Developmental delay can precede neurologic regression in early onset metachromatic leukodystrophy.

OBJECTIVE: Metachromatic leukodystrophy (MLD) is a rare neurodegenerative disorder. Emerging therapies are most effective in the presymptomatic phase, and thus defining this window is critical. We hypothesize that early development delay may precede developmental plateau. With the advent of presymptomatic screening platforms and transformative therapies, it is essential to define the onset of neurologic disease. METHODS: The specific ages of gain and loss of developmental milestones were captured from the medical records of individuals affected by MLD. Milestone acquisition was characterized as: on target (obtained before the age limit of 90th percentile plus 2 standard deviations compared to a normative dataset), delayed (obtained after 90th percentile plus 2 standard deviations), or plateau (skills never gained). Regression was defined as the age at which skills were lost. LI-MLD was defined by age at onset before 2.5 years. RESULTS: Across an international cohort, 351 subjects were included (n = 194 LI-MLD subcohort). The median age at presentation of the LI-MLD cohort was 1.4 years (25th-75th %ile: 1.0-1.5). Within the LI-MLD cohort, 75/194 (39%) had developmental delay (or plateau) prior to MLD clinical presentation. Among the LI-MLD cohort with a minimum of 1.5 years of follow-up (n = 187), 73 (39.0%) subjects never attained independent ambulation. Within LI-MLD + delay subcohort, the median time between first missed milestone target to MLD decline was 0.60 years (maximum distance from delay to onset: 1.9 years). INTERPRETATION: Early developmental delay precedes regression in a subset of children affected by LI-MLD, defining the onset of neurologic dysfunction earlier than previously appreciated. The use of realworld data prior to diagnosis revealed an early deviation from typical development. Close monitoring for early developmental delay in presymptomatic individuals may help in earlier diagnosis with important consequences for treatment decisions.

Adeno-associated virus-mediated gene therapy in a patient with Canavan disease using dual routes of administration and immune modulation.

Gene replacement therapy is a rational therapeutic strategy and clinical intervention for neurodegenerative disorders like Canavan disease, a leukodystrophy caused by biallelic mutations in the aspartoacylase (ASPA) gene. We aimed to investigate whether simultaneous intravenous (i.v.) and intracerebroventricular (i.c.v.) administration of rAAV9-CB6-ASPA provides a safe and effective therapeutic strategy in an open-label, individual-patient, expanded-access trial for Canavan disease. Immunomodulation was given prophylactically prior to adeno-associated virus (AAV) treatment to prevent an immune response to ASPA or the vector capsid. The patient served as his own control, and change from baseline was assessed by clinical pathology tests, vector genomes in the blood, antibodies against ASPA and AAV capsids, levels of cerebrospinal fluid (CSF) N-acetylaspartate (NAA), brain water content and morphology, clinical status, and motor function tests. Two years post treatment, the patient's white matter myelination had increased, motor function was improved, and he remained free of typical severe epilepsy. NAA level was reduced at 3 months and remained stable up to 4 years post treatment. Immunomodulation prior to AAV exposure enables repeat dosing and has prevented an anti-transgene immune response. Dual-route administration of gene therapy may improve treatment outcomes.

Improved Brain Pathology and Progressive Peripheral Neuropathy in a 15 Year Old Survivor of Infantile Krabbe Disease Treated With Umbilical Cord Transplantation.

Objective: Krabbe disease is a fatal leukodystrophy caused by deficiency in galactocerebrosidase enzyme activity. The only currently available therapy is hematopoietic stem cell transplantation with bone marrow or umbilical cord blood (UCBT), which leads to increased lifespan and functional abilities when performed in the preclinical stage. While stabilization of white matter disease has been seen on serial MRI studies, neuropathological changes following transplantation have not been documented so far. Materials and Methods: We report the first postmortem examination of a 15-year-old female patient with infantile Krabbe disease after UCBT in infancy. Results: In contrast to an untreated Krabbe disease brain, which showed severe myelin and oligodendrocyte loss with occasional globoid cells, the transplanted brain displayed markedly improved myelin preservation, but not reaching normal myelination levels. Consistent with the transplanted patient's clinical presentation of pronounced deficits in gross motor skills, corticospinal tracts were most severely affected. No globoid cells or evidence of active demyelination were observed in the central nervous system, indicative of at least partially successful functional restoration. This was corroborated by the identification of male donor-derived cells in the brain by in situ hybridization. Unlike the observed disease stabilization in the central nervous system, the patient experienced progressive peripheral neuropathy. While diminished macrophage infiltration was seen postmortem, peripheral nerves exhibited edema, myelin and axon loss and persistent Schwann cell ultrastructural inclusions. Conclusion: Umbilical cord blood transplantation was able to alter the natural disease progression in the central but less so in the peripheral nervous system, possibly due to limited cross-correction of Schwann cells.

