About

Defne Amado, MD, PhD, is an Assistant Professor of Neurology at the Hospital of the University of Pennsylvania within the Department of Neurology. She specializes in clinical care for patients with amyotrophic lateral sclerosis (ALS), treating patients at the Penn Comprehensive ALS Center, and also manages a general neuromuscular clinic focusing on inherited and acquired neuropathies. She spends approximately 20% of her time on clinical practice, attending on the inpatient service. Her research interests are centered on using gene therapy-based approaches to understand and develop treatments for neurodegenerative diseases, particularly ALS. Her lab specializes in pathobiologic discovery and gene therapy therapeutic development, working across models from induced pluripotent stem cells (iPSCs) to mice, primarily utilizing AAV-based delivery systems. Her work aims to understand the pathogenic basis of neurodegeneration in ALS, frontotemporal dementia, and spinocerebellar ataxia, and to develop therapeutic interventions targeting these pathways. Dr. Amado has a strong background in neurobiology and gene therapy, having completed her PhD with Dr. Jean Bennett and postdoctoral training with Dr. Alice Chen-Plotkin and Dr. Beverly Davidson. In addition to her research, she is actively involved in translational medicine, integrating her clinical expertise with her laboratory work. Her lab fosters an inclusive, diverse, and engaging environment for trainees. Her notable contributions include advancing gene therapy techniques for neurodegenerative diseases and presenting her research at major scientific meetings, with her work recognized through awards and plenary presentations.

Research topics

• Medicine
• Internal medicine
• Psychiatry
• Bioinformatics
• Intensive care medicine
• Pathology
• Physical medicine and rehabilitation
• Gerontology
• Demography
• Neuroscience
• Biology
• Genetics
• Environmental health
• Psychology
• Family medicine

Selected publications

• Dissecting the relationship between haplotypes around ATXN2 CAG repeats and the number of CAA interruptions by long-read sequencing

  medRxiv · 2026-03-12

  articleOpen access

  Abstract CAG repeat expansions in ATXN2 are implicated as risk factors for neurological diseases, including amyotrophic lateral sclerosis (ALS) when 27-33 CAG (intermediate) repeats are present. However, how haplotypes around the repeats and CAA interruptions within the repeats are associated with diseases remains poorly understood. Here, we used long-read sequencing on the Oxford Nanopore technologies (ONT) platform to simultaneously infer haplotypes around ATXN2 , the number of CAG repeats, and the number of CAA interruptions. We found that haplotypes around ATXN2 and the number of interruptions show ethnicity-specific and ALS-specific distribution. Three CAA interruptions are present at low prevalence (∼1%) in control populations in multiple ancestry groups, but high prevalence (∼55%) in ALS individuals with intermediate repeats. Furthermore, we examined 159 individuals with ALS (∼90% European ancestry) with intermediate ATXN2 repeats and found a unique haplotype in ALS individuals with three CAA interruptions, which can be tagged by an SNV, rs148019457. We further sequenced 41 individuals (EUR = 39) with neurological diseases with intermediate repeats by ONT, and validated that the rs148019457-G allele is only present in haplotypes with three CAA interruptions. Our study shows that 3 CAA interruptions are rare in healthy controls but are common in individuals with intermediate ATXN2 CAG repeats and neurological disorders, and that rs148019457 tags a specific haplotype with 3 CAA interruptions in individuals of European ancestry. These results have implications for the development of precision genomic medicine for neurological disorders, and the tag SNV may help identify those with interruptions from existing microarray genotyping data.

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• Genotype and phenotype spectrum of Charcot-Marie-Tooth disease due to mutations in SORD

