ImportanceLeukodystrophies are a heterogeneous group of genetic disorders affecting the white matter of the brain, often presenting with overlapping clinical features but differing in neuroanatomical involvement. There is a critical need for quantitative tools to characterize disease burden and support diagnosis, severity stratification, and clinical trial readiness.ObjectiveTo characterize shared and distinct neuroanatomical patterns across six genetically confirmed leukodystrophies using anatomical MRI-derived phenotypes benchmarked against brain growth charts, and to assess the utility of this methodological approach for identifying imaging biomarkers of disease severity.DesignCross-sectional neuroimaging study using retrospective clinical MRI data.SettingMulticenter study incorporating data from the Global Leukodystrophy Initiative Clinical Trials Network (GLIA-CTN) and control data from the Children’s Hospital of Philadelphia.ParticipantsThe study included 434 MRI scan sessions from 274 patients with genetically confirmed leukodystrophies (Pelizaeus-Merzbacher disease, Metachromatic leukodystrophy, Alexander disease, Aicardi-Goutières syndrome, TUBB4A-related leukodystrophies, and POLR3-related leukodystrophy). Control MRI data (7628 scans from 7205 subjects) were drawn from the Scans with Limited Imaging Pathology cohort at the Children’s Hospital of Philadelphia.ExposuresAll MRI scans underwent automated segmentation using deep learning segmentation tools to derive global and regional brain volumes. Normative models of brain development (“brain growth charts”) were generated for the control cohort using generalized additive models for location, scale, and shape. Centile scores were then calculated for leukodystrophy subjects to quantify deviations from typical development.Main Outcomes and MeasuresCentile scores for global and regional brain volumes were compared across leukodystrophy subtypes to identify disease-specific neuroanatomical patterns and to evaluate their potential utility for severity stratification.ResultsDistinct patterns of neuroanatomical deviation were observed across leukodystrophy subtypes. Certain leukodystrophies showed preferential involvement of specific cortical or subcortical regions, while others displayed more diffuse volume loss. Centile scores demonstrated potential for differentiating disease subtypes and stratifying individuals by severity. Preliminary longitudinal data suggest centile scores may also track progression over time.Conclusions and RelevanceThis study demonstrates the feasibility and utility of MRI profiling of individuals with leukodystrophy using anatomical MRI-derived phenotypes benchmarked against brain growth charts. The approach enables data-driven, quantitative characterization of structural brain abnormalities, offering a scalable method for phenotyping, diagnosis, and future use in clinical trials.Key PointsQuestionIn genetically confirmed leukodystrophies, can anatomical MRI measurements benchmarked against brain growth charts identify neuroanatomical patterns that correlate with clinical function and disease severity?FindingsIn this cross-sectional neuroimaging study of six leukodystrophies, imaging-derived quantitative phenotypes benchmarked against brain growth charts revealed neuroanatomical patterns of volume loss consistent with previously-reported qualitative changes for each disorder. These patterns of regional volume loss correlated with measures of clinical function, particularly in POLR3-related leukodystrophy, TUBB4A-related leukodystrophy, and Aicardi-Goutières Syndrome.MeaningBrain growth charts may be a valuable tool for characterizing the patterns of involvement across different leukodystrophies. Furthermore, this approach may facilitate the use of atrophy as a biomarker for assessing disease severity in clinical trials.