ß-Galactosylceramidase Deficiency Causes Upregulation of Long Pentraxin-3 in the Central Nervous System of Krabbe Patients and Twitcher Mice.

Globoid cell leukodystrophy (GLD), or Krabbe disease, is a neurodegenerative sphingolipidosis caused by genetic deficiency of lysosomal ß-galactosylceramidase (GALC), characterized by neuroinflammation and demyelination of the central (CNS) and peripheral nervous system. The acute phase protein long pentraxin-3 (PTX3) is a soluble pattern recognition receptor and a regulator of innate immunity. Growing evidence points to the involvement of PTX3 in neurodegeneration. However, the expression and role of PTX3 in the neurodegenerative/neuroinflammatory processes that characterize GLD remain unexplored. Here, immunohistochemical analysis of brain samples from Krabbe patients showed that macrophages and globoid cells are intensely immunoreactive for PTX3. Accordingly, Ptx3 expression increases throughout the course of the disease in the cerebrum, cerebellum, and spinal cord of GALC-deficient twitcher (Galctwi/twi) mice, an authentic animal model of GLD. This was paralleled by the upregulation of proinflammatory genes and M1-polarized macrophage/microglia markers and of the levels of PTX3 protein in CNS and plasma of twitcher animals. Crossing of Galctwi/twi mice with transgenic PTX3 overexpressing animals (hPTX3 mice) demonstrated that constitutive PTX3 overexpression reduced the severity of clinical signs and the upregulation of proinflammatory genes in the spinal cord of P35 hPTX3/Galctwi/twi mice when compared to Galctwi/twi littermates, leading to a limited increase of their life span. However, this occurred in the absence of a significant impact on the histopathological findings and on the accumulation of the neurotoxic metabolite psychosine when evaluated at this late time point of the disease. In conclusion, our results provide the first evidence that PTX3 is produced in the CNS of GALC-deficient Krabbe patients and twitcher mice. PTX3 may exert a protective role by reducing the neuroinflammatory response that occurs in the spinal cord of GALC-deficient animals.

"Atypical" Krabbe disease in two siblings harboring biallelic GALC mutations including a deep intronic variant.

Krabbe disease (KD) is a rare lysosomal storage disorder caused by biallelic pathogenic variants in GALC. Most patients manifest the severe classic early-infantile form, while a small percentage of cases have later-onset types. We present two siblings with atypical clinical and neuroimaging phenotypes, compared to the classification of KD, who were found to carry biallelic loss-of-function GALC variants, including a recurrent 30 kb deletion and a previously unreported deep intronic variant that was identified by mRNA sequencing. This family represents a unique description in the KD literature and contributes to expanding the clinical and molecular spectra of this rare disorder.

Evolving therapies in neuronopathic LSDs: opportunities and challenges.

Lysosomal storage disorders (LSD) are multisystemic progressive disorders caused by genetic mutations involving lysosomal function. While LSDs are individually considered rare diseases, the overall true prevalence of these disorders is likely higher than our current estimates. More than two third of the LSDs have associated neurodegeneration and the neurological phenotype often defines the course of the disease and treatment outcomes. Addressing the neurological involvement in LSDs has posed a significant challenge in the rapidly evolving field of therapies for these diseases. In this review, we summarize current approaches and clinical trials available for patients with neuronopathic lysosomal storage disorders, exploring the opportunities and challenges that have emerged with each of these.

Caregivers' assessment of meaningful and relevant clinical outcome assessments for Sanfilippo syndrome.

