RARE DISEASE
Spastic paraplegia type 7
Spastic paraplegia type 7
Spastic paraplegia type 7
Synonyms: SPG7
Synonyms: SPG7
Synonyms: SPG7
Drug discovery
0
drugs
With orphan designations
Overview
Spastic Paraplegia Type 7 (SPG7) is an autosomal recessive neurodegenerative disorder caused by biallelic SPG7 mutations, leading to progressive lower-limb spasticity, cerebellar ataxia, and frequent extraspinal features (optic atrophy, dysarthria, dysphagia, parkinsonism). Onset is typically in adulthood (10–72 years), with multisystem involvement including mitochondrial dysfunction. Diagnosis relies on genetic testing, and management focuses on symptom relief.
Burden
Therapies
Symptomatic: Oral/intrathecal baclofen, botulinum toxin, antispasmodics (tizanidine), and physical/occupational therapy [1][2][12].
Supportive: Management of bladder dysfunction (oxybutynin), parkinsonism (levodopa), and dysphagia [1][8][12].
Emerging: Targeted genomic therapies (antisense oligonucleotides, gene replacement) in preclinical stages [3][16].
Categories: rare genetic diseases, rare inborn errors of metabolism, rare neurological diseases, rare ophthalmic disorders
Research Papers
37 drug discovery papers about Spastic paraplegia type 7, with 2 first-in-class emerging drug candidates forecasted to outperform the average preclinical success rate. Recent publications:
37 drug discovery papers about Spastic paraplegia type 7, with 2 first-in-class emerging drug candidates forecasted to outperform the average preclinical success rate. Recent publications:
2026-06-30 | Berberine improves motor deficits in the spastic paraplegia SPG7 mutant mice
Abstract Hereditary spastic paraplegia type 7 (SPG7) is a neurodegenerative disorder characterized by progressive motor impairment and cerebellar dysfunction. Mutations in the SPG7 gene, encoding the mitochondrial metalloprotease paraplegin, disrupt mitochondrial homeostasis and lead to neuronal vulnerability and deficits in motor coordination. Recent studies have identified defective flickering of the mitochondrial permeability transition pore (mPTP) in SPG7 models, suggesting that altered pore dynamics may represent a functional biomarker of mitochondrial dysfunction. Here, we investigated whether pharmacological modulation of mPTP activity could improve mitochondrial function and motor performance in SPG7 models. Mitochondrial flickering was assessed in vitro , while motor behavior was evaluated in vivo following chronic treatment with berberine, a natural isoquinoline alkaloid known to modulate mitochondrial bioenergetics. Spg7 −/− mice and age-matched Spg7 +/ littermate controls received daily oral berberine administration for several weeks, and motor coordination was assessed using the accelerating rotarod test. Untreated Spg7 −/− mice exhibited reduced rotarod performance compared with controls, indicating impaired motor coordination. Berberine treatment significantly improved motor performance in pre-symptomatic mutant mice. These findings indicate that pharmacological modulation of mitochondrial permeability transition pore dynamics can ameliorate motor dysfunction associated with SPG7 deficiency and highlight mPTP flickering as a functional readout of mitochondrial health.
2026-06-29 | Rescue of mitochondrial and neurite pathology in SPG7 hereditary spastic paraplegia patient-derived cortical neurons.
Biallelic pathogenic variants in SPG7 are a frequent cause of hereditary spastic paraplegia leading to progressive disability due to a length-dependent degeneration of cerebellar and cortical projection neurons. While underlying mechanisms have been linked to impaired mitochondrial function, no disease-modifying therapy is available. We generated induced pluripotent stem cell-derived cortical neurons from SPG7 patients with non-sense or truncating variants and from matched controls. We performed detailed phenotyping of neuronal differentiation, as well as mitochondrial and neuritic morphology and function. We explored the effects of Bz-423, a modulator of the mitochondrial permeability transition pore, as a potential rescue of SPG7-specific cellular phenotypes. We successfully differentiated SPG7 patient-derived neurons, without quantitative differences in differentiation compared with controls. However, we delineate neurite-specific aberrations of mitochondrial morphology and ultrastructure. Moreover, anterograde axonal mitochondrial transport was impaired in SPG7. Exposure to Bz-423 rescued ultrastructural and functional phenotypes. In summary, our data show impaired neuritic mitochondria in a patient-specific human model, and we here demonstrate for the first time beneficial effects of Bz-423 on neuritic ultrastructure and function in a human neuronal SPG7 system. Moreover, we identify the mitochondrial permeability transition pore as a molecular target to rescue phenotypes also in carriers of non-sense or truncating SPG7 variants.
