Explore the vast range of titles available.

Few disciplines in contemporary clinical research have experienced the high expectations directed at the gene therapy field. However, gene therapy has been challenging to translate to the clinic, often because the therapeutic gene is expressed at insufficient levels in the patient or because the gene delivery vector integrates near protooncogenes, which can cause leukemia (see the Perspective by Verma ). Biffi et al. ( 1233158 , published online 11 July) and Aiuti et al. ( 1233151 ; published online 11 July) report progress on both fronts in gene therapy trials of three patients with metachromatic leukodystrophy (MLD), a neurodegenerative disorder, and three patients with Wiskott-Aldrich syndrome (WAS), an immunodeficiency disorder. Optimized lentiviral vectors were used to introduce functional MLD or WAS genes into the patients' hematopoietic stem cells (HSCs) ex vivo, and the transduced cells were then infused back into the patients, who were then monitored for up to 2 years. In both trials, the patients showed stable engraftment of the transduced HSC and high expression levels of functional MLD or WAS genes. Encouragingly, there was no evidence of lentiviral vector integration near proto-oncogenes, and the gene therapy treatment halted disease progression in most patients. A longer follow-up period will be needed to further validate efficacy and safety. Lentivirus-mediated gene therapy produces encouraging results in three children with a rare lysosomal storage disease. [Also see Perspective by Verma ] Metachromatic leukodystrophy (MLD) is an inherited lysosomal storage disease caused by arylsulfatase A (ARSA) deficiency. Patients with MLD exhibit progressive motor and cognitive impairment and die within a few years of symptom onset. We used a lentiviral vector to transfer a functional ARSA gene into hematopoietic stem cells (HSCs) from three presymptomatic patients who showed genetic, biochemical, and neurophysiological evidence of late infantile MLD. After reinfusion of the gene-corrected HSCs, the patients showed extensive and stable ARSA gene replacement, which led to high enzyme expression throughout hematopoietic lineages and in cerebrospinal fluid. Analyses of vector integrations revealed no evidence of aberrant clonal behavior. The disease did not manifest or progress in the three patients 7 to 21 months beyond the predicted age of symptom onset. These findings indicate that extensive genetic engineering of human hematopoiesis can be achieved with lentiviral vectors and that this approach may offer therapeutic benefit for MLD patients.

Metachromatic leukodystrophy (MLD) is an autosomal recessive neurodegenerative disorder caused by mutations in the arylsulfatase A (ARSA) gene, resulting in lower sulfatase activity and the toxic accumulation of sulfatides in the central and peripheral nervous system. Children account for 70% of cases and become progressively disabled, with death occurring within 10 years of disease onset. Gene therapy approaches to restore ARSA expression via adeno-associated virus (AAV) vectors have been promising but hampered by limited brain biodistribution. We report the development of an engineered capsid, AAV.GMU01, demonstrating superior biodistribution and transgene expression in the central nervous system of nonhuman primates (NHPs). Next, we show that AAV.GMU01-ARSA-treated MLD mice exhibit persistent, normal levels of sulfatase activity and a concomitant reduction in toxic sulfatides. Treated mice also show a reduction in MLD-associated pathology and auditory dysfunction. Lastly, we demonstrate that treatment with AAV.GMU01-ARSA in NHPs is well tolerated and results in potentially therapeutic ARSA expression in the brain. In summary, we propose AAV.GMU01-ARSA-mediated gene replacement as a clinically viable approach to achieve broad and therapeutic levels of ARSA.

Background Metachromatic Leukodystrophy (MLD) is a rare, fatal demyelinating disorder with limited treatment options. Published outcomes after hematopoietic stem cell transplantation (HSCT) are scant and mixed. We report survival and function following HSCT for a large, single-center MLD cohort. Methods Transplant-related data, survival and serial measures (brain MRI, nerve conduction velocity (NCV), neurologic and neuropsychology evaluations) were reviewed. When possible, parental interviews informed current neurologic status, quality-of-life, and adaptive functioning. Gross motor and expressive functions for late-infantile (LI-MLD) and juvenile (J-MLD) patients were described using previously reported, MLD-specific scales. Results Forty patients with confirmed MLD have undergone HSCT at our center. Twenty-one (53 %) survive at a median 12 years post-HSCT. Most deaths (n = 17) were treatment-related; two died from disease progression. Survival did not depend upon MLD subtype or symptom status at transplant. LI-MLD patients survive beyond reported life expectancy in untreated disease. Abnormal brain MRI and peripheral nerve conduction velocities (NCV) were common before HSCT. Following transplant, fewer patients experienced MRI progression compared to NCV deterioration. Sixteen LI-MLD and J-MLD survivors were evaluable for long-term gross motor and/or expressive language functioning using existing MLD clinical scoring systems. While most J-MLD patients regressed, the aggregate cohort demonstrated superior retention of function compared to published natural history. Seventeen LI-MLD, J-MLD and adult subtype (A-MLD) survivors were evaluable for long-term adaptive functioning, activities of daily living, and/or cognition. Relative cognitive sparing was observed despite overall global decline. Five sibling pairs (one LI-MLD and four J-MLD), in which at least one underwent transplant in our cohort, were evaluable. Within each familial dyad, survival or function was superior for the treated sibling, or if both siblings were transplanted, for the pre-symptomatic sibling. Conclusions HSCT is a viable treatment option for MLD, but has significant limitations. Later-onset phenotypes may benefit most from early, pre-symptomatic transplant. Until superior, novel treatment strategies are demonstrated, MLD patients should be carefully considered for HSCT.