OBJECTIVES: Sanfilippo syndrome is a rare multisystem disease with no approved treatments. This study explores caregiver perspectives on the most impactful symptoms and patient-relevant clinical outcomes assessments. The pediatric onset and progressive neurodegenerative nature of Sanfilippo limits use of self-report in clinical research. This study obtains Sanfilippo caregiver data to support the selection of fit-for-purpose and patient-relevant clinical outcome assessments (COAs). METHODS: We conducted an asynchronous online focus group (n = 11) followed by individual interviews with caregivers (n = 19) of children with Sanfilippo syndrome. All participants reported on the impact of disease symptoms and level of unmet treatment need across Sanfilippo symptom domains. Focus group participants reviewed existing assessments relating to 8 symptom domains (15 total assessments) and provided feedback on meaningfulness and relevance. Focus group data were used to reduce the number of assessments included in subsequent interviews to 8 COAs across 7 symptom domains: communication, eating, sleep, mobility, pain, behavior and adapting. Interview respondents provided data on meaningfulness and relevance of assessments. Data were coded using an item-tracking matrix. Data summaries were analyzed by caregivers' responses regarding meaningfulness; relevance to Sanfilippo syndrome; and based on caregiver indication of missing or problematic subdomains and items. RESULTS: Participants' children were 2-24 years in age and varied in disease progression. Caregivers reported communication and mobility as highly impactful domains with unmet treatment needs, followed closely by pain and sleep. Domains such as eating, adaptive skills, and behaviors were identified as impactful but with relatively less priority, by comparison. Participants endorsed the relevance of clinical outcome assessments associated with communication, eating, sleep, and pain, and identified them as highly favorable for use in a clinical trial. Participants specified some refinements in existing assessments to best reflect Sanfilippo symptoms and disease course. DISCUSSION: The identification of impactful symptoms to treat and relevant and meaningful clinical outcome assessments supports patient-focused drug development. Our results inform targets for drug development and the selection of primary and secondary outcome assessments with high meaningfulness and face validity to Sanfilippo syndrome caregivers. Assessments identified as less optimal might be refined, replaced, or remain if the clinical trial necessitates.

Consensus recommendations for the classification and long-term follow up of infants who screen positive for Krabbe Disease.

OBJECTIVE: To provide updated evidence and consensus-based recommendations for the classification of individuals who screen positive for Krabbe Disease (KD) and recommendations for long-term follow-up for those who are at risk for late onset Krabbe Disease (LOKD). METHODS: KD experts (KD NBS Council) met between July 2017 and June 2020 to develop consensus-based classification and follow-up recommendations. The resulting newly proposed recommendations were assessed in a historical cohort of 47 newborns from New York State who were originally classified at moderate or high risk for LOKD. RESULTS: Infants identified by newborn screening with possible KD should enter one of three clinical follow-up pathways (Early infantile KD, at-risk for LOKD, or unaffected), based on galactocerebrosidase (GALC) activity, psychosine concentration, and GALC genotype. Patients considered at-risk for LOKD based on low GALC activity and an intermediate psychosine concentration are further split into a high-risk or low-risk follow-up pathway based on genotype. Review of the historical New York State cohort found that the updated follow-up recommendations would reduce follow up testing by 88%. CONCLUSION: The KD NBS Council has presented updated consensus recommendations for efficient and effective classification and follow-up of NBS positive patients with a focus on long-term follow-up of those at-risk for LOKD.

Long-term neurodevelopmental outcomes of hematopoietic stem cell transplantation for late-infantile Krabbe disease.