HighlightsWhat are the main findings?Siblings of children with life-limiting disease show both adaptation and significant emotional strain in relation to their family life with a seriously ill sibling.Sibling support occurs across multiple everyday contexts, such as from assistants or through aids in the family home, from family, friends, health care, and school. However, support provided to siblings is often uneven, fragmented, or insufficient.What are the implications of the main findings?Siblings must be systematically included in pediatric palliative care from an early stage of the child’s life-limiting illness and palliative care.Care needs to be family-centered, provided within the everyday life of the family and coordinated across contexts.Background/Objectives: Siblings of children with the life-limiting disease Metachromatic Leukodystrophy (MLD) are growing up witnessing rapid disease progression and death, affecting development and psychological wellbeing. Family-centred palliative care should include sibling support, but research on sibling needs is scarce. This semi-structured interview study aims to describe parents’ perceptions of siblings’ behavioural adaptation, emotional reactions, and support needs. Methods: Seven parents recruited from a national resource centre for rare disorders participated in semi-structured interviews that were audiotaped and transcribed. Content analysis was used to identify recurrent themes. Results: Siblings were described as more mature, patient, caring, appreciative, and sociable than other children due to life with the ill child. Expressions of love and concern, fear, sadness and sorrow, anger, and hope were described. Parents described how sibling support implies strengthening close family relations and providing resources at home, external support, and information. Conclusion: This study shows that sibling support involves all instances surrounding the family and ill child, and that a family-centred, trauma-sensitive approach is needed.

Metachromatic leukodystrophy (MLD) is arare lysosomal storage disorder characterized by progressive white matter demyelination. Quantification of demyelinated white matter on MRI-typically expressed as the demyelination load-serves as akey imaging biomarker of disease burden, enabling objective monitoring beyond visual rating scales. However, current semi-automated pipelines are limited by manual interaction, pediatric brain variability, and differences in MRI acquisition. This study aimed to develop and validate aself-configuring convolutional neural network (CNN) for automated segmentation of demyelinated white matter in MLD and to compare its performance with aconventional semi-automated method across heterogeneous MRI datasets. An nnU-Net was trained on 189 3D T1- and axial T2-weighted scans from 35MLD patients using visually controlled conventional masks as ground truth. Independent testing was performed on 130 scans (73high-resolution 3D, 57lower-resolution 2D T1-weighted) from 49patients. Performance was assessed by Dice coefficient, Bland-Altman bias, correlation with Gross Motor Function Classification (GMFC-MLD), MLD MRI severity score, longitudinal consistency, and qualitative review of outliers. CNN-based segmentation showed strong spatial agreement with the reference method, with amedian Dice coefficient of 0.82 for 3D T1-weighted scans and 0.75 for 2D scans. Volumetric bias was minimal on Bland-Altman analysis. CNN-derived demyelination load correlated significantly with motor impairment (rS = 0.38 for 3D and r = 0.56 for 2D; both p < 0.001) and showed astronger association with the MLD MRI severity score than conventional segmentation (3D: rS = 0.48 vs. 0.28; 2D: rS = 0.83 vs. 0.29). Correlations with clinical status were slightly lower (CNN: rS = 0.38, p < 0.001; conventional: (rS = 0.26, p < 0.025)) Longitudinal analyses demonstrated stable, monotonic changes over time, and qualitative review revealed fewer boundary misclassifications. The nnU-Net enables fast, reproducible, and clinically meaningful segmentation of demyelinated white matter in MLD. It generalizes across MRI protocols, correlates with motor function, and offers ascalable tool for standardized biomarker extraction in clinical trials and other leukodystrophies.

This study evaluated whether multiparametric MRI parameters at the time of hematopoietic stem cell transplantation (HSCT) can predict long-term clinical outcomes in juvenile metachromatic leukodystrophy (MLD), and assessed their longitudinal evolution over extended follow-up. In this retrospective, registry-based cohort study, fifteen children with juvenile MLD underwent a comprehensive MRI protocol at HSCT including quantitative demyelination load, diffusion-weighted imaging (DWI), MR spectroscopy (MRS), and volumetric analysis. Patients were followed clinically for a median of five years and retrospectively stratified into stabilized, moderately progressive, or severely progressive trajectories based on motor function (GMFC-MLD) and cognitive performance. Baseline imaging metrics and their changes over time were compared across outcome groups. Higher baseline demyelination load, increased apparent diffusion coefficient in the posterior limb of the internal capsule, and lower MRS metabolite ratios (NAA/Cr and NAA/Cho) were significantly associated with a severely progressive clinical course. In contrast, baseline MRI severity score and brain volumes at HSCT were not predictive of outcome. Longitudinal analysis demonstrated consistent group differences in visually assessable MRI parameters, including lesion burden, grey matter volume, total brain volume, and MRI severity score, which were most pronounced in patients with unfavorable clinical trajectories. Diffusion and spectroscopy measures showed region- and parameter-specific longitudinal effects but showed weaker and less consistent group separation compared with volumetric and lesion-based measures. Notably, baseline MRS metrics allowed retrospective stratification of patients with mild motor impairment (GMFC-MLD = 1) into distinct outcome groups, supporting early prognostic value. Multiparametric MRI at the time of HSCT provides complementary prognostic and longitudinal information in juvenile metachromatic leukodystrophy. Baseline microstructural and metabolic abnormalities are associated with long-term clinical trajectories, whereas longitudinal disease evolution after HSCT is more consistently captured by volumetric and lesion-based MRI markers. These findings support the use of advanced MRI biomarkers for early risk stratification and subsequent monitoring and warrant further evaluation, including in gene therapy-treated cohorts.