2026-05-12 | Expanding the genetic and clinical landscapes of hereditary spastic paraplegia (HSP): a cohort study of 103 families
Abstract Background Hereditary spastic paraplegia (HSP) refers to a heterogeneous group of genetic disorders with more than 90 causative genes. Clinically, HSP is classified into pure and complicated forms. Pure forms are characterized primarily by lower-limb spasticity and weakness, whereas complicated forms include additional neurological or non-neurological symptoms alongside spasticity and weakness. We aimed to characterize the clinical and genetic landscapes of HSP in an Iranian cohort. Whole-exome sequencing (WES) was performed on 103 unrelated clinically suspected HSP probands. Multiple ligation-dependent probe amplification (MLPA) was performed to validate identified copy number variants (CNVs) in two probands. Results 71 pathogenic/likely pathogenic and VUS variants were identified in 81 probands; total genetically solved probands: 78.6%. Among these solved cases, 64 probands harbored variants in known HSP genes, 14 had variants in other neuromuscular/neurodegenerative-related genes, and the remaining 3 probands carried variants in four novel candidate genes including NMNAT1, SEMA3A, KCNJ14, and EMP3. Among all 71 identified genomic variants, two were CNVs and one was a trinucleotide repeat expansion. Taken together, these variants were located in 37 genes; 21 of these genes have been previously implicated in HSP, and four common HSP subtypes (SPG11, SPG4, SPG7, and SPG15) accounted for ~40% of our cohort. Conclusions This study demonstrates significant clinical and genetic heterogeneity of HSP within our cohort. In addition to variants in 21 known HSP-related genes, we identified variants in 14 genes related to other neurological disorders -highlighting shared biological pathways- as well as variants in four novel candidate genes. Notably, a genetic diagnosis could not be established in 22 probands, underscoring that additional, as yet unidentified genes likely contribute to HSP pathogenesis.
2026-01-26 | Pharmacological Restoration of Mitochondrial Permeability Transition Pore Flickering by High-Content Drug Repurposing
Abstract The mitochondrial permeability transition pore (mPTP) is a voltage- and calcium-regulated channel located in the inner mitochondrial membrane whose activity critically influences cellular fate. While prolonged pore opening leads to mitochondrial depolarization, matrix swelling, and cell death, brief and reversible opening events, referred to as flickering, enable controlled release of calcium and reactive oxygen species and serve essential physiological functions. Emerging evidence indicates that restoring physiological mPTP flickering, rather than suppressing pore activity, may be beneficial in disorders characterized by impaired pore dynamics, including hereditary spastic paraplegia type 7 (SPG7). However, no approved therapies are currently available to promote controlled mPTP pore opening. To identify pharmacological modulators of flickering, we performed a high-content screening of 2,000 FDA and EMA-approved compounds using a validated fluorescence-based assay coupled with automated image analysis. Thirteen compounds increased both the frequency and the area of flickering events while preserving cellular and mitochondrial integrity. Validation in fibroblasts derived from two SPG7 patients and healthy controls confirmed reproducible activity across distinct genetic backgrounds. Among the prioritized candidates, berberine emerged as the most robust modulator, consistently enhancing mPTP flickering independently of SPG7 mutation status. Notably, berberine selectively increased the proportion of small-size flickering events, indicative of physiological pore activity. These findings identify berberine as a promising modulator of mPTP dynamics and support pharmacological restoration of physiological flickering as a potential therapeutic strategy for SPG7 and other disorders associated with impaired mitochondrial permeability transition pore regulation.
2025-08-09 | Charting the genetic landscape of autosomal recessive hereditary spastic paraplegia: A deep dive into 10 exceptionally rare cases.