Krabbe disease is a rare neurodegenerative disorder caused by a deficiency in galactocerebrosidase. The only effective treatment is hematopoietic stem cell transplantation (HSCT). Approximately 85% of Krabbe disease cases are the infantile subtypes, among which ∼20% are late infantile. Prior studies have demonstrated that HSCT is effective for early-infantile patients (0-6 months of age) who undergo transplantation while asymptomatic, compared with those receiving transplants while symptomatic. However, no studies evaluated the efficacy of HSCT for late-infantile patients (6-36 months). In this prospective, longitudinal study, patients were evaluated at a single site according to a standardized protocol. Survival analysis was performed using the Kaplan-Meier method. Differences between groups were estimated using mixed regression models to account for within-person repeated measures. Nineteen late-infantile patients underwent HSCT (March 1997 to January 2020). Compared with untreated patients, transplant recipients had a longer survival probability and improved cognitive and language function. Gross and fine motor development were most affected, with variable results. Asymptomatic patients benefitted the most from transplantation, with normal to near-normal development in all domains and some gross motor delays. Among symptomatic patients, those with disease onset at >12 months of age had better cognitive outcomes than untreated patients. Those with disease onset at ≤12 months were comparable to untreated patients. We found that HSCT prolonged the lifespan and improved the functional abilities of late-infantile patients with Krabbe disease, particularly those who underwent transplantation before onset of symptoms. In addition, our findings support prior literature that reclassifies late-infantile Krabbe disease to be symptom onset at 12 to 36 months of age.

Parent Experiences of Sanfilippo Syndrome Impact and Unmet Treatment Needs: A Qualitative Assessment.

INTRODUCTION: Sanfilippo syndrome (MPS III) is a rare, degenerative condition characterized by symptoms impacting cognitive ability, mobility, behavior, and quality of life. Currently there are no approved therapies for this severe life-limiting disease. Integrating patient and caregiver experience data into drug development and regulatory decision-making has become a priority of the Food and Drug Administration and rare disease patient communities. METHODS: This study assesses parents' perceptions of their child's Sanfilippo syndrome disease-related symptoms using a research approach that is consistent with the Center for Drug Evaluation and Research (CDER) guidance. This study was initiated by the Cure Sanfilippo Foundation, and all steps in the research process were informed by a multidisciplinary advisory committee, with an objective of informing biopharmaceutical companies and regulatory agencies. We explored caregiver burden, symptoms with greatest impact, and meaningful but unmet treatment needs. Data were collected from 25 parents through three focus groups and a questionnaire. Transcripts were coded and analyzed using inductive thematic analysis, and descriptive analysis of quantitative data was conducted. RESULTS: Participating parents' children ranged in age from 4 to 36 years. Participants endorsed high caregiving burden across all stages of the disease. Analysis revealed multiple domains of unmet need that impact child and family quality of life, including cognitive-behavioral challenges in communication, relationships, behavior, anxiety, and child safety; and physical health symptoms including sleep, pain, and mobility. Participants reported placing high value on incremental benefits targeting those symptoms, and on a treatment that would slow or stop symptom progression. CONCLUSION: Even modest treatment benefits for Sanfilippo syndrome were shown to be highly valued. Despite high caregiver burden, most parents expressed a willingness to "try anything," including treatments with potentially high risk profiles, to maintain their child's current state.

Fosmetpantotenate Randomized Controlled Trial in Pantothenate Kinase-Associated Neurodegeneration.

BACKGROUND: Pantothenate kinase-associated neurodegeneration (PKAN) currently has no approved treatments. OBJECTIVES: The Fosmetpantotenate Replacement Therapy pivotal trial examined whether treatment with fosmetpantotenate improves PKAN symptoms and stabilizes disease progression. METHODS: This randomized, double-blind, placebo-controlled, multicenter study evaluated fosmetpantotenate, 300 mg oral dose three times daily, versus placebo over a 24-week double-blind period. Patients with pathogenic variants of PANK2, aged 6 to 65 years, with a score ≥6 on the PKAN-Activities of Daily Living (PKAN-ADL) scale were enrolled. Patients were randomized to active (fosmetpantotenate) or placebo treatment, stratified by weight and age. The primary efficacy endpoint was change from baseline at week 24 in PKAN-ADL. RESULTS: Between July 23, 2017, and December 18, 2018, 84 patients were randomized (fosmetpantotenate: n = 41; placebo: n = 43); all 84 patients were included in the analyses. Six patients in the placebo group discontinued treatment; two had worsening dystonia, two had poor compliance, and two died of PKAN-related complications (aspiration during feeding and disease progression with respiratory failure, respectively). Fosmetpantotenate and placebo group PKAN-ADL mean (standard deviation) scores were 28.2 (11.4) and 27.4 (11.5) at baseline, respectively, and were 26.9 (12.5) and 24.5 (11.8) at week 24, respectively. The difference in least square mean (95% confidence interval) at week 24 between fosmetpantotenate and placebo was -0.09 (-1.69 to 1.51; P = 0.9115). The overall incidence of treatment-emergent serious adverse events was similar in the fosmetpantotenate (8/41; 19.5%) and placebo (6/43; 14.0%) groups. CONCLUSIONS: Treatment with fosmetpantotenate was safe but did not improve function assessed by the PKAN-ADL in patients with PKAN. © 2020 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Toward newborn screening of metachromatic leukodystrophy: results from analysis of over 27,000 newborn dried blood spots.