Two Novel Mutations in the PSAP Gene Causing a Metachromatic Leukodystrophy (MLD)-like Phenotype and a Review of the Literature.

1558 Histologic Characterization of Gallbladder Pathology in Metachromatic Leukodystrophy

1553 First Molecular Characterization of Polypoid Lesions of the Gallbladder in Late Infantile Metachromatic Leukodystrophy

Metachromatic leukodystrophy (MLD) in France: the views of family caregivers on the diagnosis of the disease, its daily burden on their child, and the whole family.

Gallbladder abnormalities in metachromatic leukodystrophy: Preliminary analysis in patients treated with atidarsagene autotemcel (autologous hematopoietic stem cell gene therapy) and untreated patients

Dried blood spot arylsulfatase A enzyme analysis for second-tier newborn screening and diagnosis of metachromatic leukodystrophy

Duchenne Muscular Dystrophy and Metachromatic Leukodystrophy Added to the Newborn Screening Program.

Caregiver treatment preferences in late infantile and early juvenile metachromatic leukodystrophy: A best-worst scaling study

Rationale:Multiple system atrophy (MSA) is primarily a sporadic neurodegenerative disorder, and a positive family history is considered against the diagnosis. While rare familial clusters are reported, they pose a significant diagnostic challenge. This report describes 2 cousins with phenotypically classic MSA who underwent genetic testing to investigate a potential shared etiology, leading to a diagnosis of a rare MSA mimic.Patient concerns:Case 1: a 77-year-old male presented with Parkinsonism (bradykinesia, resting tremor) and neurogenic orthostatic hypotension. Case 2: a 55-year-old female, case 1’s 1st cousin, presented with progressive limb ataxia, dysarthria, and neurogenic orthostatic hypotension. Both patients reported a poor therapeutic response to levodopa and a progressive decline in functional mobility.Diagnoses:Initially, case 1 was diagnosed with clinically probable MSA with predominant Parkinsonism, and case 2 was diagnosed with clinically probable MSA with predominant cerebellar ataxia (MSA-C). However, post-genetic analysis, case 1 was definitively diagnosed with late-onset metachromatic leukodystrophy (MLD). Case 2 remained clinically classified as MSA-C as no significant genetic variants were identified.Interventions:Clinical evaluation and levodopa trials were conducted for both patients. To investigate the suspected familial MSA cluster, whole-genome sequencing was performed for both individuals to identify shared pathogenic variants.Outcomes:Whole-genome sequencing identified biallelic pathogenic mutations in the arylsulfatase A gene in case 1, confirming MLD. No shared genetic etiology was found in case 2. The discovery of MLD in case 1 provided an alternative metabolic explanation for his symptoms, thereby refuting the initial hypothesis of a shared familial MSA link between the 2 cousins.Lessons:This case highlights that late-onset MLD can closely mimic the clinical phenotype of MSA. Clinicians should maintain a high index of suspicion when encountering familial MSA. A comprehensive genetic evaluation is essential in such cases to exclude metabolic or hereditary mimics before concluding a rare familial presentation of a typically sporadic synucleinopathy.

