of human ataxin-3 with 69 glutamine repeats. SCA3 mice exhibited cerebellar Purkinje cell degeneration, reduced myelination, and increased gliosis; pathological features also observed in SCA3 patients. SCA3 mice received repeated intravenous administrations of ADMSC, and efficacy was assessed by rotarod performance, molecular and pathological changes, and serum neurofilament light chain (NfL) levels. ADMSC-treated SCA3 mice showed significant improvements in rotarod performance, a reduction in accumulated toxic mutant ATXN3-69Q protein in Purkinje cells, decreased demyelination, and alleviation of neuroinflammatory and systemic inflammatory responses during disease progression. Furthermore, NfL levels, a potential biomarker for SCA3 disease progression, were inversely correlated with the rotarod performance. Based on these findings, we conclude that ADMSC enhance motor function in SCA3 mice by reducing neuroinflammation, demyelination and aggregated mutant ataxin-3 protein levels in Purkinje cells. ADMSC have the potential to serve as a disease-modifying therapy for SCA3 patients.
2026-06-09 | First-Person Physiology Reveals a Tunable Redox State Transition that Stabilizes Neuroaxonal Injury in SCA3
Spinocerebellar ataxia type 3 (SCA3) is a fatal monogenic neurodegenerative disease with no disease-modifying therapies. Progressive disorders of this kind expose a fundamental mismatch: static clinical trial designs are poorly suited to capturing or redirecting dynamic, system-level pathophysiology. This mismatch may be especially important before overt structural injury, during a biochemical prodrome—a measurable phase of homeostatic erosion that precedes irreversible decline. Here, in a first-person, survival-driven N-of-1 investigation, we applied a closed-loop, four-pillar metabolic intervention—coupling redox stabilization, mitochondrial flux support, methylation control, and proteostasis clearance—to test whether this upstream window could be experimentally engaged. By resolving a kinetic bottleneck in glutathione recycling through real-time biomarker-guided titration, we observed a quantifiable transition in redox physiology, marked by collapse of intracellular reactive oxygen species from a pathological bimodal to a physiological unimodal distribution. This upstream metabolic reconfiguration was followed by sustained stabilization of serum neurofilament light chain over fourteen months despite the withdrawal of all symptomatic medications. Together, these findings support the interpretation that, in this individual, neuroaxonal injury became partially constrained by a modifiable metabolic state despite persistence of the causal mutation. More broadly, the study suggests that clinical phenotype in monogenic neurodegeneration may reflect not genotype alone, but the dynamic resilience of the metabolic system through which it is expressed—and that a coupled multi-pillar intervention, by restoring bioenergetic infrastructure before engaging proteostatic clearance, can functionally navigate a genetic lesion previously framed as largely genotype-determined.
2026-07-06 | Mapping the Disrupted Connectome in Spinocerebellar Ataxia Type 3: A Network-Based Statistics Study Identifying Novel Therapeutic Targets for Neuromodulation.
Spinocerebellar ataxia type 3 (SCA3) is characterized by progressive neurodegeneration. This study aimed to map alterations in structural and functional connectivity (SC and FC) in SCA3 using network-based statistics (NBS) and to explore the potential of transcranial magnetic stimulation (TMS) for modulating these aberrant networks and identifying novel therapeutic targets. NBS was used to compare SC and FC between a large cohort of 117 SCA3 patients and 163 healthy controls (HCs). Partial correlation analysis examined the associations between altered connectivity and clinical variables (CAG repeat length, disease duration, and clinical scale scores). Additionally, paired t-tests were used to evaluate longitudinal brain connectivity changes in 58 patients before and after TMS intervention to assess therapeutic effects. SCA3 patients exhibited a distinct disconnection-compensation pattern, characterized by significantly reduced SC and elevated FC within the subcortical (SUB), sensorimotor (SMN), and dorsal attention (DAN) networks. SC between the frontoparietal network (FPN) and SUB was abnormally increased and positively correlated with both disease duration and CAG repeat length, whereas intra-SUB SC was negatively correlated with disease duration. Following TMS intervention, SC strength in two pathways that were abnormally enhanced at baseline was significantly attenuated. Our findings reveal extensive connectome reorganization in SCA3. The correlations between SC abnormalities and clinical metrics, coupled with the modulatory effects of TMS, suggest that network-based metrics can serve as biomarkers and guide the development of personalized neuromodulation strategies for SCA3. (ChiCTR) 1800019901, 2000039434, 2500095738.