  Brain · 2025-01-27 · 7 citations

  articleOpen access

  Biallelic loss-of-function mutations in the sorbitol dehydrogenase (SORD) gene cause the most common recessive type of Charcot-Marie-Tooth disease (CMT), CMT-SORD. However, the full genotype-phenotype spectrum and progression of the disease remain to be defined. Notably, a multicentre phase 2/3 study to test the efficacy of govorestat (NCT05397665), a new aldose reductase inhibitor, is currently ongoing. Diagnosing CMT-SORD will become imperative when disease-modifying therapies become available. In this cross-sectional multicentre study, we identified 144 patients from 126 families, including 99 males (69%) and 45 females (31%). Patients represented multiple ancestries, including European, Hispanic, Chinese, Near Eastern and Northern African. We confirmed c.757delG (p.Ala253GlnfsTer27) as the most common pathogenic allele, followed by c.458C>A (p.Ala153Asp), while other variants were identified, mostly in single cases. The average sorbitol level in CMT-SORD patients was significantly higher compared to controls and heterozygous carriers, independently from serum storage duration, sex or variant type. Two-thirds of cases were diagnosed with CMT2 while one-third had distal hereditary motor neuropathy. Disease onset was usually in the second decade of life. Although foot dorsiflexion was the most affected muscle group, dorsal and plantar flexion had a similar degree of weakness in most cases (difference of Medical Research Council score ≤ 1). One-fourth of patients used ankle foot orthoses, usually in their 30s, but most patients maintained independent ambulation later in life. Nerve conduction studies were suggestive of a motor predominant axonal neuropathy, with reduced conduction velocities in the intermediate range in a quarter of the cases. Sensory conductions in the upper limbs appeared more frequently affected than in the lower limbs. Foot dorsiflexion and plantar flexion decreased significantly with age. Male sex was significantly associated with the severity of distal lower limb weakness (plantar flexion) and a larger change over time (dorsiflexion). In conclusion, CMT-SORD is a frequent recessive form of axonal, motor predominant CMT, with prominent foot dorsiflexion and plantar flexion involvement. Fasting serum sorbitol is a reliable biomarker of the condition that can be utilized for pathogenicity assessment of identified rare SORD variants.

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• AAV-based delivery of RNAi targeting ataxin-2 improves survival and pathology in TDP-43 mice

  Nature Communications · 2025-06-25 · 7 citations

  articleOpen access1st authorCorresponding

  Amyotrophic lateral sclerosis (ALS) involves motor neuron death due to mislocalized TDP-43. Pathologic TDP-43 associates with stress granules (SGs), and lowering the SG-associated protein ataxin-2 (ATXN2) using Atxn2-targeting antisense oligonucleotides prolongs survival in TAR4/4 sporadic ALS mice but failed in clinical trials likely due to poor target engagement. Here we show that an AAV with potent motor neuron transduction delivering Atxn2-targeting miRNAs reduces Atxn2 throughout the central nervous system at doses 40x lower than published work. In TAR4/4 mice, miAtxn2 increased survival (50%) and strength, and reduced motor neuron death, inflammation, and phosphorylated TDP-43. TAR4/4 transcriptomic dysregulation recapitulated ALS gene signatures that were rescued by miAtxn2, identifying potential therapeutic mechanisms and biomarkers. In slow progressing hemizygous mice, miAtxn2 slowed disease progression, and in ALS patient-derived lower motor neurons, our AAV vector transduced >95% of cells and potently reduced ATXN2 at MOI 4 logs lower than previously reported. These data support AAV-RNAi targeting ATXN2 as a translatable therapy for sporadic ALS. Amado et al. develop a gene therapy for sporadic ALS using motor neuron-targeting AAVs to deliver RNAi targeting ataxin-2. In a mouse model, survival, strength, and disease-related pathology are improved; and human motor neurons are strongly transduced.

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• Cumulative incidence of motor and cognitive features in the amyotrophic lateral sclerosis—frontotemporal degeneration spectrum