Hereditary spastic paraplegias (HSPs) are a genetically and clinically heterogeneous group of neurodegenerative disorders primarily characterized by progressive lower limb spasticity and weakness. Autosomal recessive HSPs (AR HSPs) are rare and account for approximately 30% of cases, with a higher prevalence in populations with increased consanguinity rates. In this study, we investigated 10 patients diagnosed with AR HSPs and identified pathogenic variants in SPART, FA2H, AP4B1, SPG7, SPG11, CYP2U1, and CYP7B1, with three cases harboring novel variants. Clinical presentations ranged from pure spastic paraplegia to complex phenotypes involving intellectual disability, ataxia, dysarthria, joint abnormalities, and systemic features. Exome sequencing and detailed bioinformatics analyses were employed to identify causative variants, which were classified based on ACMG criteria. The study expands the known genetic spectrum of AR HSPs by reporting previously undescribed variants and providing insight into their potential pathogenic mechanisms. The presence of distinct clinical features in patients with the same genetic variant emphasizes the complexity of genotype-phenotype correlations in HSP. Our findings highlight the importance of genetic testing in early diagnosis and clinical management of HSP, enabling more precise prognostic evaluations and potential therapeutic interventions. Given the high consanguinity rates in certain populations, targeted genetic screening may facilitate early detection and personalized treatment strategies. Further functional studies are needed to elucidate the molecular impact of these novel variants and their role in disease progression, potentially paving the way for future gene-based therapies.
2026-06-30 | Berberine improves motor deficits in the spastic paraplegia SPG7 mutant mice
Abstract Hereditary spastic paraplegia type 7 (SPG7) is a neurodegenerative disorder characterized by progressive motor impairment and cerebellar dysfunction. Mutations in the SPG7 gene, encoding the mitochondrial metalloprotease paraplegin, disrupt mitochondrial homeostasis and lead to neuronal vulnerability and deficits in motor coordination. Recent studies have identified defective flickering of the mitochondrial permeability transition pore (mPTP) in SPG7 models, suggesting that altered pore dynamics may represent a functional biomarker of mitochondrial dysfunction. Here, we investigated whether pharmacological modulation of mPTP activity could improve mitochondrial function and motor performance in SPG7 models. Mitochondrial flickering was assessed in vitro , while motor behavior was evaluated in vivo following chronic treatment with berberine, a natural isoquinoline alkaloid known to modulate mitochondrial bioenergetics. Spg7 −/− mice and age-matched Spg7 +/ littermate controls received daily oral berberine administration for several weeks, and motor coordination was assessed using the accelerating rotarod test. Untreated Spg7 −/− mice exhibited reduced rotarod performance compared with controls, indicating impaired motor coordination. Berberine treatment significantly improved motor performance in pre-symptomatic mutant mice. These findings indicate that pharmacological modulation of mitochondrial permeability transition pore dynamics can ameliorate motor dysfunction associated with SPG7 deficiency and highlight mPTP flickering as a functional readout of mitochondrial health.
2026-06-29 | Rescue of mitochondrial and neurite pathology in SPG7 hereditary spastic paraplegia patient-derived cortical neurons.
Biallelic pathogenic variants in SPG7 are a frequent cause of hereditary spastic paraplegia leading to progressive disability due to a length-dependent degeneration of cerebellar and cortical projection neurons. While underlying mechanisms have been linked to impaired mitochondrial function, no disease-modifying therapy is available. We generated induced pluripotent stem cell-derived cortical neurons from SPG7 patients with non-sense or truncating variants and from matched controls. We performed detailed phenotyping of neuronal differentiation, as well as mitochondrial and neuritic morphology and function. We explored the effects of Bz-423, a modulator of the mitochondrial permeability transition pore, as a potential rescue of SPG7-specific cellular phenotypes. We successfully differentiated SPG7 patient-derived neurons, without quantitative differences in differentiation compared with controls. However, we delineate neurite-specific aberrations of mitochondrial morphology and ultrastructure. Moreover, anterograde axonal mitochondrial transport was impaired in SPG7. Exposure to Bz-423 rescued ultrastructural and functional phenotypes. In summary, our data show impaired neuritic mitochondria in a patient-specific human model, and we here demonstrate for the first time beneficial effects of Bz-423 on neuritic ultrastructure and function in a human neuronal SPG7 system. Moreover, we identify the mitochondrial permeability transition pore as a molecular target to rescue phenotypes also in carriers of non-sense or truncating SPG7 variants.