Objectives The leukodystrophy “vanishing white matter” (VWM) and “metachromatic leukodystrophy” (MLD) affect the brain's white matter, but have very different underlying pathology. We aim to determine whether quantitative MRI reflects known neuropathological differences and correlates with clinical scores in these leukodystrophies. Methods VWM and MLD patients and controls were prospectively included between 2020 and 2023. Clinical scores were recorded. MRI at 3 T included multi-compartment relaxometry diffusion-informed myelin water imaging (MCR-DIMWI) and multi-echo T2-relaxation imaging with compressed sensing (METRICS) to determine myelin water fractions (MWF). Multi-shell diffusion-weighted data were used for diffusion tensor imaging measures and neurite orientation dispersion and density imaging (NODDI) analysis, which estimates neurite density index, orientation dispersion index, and free water fraction. As quantitative MRI measures are age-dependent, ratios between actual and age-expected MRI measures were calculated. We performed the multilevel analysis with subsequent post-hoc and correlation tests to assess differences between groups and clinico-radiological correlations. Results Sixteen control (age range: 2.3–61.3 years, 8 male), 37 VWM (2.4–56.5 years, 20 male), and 14 MLD (2.2–41.7 years, 6 male) subjects were included. Neurite density index and MWF were lower in patients than in controls ( p  < 0.001). Free water fraction was highest in VWM ( p  = 0.01), but similar to controls in MLD ( p  = 0.99). Changes in diffusion tensor imaging measures relative to controls were generally more pronounced in VWM than in MLD. In both patient groups, MCR-DIMWI MWF correlated strongest with clinical measures. Conclusion Quantitative MRI correlates to clinical measures and yields differential profiles in VWM and MLD, in line with differences in neuropathology. Key Points Question Can quantitative MRI reflect known neuropathological differences and correlate with clinical scores for these leukodystrophies ? Finding Quantitative MRI measures, e.g., MWF, neurite density index, and free water fraction differ between leukodystrophies and controls, in correspondence to known histological differences . Clinical relevance MRI techniques producing quantitative, biologically-specific, measures regarding the health of myelin and axons deliver more comprehensive information regarding pathological changes in leukodystrophies than current approaches, and are thus viable tools for monitoring patients and providing clinical trial outcome measures .

Metachromatic leukodystrophy (MLD) is a genetic lysosomal disease. Here, we investigated the role of prosaposin (PSAP) gene mutations in MLD. This current case report describes a female patient who presented with motor development regression at two years and five months of age. The symptoms included difficulty walking, loss of ambulation, increased muscle tension, limb pain, and intentional tremors. Brain magnetic resonance imaging revealed potential white matter lesions, while electromyography indicated neurogenic damage in both lower limbs. Gesell assessment showed severe motor retardation, along with mild retardation in adaptability, speech, and social communication. Whole exome sequencing analysis identified a homozygous mutation in the PSAP gene, specifically c.643A>G, resulting in the amino acid change p.N215D. Immunofluorescence assays of cultured cells indicated no impact on the PSAP protein lysosomal localization, but the mutation was associated with a decreased lysosomal pH and reduced cathepsin D activity. Transmission electron microscopy revealed changes in lysosome morphology and abnormal protein aggregation. These findings suggest that the PSAP c.643A>G (p.N215D) mutation may be a causal factor for MLD in this patient. This discovery may provide new insights into the genetic basis and pathophysiological mechanisms of MLD.

Metachromatic leukodystrophy (MLD) is a rare leukoencephalopathy caused by pathogenic mutations in the ARSA gene. It manifests as severe motor symptoms, mental problems, and sometimes, seizures. We aimed to investigate the phenotypic manifestations and genetic causes of MLD in an Iranian family. We present the case of a 3-year-old girl who presented with hypotonia, muscular atrophy, and seizures. Neurological and neuromuscular examinations were performed to evaluate clinical characteristics. Whole exome sequencing (WES) was used to detect disease-causing variants. In silico analysis was performed to predict the pathogenicity of this variant. GROMACS software was utilized for molecular dynamic simulation (MDS). Neurological studies revealed marked slowing of motor conduction velocities and an increased motor unit action potential duration. Brain MRI scan revealed white matter abnormalities. By applying WES, we identified a novel homozygous missense variant (NM_000487.6, c.938G > C, p.R313P) in ARSA. Direct sequencing identified this homozygous variant in her asymptomatic younger sister, whereas both parents carried a heterozygous variant. This mutation has not been reported in genetic databases or in literature. In silico analysis predicted that any variation in this DNA position would cause disease, as it is highly conserved. The c.938G > C variant was classified as a pathogenic variant according to ACMG/AMP guidelines. MDS analysis indicated that c.938G > C had a significant impact on both the structure and stabilization of ARSA, ultimately resulting in impaired protein function. The identification of this variant expands the spectrum of ARSA gene mutations associated with MLD and highlights the importance of genetic testing for the diagnosis of MLD.