  Brain Communications · 2025-01-01

  articleOpen access

  Abstract In frontotemporal degeneration and amyotrophic lateral sclerosis, subsequent motor or cognitive-behavioural features, respectively, are associated with shorter survival. However, factors influencing subsequent feature development remain largely unexplored. In this study, we examined whether the presence of a C9orf72 expansion or the initial clinical syndrome was associated with increased risk of subsequent feature development in individuals with amyotrophic lateral sclerosis and frontotemporal degeneration. We performed a retrospective evaluation of the entire disease course of individuals with an initial clinical syndrome of amyotrophic lateral sclerosis or frontotemporal degeneration who had neuropathological confirmation of TDP-43 proteinopathy at autopsy or a C9orf72 hexanucleotide repeat expansion. We examined the odds and hazard of subsequent feature development and assessed whether each was modified by the presence of a C9orf72 expansion or initial clinical syndrome. At autopsy, we evaluated the association between TDP-43 pathology burden in characteristic brain regions and features across this disease spectrum. For individuals with amyotrophic lateral sclerosis (n = 168) and frontotemporal degeneration (n = 73), binary logistic regression revealed increased odds (odds ratio = 3.49 [95% confidence interval 1.64–7.80], P = 0.002) and Cox proportional hazard analyses revealed an increased hazard (hazard ratio = 3.78 [95% confidence interval 1.86–7.65], P < 0.001) for developing subsequent features in those with a C9orf72 expansion compared to those without. Beyond C9orf72 expansion status, binary logistic regression revealed decreased odds (odds ratio = 0.25 [95% confidence interval 0.12–0.53], P < 0.001) and Cox proportional hazard analyses revealed a decreased hazard (hazard ratio = 0.48 [95% confidence interval 0.25–0.95], P = 0.03) for developing subsequent features in those with an initial amyotrophic lateral sclerosis clinical syndrome compared to those with an initial frontotemporal degeneration clinical syndrome. We observed a 94-month difference in the time after symptom onset of the initial clinical syndrome that a given person without a C9orf72 expansion reached the highest probability of developing subsequent features (0.12 [95% CI 0.03–0.19], 113.00 months) and a person with a C9orf72 expansion surpassed that probability (0.13 [95% CI 0.06–0.19], 19.00 months). The distribution of TDP-43 pathology across characteristic brain regions reflected both the initial clinical syndrome and subsequent features, with relatively preserved spinal cord only in frontotemporal degeneration cases without subsequent motor features (P < 0.0001) and relatively preserved neocortical regions only in amyotrophic lateral sclerosis cases without subsequent cognitive-behavioural features (P < 0.0001). These data highlight the need for clinician vigilance to detect the onset of subsequent motor and cognitive-behavioural features in patients carrying a C9orf72 expansion, regardless of initial clinical syndrome. C9orf72 clinical care can be enhanced through coordination between cognitive and neuromuscular clinics.

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• Polygenic associations with clinical and neuropathological trait heterogeneity across TDP-43 proteinopathies

  PLoS ONE · 2025-12-30

  articleOpen access

  TDP-43 proteinopathies, including amyotrophic lateral sclerosis (ALS), frontotemporal lobar degeneration with TDP-43 (FTLD-TDP), and limbic-predominant age-related TDP-43 encephalopathy, encompass a spectrum of clinical and neuropathological traits. Despite mounting evidence for shared genetic risk across TDP-43 proteinopathies, the modifiers of individual-level traits are unknown. We aimed to identify polygenic contributions to trait heterogeneity across TDP-43 proteinopathies. We used weighted correlation analysis of GWAS summary statistics for ALS, FTLD-TDP, and hippocampal sclerosis of aging (HS-Aging) to identify data-driven clusters of highly correlated single nucleotide polymorphisms (SNPs). We performed gene ontology enrichment analysis for each identified cluster. We derived cluster-specific polygenic scores and evaluated their association with clinical and neuropathological traits in an independently evaluated sample of individuals who met neuropathological and/or genetic criteria for FTLD-TDP or ALS (n = 260). We identified 5 distinct data-driven clusters, including 3 GWAS phenotype-specific clusters (FTLD-TDP, ALS, HS-Aging) and 2 clusters representing the overlap between a pair of GWAS phenotypes (ALS-FTLD and FTLD-HS). Pathway analysis revealed biologically meaningful associations including distinct GWAS phenotype-specific processes within clusters. Cluster-specific ALS and FTLD-TDP polygenic risk each associated with individual-level clinical traits, even within the context of autosomal dominant mutation carriers, where higher ALS polygenic risk associated with neuromuscular impairment and higher FTLD-TDP polygenic risk associated with cognitive-behavioral impairment. Moreover, higher FTLD-TDP polygenic risk associated with higher TDP-43 burden within characteristic FTLD-TDP brain regions. We suggest that there are polygenic modifiers of clinical and neuropathological traits across TDP-43 proteinopathies that may contribute to individual-level differences, including likelihood for developing FTLD or ALS.

  PublisherDOI

• Thalamic volume as a susceptibility/risk biomarker for <i>C9orf72</i> phenoconversion