Metachromatic leukodystrophy (MLD) is an autosomal recessive genetic disorder caused by arylsulfatase A (ARSA) deficiency. Patients with MLD exhibit a high prevalence of gallbladder polyps and intestinal metaplasia. Although these precancerous lesions may progress to malignancy over time, gallbladder cancer is rarely diagnosed in children. Here, we present a case of gallbladder mucinous adenocarcinoma in a 5-year-old child, detailing its clinical, imaging, pathological, and genetic characteristics. To our knowledge, this is one of the earliest documented instances of pediatric gallbladder mucinous adenocarcinoma in MLD. A 5-year-old male patient was admitted with a recurrent intermittent epigastric pain for over six months. Imaging examinations revealed an enlarged gallbladder and thickened gallbladder wall. The patient underwent cholecystectomy, and histopathological analysis confirmed mucinous adenocarcinoma with low-grade intraepithelial neoplasia. A low frequency (6.31%) of somatic KMT2C gene mutations (c.2922A > T, p.L974F) was detected in the tumor tissue. Ten months later, the patient was readmitted due to the onset of abnormal neuropsychiatric behaviors and significant regression in both cognitive and motor function. Brain MRI revealed multiple, bilateral, symmetrical abnormal signals within the cerebral white matter. Whole exome sequencing (WES) identified a homozygous missense variant (c.640G > A; p.Ala214Thr) in the ARSA gene. A diagnosis of MLD was established bases on clinical and molecular findings. Pediatric gallbladder cancer is extremely rare. Although the role of low-frequency (6.31%) KMT2C variant in carcinogenesis is uncertain. When accompanied by neurological symptoms, there is high suspicion for an underlying genetic etiology. Radiological imaging plays a critical role in providing indications for the diagnosis of leukodystrophy. And genetic testing is helpful in detecting germline variations and somatic mutations in tumor tissues.

Intracranial volume (ICV) is often used as normalization factor in volumetrics and considered to be stable in young adults. We noticed thick skulls on MRI scans of leukodystrophy patients, suggesting potentially changing skull morphology. In this study we aimed to quantify skull thickness and ICV in metachromatic leukodystrophy (MLD) patients and people with multiple sclerosis (pwMS). We retrospectively analyzed single-center cross-sectional and longitudinal MRI scans. Skull thickness and ICV were determined using automated segmentation techniques. Participants included MLD (n=32, 11 male, scans=136, median age first scan=14.1 [IQR 7.9-25.7] years), MS (n=232, 78 male, median age first scan=47.3 [IQR 39.6-55.4] years, scans=431), and controls (n=139, 67 male, median age first scan=30.7 [IQR 10.7-48.9] years, scans=283). Both ICV and skull thickness showed natural growth in young controls. In young MLD participants, ICV decreased (-18.8±22.4mL/year, p<0.001). Above age 20, ICV and skull thickness remained stable in controls. In comparison to controls, we observed ICV loss in MLD participants (-4.01±8.29mL/year, p<0.001) and in pwMS (-2.99±2.69mL/year, p<0.001), as well as skull thickening (MLD: 0.16±0.14mm/year, p<0.001, pwMS: 0.04±0.09mm/year, p=0.009). In adult patient groups, negative correlations were found between ICV and skull thickness (MLD: -19.24mL/mm, p<0.001, pwMS: -11.56mL/mm, p<0.001), but not in controls (p=0.11). Despite limitations due to scanner variations, segmentation reliability and absence of validation against ground truth, these findings demonstrate a reduction in ICV in pathologies, already in young adulthood. Although the observed changes are small, they may lead to underestimations of atrophy when using ICV as a normalization factor.