2026-05-12 | Expanding the genetic and clinical landscapes of hereditary spastic paraplegia (HSP): a cohort study of 103 families
Abstract Background Hereditary spastic paraplegia (HSP) refers to a heterogeneous group of genetic disorders with more than 90 causative genes. Clinically, HSP is classified into pure and complicated forms. Pure forms are characterized primarily by lower-limb spasticity and weakness, whereas complicated forms include additional neurological or non-neurological symptoms alongside spasticity and weakness. We aimed to characterize the clinical and genetic landscapes of HSP in an Iranian cohort. Whole-exome sequencing (WES) was performed on 103 unrelated clinically suspected HSP probands. Multiple ligation-dependent probe amplification (MLPA) was performed to validate identified copy number variants (CNVs) in two probands. Results 71 pathogenic/likely pathogenic and VUS variants were identified in 81 probands; total genetically solved probands: 78.6%. Among these solved cases, 64 probands harbored variants in known HSP genes, 14 had variants in other neuromuscular/neurodegenerative-related genes, and the remaining 3 probands carried variants in four novel candidate genes including NMNAT1, SEMA3A, KCNJ14, and EMP3. Among all 71 identified genomic variants, two were CNVs and one was a trinucleotide repeat expansion. Taken together, these variants were located in 37 genes; 21 of these genes have been previously implicated in HSP, and four common HSP subtypes (SPG11, SPG4, SPG7, and SPG15) accounted for ~40% of our cohort. Conclusions This study demonstrates significant clinical and genetic heterogeneity of HSP within our cohort. In addition to variants in 21 known HSP-related genes, we identified variants in 14 genes related to other neurological disorders -highlighting shared biological pathways- as well as variants in four novel candidate genes. Notably, a genetic diagnosis could not be established in 22 probands, underscoring that additional, as yet unidentified genes likely contribute to HSP pathogenesis.
2026-01-26 | Pharmacological Restoration of Mitochondrial Permeability Transition Pore Flickering by High-Content Drug Repurposing
Abstract The mitochondrial permeability transition pore (mPTP) is a voltage- and calcium-regulated channel located in the inner mitochondrial membrane whose activity critically influences cellular fate. While prolonged pore opening leads to mitochondrial depolarization, matrix swelling, and cell death, brief and reversible opening events, referred to as flickering, enable controlled release of calcium and reactive oxygen species and serve essential physiological functions. Emerging evidence indicates that restoring physiological mPTP flickering, rather than suppressing pore activity, may be beneficial in disorders characterized by impaired pore dynamics, including hereditary spastic paraplegia type 7 (SPG7). However, no approved therapies are currently available to promote controlled mPTP pore opening. To identify pharmacological modulators of flickering, we performed a high-content screening of 2,000 FDA and EMA-approved compounds using a validated fluorescence-based assay coupled with automated image analysis. Thirteen compounds increased both the frequency and the area of flickering events while preserving cellular and mitochondrial integrity. Validation in fibroblasts derived from two SPG7 patients and healthy controls confirmed reproducible activity across distinct genetic backgrounds. Among the prioritized candidates, berberine emerged as the most robust modulator, consistently enhancing mPTP flickering independently of SPG7 mutation status. Notably, berberine selectively increased the proportion of small-size flickering events, indicative of physiological pore activity. These findings identify berberine as a promising modulator of mPTP dynamics and support pharmacological restoration of physiological flickering as a potential therapeutic strategy for SPG7 and other disorders associated with impaired mitochondrial permeability transition pore regulation.
2025-08-09 | Charting the genetic landscape of autosomal recessive hereditary spastic paraplegia: A deep dive into 10 exceptionally rare cases.
Hereditary spastic paraplegias (HSPs) are a genetically and clinically heterogeneous group of neurodegenerative disorders primarily characterized by progressive lower limb spasticity and weakness. Autosomal recessive HSPs (AR HSPs) are rare and account for approximately 30% of cases, with a higher prevalence in populations with increased consanguinity rates. In this study, we investigated 10 patients diagnosed with AR HSPs and identified pathogenic variants in SPART, FA2H, AP4B1, SPG7, SPG11, CYP2U1, and CYP7B1, with three cases harboring novel variants. Clinical presentations ranged from pure spastic paraplegia to complex phenotypes involving intellectual disability, ataxia, dysarthria, joint abnormalities, and systemic features. Exome sequencing and detailed bioinformatics analyses were employed to identify causative variants, which were classified based on ACMG criteria. The study expands the known genetic spectrum of AR HSPs by reporting previously undescribed variants and providing insight into their potential pathogenic mechanisms. The presence of distinct clinical features in patients with the same genetic variant emphasizes the complexity of genotype-phenotype correlations in HSP. Our findings highlight the importance of genetic testing in early diagnosis and clinical management of HSP, enabling more precise prognostic evaluations and potential therapeutic interventions. Given the high consanguinity rates in certain populations, targeted genetic screening may facilitate early detection and personalized treatment strategies. Further functional studies are needed to elucidate the molecular impact of these novel variants and their role in disease progression, potentially paving the way for future gene-based therapies.
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0 orphan drug designations.
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