  medRxiv · 2025-09-21

  preprintOpen access

  Abstract Background C9orf72 repeat expansions are the most frequent genetic risk factor of amyotrophic lateral sclerosis (ALS) and frontotemporal degeneration (FTD). With growing interest in the prospect of preventing clinically manifest disease, there is a pressing need to identify susceptibility/risk biomarkers that might predict the short-term risk of phenoconversion. This study sought to identify such neuroimaging biomarkers that predict the risk of ALS or FTD among unaffected C9orf72 carriers. Methods Our cohort comprised 4 groups of participants genotyped for C9orf72 repeat expansions, including 73 pre-symptomatic carriers, 8 phenoconverters, 49 affected carriers, and 99 non-carrier controls. Pre-symptomatic carriers remained unaffected throughout the follow-up period, while phenoconverters were those who transitioned from pre-symtpomatic to the clinically manifest phase during follow-up. Affected carriers were already diagnosed with ALS and/or FTD at baseline. All participants underwent an initial MRI scan, with a subset receiving follow-up MRI scans. Regional gray matter volumes were analyzed to assess initial differences across groups, to predict phenoconversion from a pre-symptomatic to clinically manifest state, and to explore progression over time. Results Group comparisons revealed an increasing extent and magnitude of reduced gray matter volume across the clinical continuum, from pre-symptomatic to clinically manifest stages, with phenoconverters who were imaged when pre-symptomatic and later developed clinically manifest disease intermediate between the two. The thalamus demonstrates the largest effect and the least variability across centers and MRI protocols. Thalamic volume is, on average, lower among pre-symptomatic carriers than non-carrier controls, though with wide overlapping distributions. Phenoconverters exhibited thalamic volumes in the range of affected carriers, both before and after phenoconversion. Mean thalamic volume discriminated between phenoconverters and carriers who remained pre-symptomatic during follow-up with an area under the curve of 0.854 (p&lt;0.001), and time-to-phenoconversion analysis demonstrated that individuals with a lower baseline thalamic volume had an increased hazard for phenoconversion (HR=17.6; CI=2.2-143.3; p&lt;0.001). Other regions, including the amygdala, somatomotor cortex, postcentral gyrus, and parietal cortex, demonstrated less consistent signals across centers and MRI protocols, but generally followed trends similar to the thalamus. Longitudinal observations further indicated that these regions, particularly the thalamus, demonstrated consistent downward trajectories over time, with more rapid atrophy observed in phenoconverters and affected carriers. Conclusions Lower thalamic volume is a promising susceptibility/risk biomarker predicting phenoconversion to clinically manifest ALS or FTD among clinically unaffected C9orf72 repeat expansion carriers, with potential utility to aid the design and implementation of early intervention and preventative clinical trials.

  PublisherOA PDFDOI

• Author Correction: AAV-based delivery of RNAi targeting ataxin-2 improves survival and pathology in TDP-43 mice

  Nature Communications · 2025-10-23 · 1 citations

  articleOpen access1st authorCorresponding

  In the version of the article initially published, a reference citation was missing in the first sentence of the Results "Translatability to human targets" section, which now reads "To determine the ability of miAtxn2 to target human ATXN2, we used the 127Q transgenic mouse model of spinocerebellar ataxia type 2, in which mice overexpress mutant human ATXN2 in cerebellar Purkinje cells [Hansen, S.

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• Scouring the human Hsp70 network uncovers diverse chaperone safeguards buffering TDP-43 toxicity

  bioRxiv (Cold Spring Harbor Laboratory) · 2025-05-10 · 1 citations

  preprintOpen access

  Cytoplasmic aggregation and concomitant dysfunction of the prion-like, RNA-binding protein TDP-43 underpin several fatal neurodegenerative diseases, including amyotrophic lateral sclerosis. To elucidate endogenous defenses, we systematically scoured the entire human Hsp70 network for buffers of TDP-43 toxicity. We identify 30 J-domain proteins (2 DNAJAs, 10 DNAJBs, 18 DNAJCs), 6 Hsp70s, and 5 nucleotide-exchange factors that mitigate TDP-43 toxicity. Specific chaperones reduce TDP-43 aggregate burden and detoxify diverse synthetic or disease-linked TDP-43 variants. Sequence-activity mapping unveiled unexpected, modular mechanisms of chaperone-mediated protection. Typically, DNAJBs collaborate with Hsp70 to suppress TDP-43 toxicity, whereas DNAJCs act independently. In human cells, specific chaperones increase TDP-43 solubility and enhance viability under proteotoxic stress. Strikingly, spliceosome-associated DNAJC8 and DNAJC17 retain TDP-43 in the nucleus and promote liquid-phase behavior. Thus, we disambiguate a diverse chaperone arsenal embedded in the human proteostasis network that counters TDP-43 toxicity and illuminate mechanistic gateways for therapeutic intervention in TDP-43 proteinopathies.