A significant number of inherited neurodegenerative metabolic diseases (NMDs) arise from altered lipid metabolism, including impaired degradation of sphingolipids and dysfunction in organelle-related machineries involved in lipid processing and trafficking. These lipid dysregulations profoundly impact cellular membranes, signaling pathways, and myelin integrity, contributing to the complex and multisystemic clinical phenotypes characteristic of NMD, which often complicate diagnosis and delay treatment initiation. Here, we present a high-throughput, multiplex LC-MS/MS method for the analysis of an extended panel of NMD biomarkers in plasma and dried blood spots. One-step sample extraction and targeted LC-MS/MS acquisitions in positive and negative ionization allowed the simultaneous measurement of 13 diagnostic biomarkers associated with GM1 and GM2 gangliosidosis, Fabry, Gaucher, and Krabbe diseases, acid sphingomyelinase deficiency, Niemann-Pick disease type C, X-linked adrenoleukodystrophy, peroxisomal biogenesis disorders (Zellweger syndrome), metachromatic leukodystrophy, and mental retardation, enteropathy, deafness, neuropathy, ichthyosis, keratoderma (MEDNIK)/MEDNIK-like syndromes, a disorder of cellular trafficking. The method was analytically and clinically validated, confirming the diagnosis of all targeted NMDs in samples from 89 patients. Additionally, the method allowed the differentiation of X-linked adrenoleukodystrophy from peroxisomal biogenesis disorder and revealed the elevation of C18- and C16-sulfatides in Krabbe disease and MEDNIK syndrome, respectively. This multiplex assay enhances diagnostic efficiency and expands the discovery of novel biomarkers, enabling the quantification of diagnostic markers for a wide range of NMDs. The method is suitable for diagnosis of NMD, as a first- or second-tier test in neonatal screening, as confirmatory testing of variant of unknown significance in genetic panels and for longitudinal monitoring in treatable diseases.

Metachromatic leukodystrophy is an autosomal recessive neurodegenerative disease. The underlying mechanism of disease is the lack of arylsulphatase A, which leads to the accumulation of sulphated glycosphingolipids. Three forms of disease are recognized based on clinical onset, including infantile, juvenile, and adult forms. Until recently, metachromatic leukodystrophy was untreatable. In this article, we present the cases of a sister and brother with the late infantile form. The female was diagnosed when the disease was at an advanced stage, and thus, was treated palliatively. Her younger brother was diagnosed at the pre-symptomatic stage and experimental genetic treatment was conducted, which markedly Improved the course of disease.

This study evaluated intravenous administration of allogeneic mesenchymal stem cells (MSCs) transduced with AAV9-ARSA to pigs. The MSCs were modified to overexpress human arylsulfatase A (ARSA). Thirty-five days after treatment, ARSA activity significantly increased in CNS tissues. No hepatotoxicity or systemic inflammation was observed. The results confirm the safety and efficacy of this MSC-based gene therapy for metachromatic leukodystrophy (MLD).

Juvenile metachromatic leukodystrophy caused by a rare genetic mutation.

IntroductionSaposin B deficiency is an ultrarare lysosomal disorder caused by biallelic mutations in the PSAP gene. Although it clinically resembles classical arylsulfatase A (ARSA)-deficient metachromatic leukodystrophy (MLD), ARSA activity remains biochemically normal. Fewer than 30 genetically confirmed patients have been reported to date.Patient PresentationWe describe 2 pediatric patients with homozygous PSAP gene mutations. Both presented with progressive neurodegeneration, spastic quadriparesis, demyelinating peripheral neuropathy, and radiologic findings consistent with MLD. The first patient harbored a canonical splice-site variant (c.577-1G>T), whereas the second carried a recurrent missense mutation (p.Cys241Ser). Notably, the first patient also had a PMP22 duplication consistent with coexisting CMT1A. Despite preserved ARSA activity, both patients fulfilled clinical and imaging criteria for MLD. Abdominal imaging revealed gallbladder sludge in both patients, with additional biliary tract dilation in one. These hepatobiliary findings have not been previously reported in genetically confirmed saposin B deficiency, broadening the known phenotypic spectrum.ConclusionThese patients underscore the importance of PSAP gene sequencing in MLD-like presentations with normal ARSA activity and suggest that hepatobiliary involvement may be an underrecognized feature of saposin B-related MLD.