PURPOSE: Metachromatic leukodystrophy (MLD) is a lysosomal storage disorder caused by the deficiency of arylsulfatase A (ARSA), which results in the accumulation of sulfatides. Newborn screening for MLD may be considered in the future as innovative treatments are advancing. We carried out a research study to assess the feasibility of screening MLD using dried blood spots (DBS) from de-identified newborns. METHODS: To minimize the false-positive rate, a two-tier screening algorithm was designed. The primary test was to quantify C16:0-sulfatide in DBS by ultraperformance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The screening cutoff was established based on the results from 15 MLD newborns to achieve 100% sensitivity. The secondary test was to measure the ARSA activity in DBS from newborns with abnormal C16:0-sulfatide levels. Only newborns that displayed both abnormal C16:0-sulfatide abundance and ARSA activity were considered screen positives. RESULTS: A total of 27,335 newborns were screened using this two-tier algorithm, and 2 high-risk cases were identified. ARSA gene sequencing identified these two high-risk subjects to be a MLD-affected patient and a heterozygote. CONCLUSION: Our study demonstrates that newborn screening for MLD is highly feasible in a real-world scenario with near 100% assay specificity.

Pathogenic Variants in GALC Gene Correlate With Late Onset Krabbe Disease and Vision Loss: Case Series and Review of Literature.

Background: Krabbe disease is an autosomal recessive demyelinating disorder resulting from deficiency of the lysosomal enzyme galactocerebrosidase. While blindness is often described as a characteristic finding of the disease, it is more common in the infantile phenotype, where vision loss typically arises in the late stages of disease. In comparison, reports of vision loss in late onset phenotypes are less well-described and may be subject to variation between genotypes. Methods: Charts of Krabbe patients with a confirmed diagnosis, who presented with substantial visual impairment, were retrospectively reviewed from a larger group of 199 Krabbe patients. Assessment of clinical status was obtained through review of neurological evaluations, neurodevelopmental assessments, ophthalmological evaluations, visual evoked potentials (VEP), electroretinogram (ERG), nerve conduction velocity (NCV) studies, auditory brainstem responses (ABR), and brain magnetic resonance imaging. Results: Five late onset patients with Krabbe disease (four juvenile and one late-infantile) were included. Three patients were homozygous for c.956A>G_p.Y319C, one was compound heterozygous for c.296+1G>T and c.956A>G_p.Y319C, and one was compound heterozygous for c.1186C>T_p.R396W and c.1901T>C_p.L634S. All patients were of Asian descent and presented initially with vision impairment. Notably, the patients did not present with marked appendicular spasticity or axial hypotonia and all five reached developmental milestones within the normal time frame. For neurophysiological testing, no patient showed abnormalities in NCV or ABR. However, abnormalities in VEP or ERG were seen in all patients. The one patient who underwent transplantation stabilized following treatment. Conclusions: Depending on their genotype, patients with late onset Krabbe disease may initially present with vision loss. Furthermore, patients with p.L634S and p.Y319C should be closely monitored for changes in vision and VEP. This knowledge will become increasingly important as physicians may otherwise overlook these signs and symptoms when monitoring children identified through newborn screening who have the variants described in this report.

Therapy development for the mucopolysaccharidoses: Updated consensus recommendations for neuropsychological endpoints.

Neurological dysfunction represents a significant clinical component of many of the mucopolysaccharidoses (also known as MPS disorders). The accurate and consistent assessment of neuropsychological function is essential to gain a greater understanding of the precise natural history of these conditions and to design effective clinical trials to evaluate the impact of therapies on the brain. In 2017, an International MPS Consensus Panel published recommendations for best practice in the design and conduct of clinical studies investigating the effects of therapies on cognitive function and adaptive behavior in patients with neuronopathic mucopolysaccharidoses. Based on an International MPS Consensus Conference held in February 2020, this article provides updated consensus recommendations and expands the objectives to include approaches for assessing behavioral and social-emotional state, caregiver burden and quality of life in patients with all mucopolysaccharidoses.