  PublisherOA PDFDOI

• C9orf72 repeat expansions increase risk for secondary symptom development in amyotrophic lateral sclerosis and behavioral‐variant frontotemporal degeneration

  Alzheimer s & Dementia · 2024-12-01

  articleOpen access

  BACKGROUND: In amyotrophic lateral sclerosis and behavioral-variant frontotemporal degeneration, the presence of secondary cognitive-behavioral or motor symptoms, respectively, is associated with shorter survival. However, factors influencing the risk of secondary symptom development remain largely unexplored and time-to-event characterization for developing secondary symptoms is important for prognostic clinical decision-making. METHOD: We performed a retrospective evaluation of the entire disease course of individuals in the Penn Integrated Neurodegenerative Disease Database with a primary clinical phenotype of amyotrophic lateral sclerosis (n = 173) or behavioral-variant frontotemporal degeneration (n = 69). All individuals were evaluated for C9orf72 expansions (>30 repeats). Only individuals who had neuropathological confirmation of a TDP-43 proteinopathy at autopsy or had a C9orf72 repeat expansion were included for analysis. We examined the odds and hazard of secondary symptom development and assessed whether they were modified by the presence of a C9orf72 repeat expansion or primary clinical phenotype. RESULT: Binary logistic regression and Cox proportional hazard analyses revealed increased odds (odds ratio = 4.26 [1.98-9.18]; p<0.001) and an increased hazard (hazard ratio = 4.79 [2.33- 9.82], p<0.001) for developing secondary symptoms in C9orf72 expansion carriers compared to noncarriers. Primary phenotype, age at symptom onset, and sex were not associated with risk for secondary symptom development. CONCLUSION: These findings highlight the need for clinician vigilance to detect the onset of secondary cognitive-behavioral and motor symptoms in patients carrying a C9orf72 repeat expansion, regardless of primary phenotype, and may warrant dual referrals between cognitive and neuromuscular clinics in these cases.

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• Cognitive reserve in ALS: the role of occupational skills and requirements

  Amyotrophic Lateral Sclerosis and Frontotemporal Degeneration · 2024 · 6 citations

  • Physical medicine and rehabilitation
  • Psychology
  • Neuroscience

  OBJECTIVE: Amyotrophic Lateral Sclerosis (ALS) is a heterogeneous neurodegenerative condition featuring variable degrees of motor and cognitive impairment. We assessed the impact of specific, empirically derived occupational skills and requirements on cognitive and motor functioning in ALS. METHODS: Individuals with ALS (n = 150) were recruited from the University of Pennsylvania's Comprehensive ALS Clinic. The Edinburgh Cognitive and Behavioral ALS Screen (ECAS) measured cognition, and the Penn Upper Motor Neuron (PUMNS) and ALS Functional Rating Scales (ALSFRS-R) measured motor symptoms. We derived 17 factors representing distinct occupational skills and requirements from the Occupational Information Network (O*NET), which were related to cognitive and motor scores using multiple linear regression. RESULTS: < .05) were associated with greater motor dysfunction on the PUMNS. CONCLUSIONS: Occupational histories involving more cognitively complex skills and activities were related to preserved cognitive functioning in ALS consistent with the cognitive reserve hypothesis, while jobs with greater exposure to environmental hazards and technical demands were linked to poorer cognitive functioning. Jobs involving more repetitive movements were associated with worse motor functioning, possibly due to overuse. Occupational history provides insight into protective and risk factors for variable degrees of cognitive and motor dysfunction in ALS.

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Frequent coauthors

• Lauren Elman

  University of Pennsylvania

  23 shared

• Colin Quinn

  University of Pennsylvania

  21 shared

• Beverly L. Davidson

  19 shared

• Michael Baer

  17 shared

• Corey T. McMillan

  University of Pennsylvania

  14 shared

• Jean Bennett

  University of Pennsylvania

  14 shared

• David J. Irwin

  University of Pennsylvania

  13 shared

• Murray Grossman

  12 shared

Labs

• Defne Amado LabPI

Education

• Postdoctoral Research Fellow

  University of Pennsylvania

  2021

• Neuromuscular Research Fellowship, Neurology

  University of Pennsylvania

  2016

• Neurology Residency, Neurology

  University of Pennsylvania

  2015

• Internship, Medicine

  University of Pennsylvania

  2012

• MD, PhD

  University of Pennsylvania

  2011

• BA, Neuroscience

  Columbia University

  2003

Awards & honors

• Emerging Scholars Award (2023)
• Travel Award (2023)
• Top Abstract of >1600 abstracts (2023)