Background Metachromatic leukodystrophy (MLD) is a life-limiting neurodegenerative disease due to pathogenic variants in the ARSA gene. Patients experience severe neurological symptoms, developmental regression, and early death. Aim of the study was to analyze disease burden and healthcare utilization in different stages of the disease in children with late infantile and juvenile MLD in Germany. Methods Out of a nationwide total cohort study (TC) (n = 83), we undertook telephone interviews in a representative follow-up cohort (FC) defined by advanced disease stages (n = 19). The FC allowed detailed long-term data of the disease in addition to cross-sectional data of the TC. Results Nearly all patients showed spasticity, truncal hypotonia and dysphagia, and about half of the patients developed epilepsy. Most children required special education; none finished regular school. Analysis of the FC showed that neuronal intestinal burden was extensive, including obstipation (57%), micturition problems (47%), and tube feeding (63%). Gallbladder polyposis was seen in 52%. General well-being did not strongly correlate with motor function, whereas pain was associated with reduced well-being. Baclofen, Omeprazole, Vigabatrin and Polyethyleneglycol were the most frequently used drugs. Patients took up to 15 different drugs daily. Altogether, 127 hospitalisations (485 treatment days) were registered in the FC (median age 9 years, median one inpatient stay per patient per year). Diagnostic procedures were main reasons for hospitalization (29 hospitalizations, 128 treatment days), and accounted for the main burden for families (68%). The median use of 15 different devices (maximum 29) throughout life illustrated a high burden of the disease. During disease course, there was a change from more “active” devices (e.g., walker) to more “passive” devices (e.g., form seat). Physical therapy was the most relevant therapy in advanced disease stages (100%), while occupational therapy or speech therapy primarily were used in early disease stages. State welfare benefits, home- and palliative care were used broadly. Conclusion Diagnostic and treatment routine pathways and sociomedical support in MLD require extensive resources. We provide detailed cross-sectional and long-term data of MLD-associated disease burden in different stages of disease. This data may serve as a reference when analyzing disease- and healthcare burden also after gene-/stem cell-therapy. 

Metachromatic leukodystrophy (MLD) is a demyelinating lysosomal storage disorder for which new treatments are urgently needed. We previously showed that transplantation of gene-corrected hematopoietic stem progenitor cells (HSPCs) in presymptomatic myeloablated MLD mice prevented disease manifestations. Here we show that HSC gene therapy can reverse neurological deficits and neuropathological damage in affected mice, thus correcting an overt neurological disease. The efficacy of gene therapy was dependent on and proportional to arylsulfatase A (ARSA) overexpression in the microglia progeny of transplanted HSPCs. We demonstrate a widespread enzyme distribution from these cells through the CNS and a robust cross-correction of neurons and glia in vivo. Conversely, a peripheral source of enzyme, established by transplanting ARSA-overexpressing hepatocytes from transgenic donors, failed to effectively deliver the enzyme to the CNS. These results indicate that the recruitment of gene-modified, enzyme-overexpressing microglia makes the enzyme bioavailable to the brain and makes therapeutic efficacy and disease correction attainable. Overall, our data provide a strong rationale for implementing HSPC gene therapy in MLD patients.

ObjectiveTo determine whether proton magnetic resonance spectroscopic imaging is useful in predicting clinical course of patients with metachromatic leukodystrophy (MLD), an inherited white matter disorder treatable with haematopoietic cell transplantation (HCT).Methods21 patients with juvenile or adult MLD (12 HCT-treated) were compared with 16 controls in the same age range. Clinical outcome was determined as good, moderate or poor. Metabolites were quantified in white matter, and significance of metabolite concentrations at baseline for outcome prediction was assessed using logistic regression analysis. Evolution of metabolic changes was assessed for patients with follow-up examinations.ResultsIn this retrospective study, 16 patients with baseline scans were included, 5 with good, 3 with moderate and 8 with poor outcome, and 16 controls. We observed significant group differences for all metabolite concentrations in white matter (p<0.001). Compared with controls, patients had decreased N-acetylaspartate and glutamate, and increased myo-inositol and lactate, most pronounced in patients with poor outcome (post hoc, all p<0.05). Logistic regression showed complete separation of data. Creatine could distinguish poor from moderate and good outcome, the sum of glutamate and glutamine could distinguish good from moderate and poor outcome, and N-acetylaspartate could distinguish all outcome groups. For 13 patients (8 with baseline scans), one or more follow-up examinations were evaluated, revealing stabilisation or even partial normalisation of metabolites in patients with moderate and good outcome, clearly visible in the ratio of choline/N-acetylaspartate.ConclusionIn MLD, quantitative spectroscopic imaging at baseline is predictive for outcome and aids in determining eligibility for HCT.