Characterization of Fluid Biomarkers Reveals Lysosome Dysfunction and Neurodegeneration in Neuronopathic MPS II Patients.

Mucopolysaccharidosis type II is a lysosomal storage disorder caused by a deficiency of iduronate-2-sulfatase (IDS) and characterized by the accumulation of the primary storage substrate, glycosaminoglycans (GAGs). Understanding central nervous system (CNS) pathophysiology in neuronopathic MPS II (nMPS II) has been hindered by the lack of CNS biomarkers. Characterization of fluid biomarkers has been largely focused on evaluating GAGs in cerebrospinal fluid (CSF) and the periphery; however, GAG levels alone do not accurately reflect the broad cellular dysfunction in the brains of MPS II patients. We utilized a preclinical mouse model of MPS II, treated with a brain penetrant form of IDS (ETV:IDS) to establish the relationship between markers of primary storage and downstream pathway biomarkers in the brain and CSF. We extended the characterization of pathway and neurodegeneration biomarkers to nMPS II patient samples. In addition to the accumulation of CSF GAGs, nMPS II patients show elevated levels of lysosomal lipids, neurofilament light chain, and other biomarkers of neuronal damage and degeneration. Furthermore, we find that these biomarkers of downstream pathology are tightly correlated with heparan sulfate. Exploration of the responsiveness of not only CSF GAGs but also pathway and disease-relevant biomarkers during drug development will be crucial for monitoring disease progression, and the development of effective therapies for nMPS II.

Reduced-intensity single-unit unrelated cord blood transplant with optional immune boost for nonmalignant disorders.

Children with many inherited nonmalignant disorders can be cured or their condition alleviated by hematopoietic stem cell transplantation (HSCT). Umbilical cord blood (UCB) units are a rapidly available stem cell source and offer great flexibility in HLA matching, allowing nearly uniform access to HSCT. Although reduced-intensity conditioning (RIC) regimens promise decreased treatment-related morbidity and mortality, graft failure and infections have limited their use in chemotherapy-naive patients. We prospectively evaluated a novel RIC regimen of alemtuzumab, hydroxyurea, fludarabine, melphalan, and thiotepa with a single-unit UCB graft in 44 consecutive patients with inborn errors of metabolism, immunity, or hematopoiesis. In addition, 5% of the UCB graft was re-cryopreserved and reserved for cord donor leukocyte infusion (cDLI) posttransplant. All patients engrafted at a median of 15 days posttransplant, and chimerism was >90% donor in the majority of patients at 1-year posttransplant with only 1 secondary graft failure. The incidence of grade II to IV graft-versus-host disease (GVHD) was 27% (95% confidence interval [CI], 17-43) with no extensive chronic GVHD. Overall survival was 95% (95% CI, 83-99) and 85% (95% CI, 64-93) at 1 and 5 years posttransplant, respectively. No significant end-organ toxicities were observed. The use of cDLI did not affect GVHD and showed signals of efficacy for infection control or donor chimerism. This RIC transplant regimen using single-unit UCB graft resulted in outstanding survival and remarkably low rates of graft failure. Implementation of the protocol not requiring pharmacokinetic monitoring would be feasible and applicable worldwide for children with inherited disorders of metabolism, immunity, or hematopoiesis. This trial was registered at www.clinicaltrials.gov as #NCT01962415.

Macrophages Expressing GALC Improve Peripheral Krabbe Disease by a Mechanism Independent of Cross-Correction.