2026-07-02 | Adipose-Derived Mesenchymal Stem Cells Improve Motor Function and Reduce Neuroinflammation and Mutant Ataxin-3 Protein Levels in SCA3 Mice.
The CAG expansion in the ataxin-3 (ATXN3) protein is the underlying cause of Spinocerebellar Ataxia Type 3 (SCA3), a polyglutamine disease. The aggregation of mutant ATXN3 protein is hypothesized to contribute to neuronal dysfunction, neurodegeneration, or neuroinflammation. Mesenchymal stem cells have pleiotropic therapeutic properties, and adipose-derived mesenchymal stem cells (ADMSC) have been shown to be safe and well-tolerated in SCA3 patients. In this study, we evaluated the therapeutic effects of ADMSC in SCA3 mice. In a mouse model of SCA3, the Purkinje-cell-specific L7 promoter drives the expression of a truncated form of human ataxin-3 with 69 glutamine repeats. SCA3 mice exhibited cerebellar Purkinje cell degeneration, reduced myelination, and increased gliosis; pathological features also observed in SCA3 patients. SCA3 mice received repeated intravenous administrations of ADMSC, and efficacy was assessed by rotarod performance, molecular and pathological changes, and serum neurofilament light chain (NfL) levels. ADMSC-treated SCA3 mice showed significant improvements in rotarod performance, a reduction in accumulated toxic mutant ATXN3-69Q protein in Purkinje cells, decreased demyelination, and alleviation of neuroinflammatory and systemic inflammatory responses during disease progression. Furthermore, NfL levels, a potential biomarker for SCA3 disease progression, were inversely correlated with the rotarod performance. Based on these findings, we conclude that ADMSC enhance motor function in SCA3 mice by reducing neuroinflammation, demyelination and aggregated mutant ataxin-3 protein levels in Purkinje cells. ADMSC have the potential to serve as a disease-modifying therapy for SCA3 patients.
2026-06-09 | First-Person Physiology Reveals a Tunable Redox State Transition that Stabilizes Neuroaxonal Injury in SCA3
Spinocerebellar ataxia type 3 (SCA3) is a fatal monogenic neurodegenerative disease with no disease-modifying therapies. Progressive disorders of this kind expose a fundamental mismatch: static clinical trial designs are poorly suited to capturing or redirecting dynamic, system-level pathophysiology. This mismatch may be especially important before overt structural injury, during a biochemical prodrome—a measurable phase of homeostatic erosion that precedes irreversible decline. Here, in a first-person, survival-driven N-of-1 investigation, we applied a closed-loop, four-pillar metabolic intervention—coupling redox stabilization, mitochondrial flux support, methylation control, and proteostasis clearance—to test whether this upstream window could be experimentally engaged. By resolving a kinetic bottleneck in glutathione recycling through real-time biomarker-guided titration, we observed a quantifiable transition in redox physiology, marked by collapse of intracellular reactive oxygen species from a pathological bimodal to a physiological unimodal distribution. This upstream metabolic reconfiguration was followed by sustained stabilization of serum neurofilament light chain over fourteen months despite the withdrawal of all symptomatic medications. Together, these findings support the interpretation that, in this individual, neuroaxonal injury became partially constrained by a modifiable metabolic state despite persistence of the causal mutation. More broadly, the study suggests that clinical phenotype in monogenic neurodegeneration may reflect not genotype alone, but the dynamic resilience of the metabolic system through which it is expressed—and that a coupled multi-pillar intervention, by restoring bioenergetic infrastructure before engaging proteostatic clearance, can functionally navigate a genetic lesion previously framed as largely genotype-determined.
Access all drug discovery articles and probability of success in trials forecasts:
Access all drug discovery articles and probability of success in trials forecasts:
Drug Discovery Landscape
1 orphan drug designation for Spinocerebellar ataxia type 3.
1 orphan drug designation for Spinocerebellar ataxia type 3.
Drug | Therapy type | Regulator | Orphan designation | Approval | Sponsor |
|---|---|---|---|---|---|
trehalose | small molecules | FDA | 2014-11-17 | — | Seelos Therapeutics, Inc. |
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