Many therapies for lysosomal storage disorders rely on cross-correction of lysosomal enzymes. In globoid cell leukodystrophy (GLD), mutations in GALC cause psychosine accumulation, inducing demyelination, a neuroinflammatory "globoid" reaction and neurodegeneration. The efficiency of GALC cross-correction in vivo, the role of the GALC substrate galactosylceramide, and the origin of psychosine are poorly understood. Using a novel GLD model, we show that cross-correction does not occur efficiently in vivo and that Galc-deficient Schwann cells autonomously produce psychosine. Furthermore, macrophages require GALC to degrade myelin, as Galc-deficient macrophages are transformed into globoid cells by exposure to galactosylceramide and produce a more severe GLD phenotype. Finally, hematopoietic stem cell transplantation in patients reduces globoid cells in nerves, suggesting that the phagocytic response of healthy macrophages, rather than cross-correction, contributes to the therapeutic effect. Thus, GLD may be caused by at least two mechanisms: psychosine-induced demyelination and secondary neuroinflammation from galactosylceramide storage in macrophages.

Spontaneous Third Ventriculostomy in Krabbe Disease.

INTRODUCTION: Spontaneous third ventriculostomies have been reported in relation to obstructive hydrocephalus and increased intracranial pressure and are most commonly seen as disruption of the floor of the third ventricle. Hydrocephalus has been reported in patients with Krabbe disease; however, it is clinically difficult to monitor for hydrocephalus in patients with Krabbe disease as symptoms of increased intracranial pressure may overlap with symptoms of Krabbe disease. We describe a case series of spontaneous third ventriculostomy and hydrocephalus, likely in response to increased intracranial pressure, in patients with infantile Krabbe disease. METHODS: Brain magnetic resonance images of patients with infantile Krabbe disease were retrospectively analyzed to assess for ventricular size and presence of spontaneous third ventriculostomies. A brain atlas was used to standardize the calculation of ventricular size. Mid-sagittal, T2-weighted images around the third ventricle were assessed for spontaneous third ventriculostomies. Developmental outcomes were measured with a series of standardized and validated tests. RESULTS: Seventy-five patients with infantile Krabbe disease were evaluated. Twelve cases of spontaneous third ventriculostomies were identified. Head circumference (SE = 8.07; P < 0.001) and average ventricular volume were greater (left: SE = 1.47, P < 0.001) in patients with spontaneous third ventriculostomies when compared with patients without spontaneous third ventriculostomies. Patients with spontaneous third ventriculostomies also had more delayed development in adaptive (difference = 0.2, P < 0.01), gross motor (difference = 0.0, P < 0.01), and fine motor (difference = 0.1, P < 0.001) function. CONCLUSIONS: Spontaneous third ventriculostomies, likely in the context of increased intracranial pressure, were identified in patients with Krabbe disease. Although difficult to assess, our study highlights the importance of monitoring for increased intracranial pressure, which can result in spontaneous third ventriculostomies, in patients with infantile Krabbe disease.

The critical role of psychosine in screening, diagnosis, and monitoring of Krabbe disease.

PURPOSE: Newborn screening (NBS) for Krabbe disease (KD) is performed by measurement of galactocerebrosidase (GALC) activity as the primary test. This revealed that GALC activity has poor specificity for KD. Psychosine (PSY) was proposed as a disease marker useful to reduce the false positive rate for NBS and for disease monitoring. We report a highly sensitive PSY assay that allows identification of KD patients with minimal PSY elevations. METHODS: PSY was extracted from dried blood spots or erythrocytes with methanol containing d5-PSY as internal standard, and measured by liquid chromatography-tandem mass spectrometry. RESULTS: Analysis of PSY in samples from controls (N = 209), GALC pseudodeficiency carriers (N = 55), GALC pathogenic variant carriers (N = 27), patients with infantile KD (N = 26), and patients with late-onset KD (N = 11) allowed for the development of an effective laboratory screening and diagnostic algorithm. Additional longitudinal measurements were used to track therapeutic efficacy of hematopoietic stem cell transplantion (HSCT). CONCLUSION: This study supports PSY quantitation as a critical component of NBS for KD. It helps to differentiate infantile from later onset KD variants, as well as from GALC variant and pseudodeficiency carriers. Additionally, this study provides further data that PSY measurement can be useful to monitor KD progression before and after treatment.

General anesthesia safety in progressive leukodystrophies: A retrospective study of patients with Krabbe disease and metachromatic leukodystrophy.

BACKGROUND: Krabbe disease and metachromatic leukodystrophy are leukodystrophies characterized by neurologic degeneration and early death. Patients often require general anesthesia for diagnostic and therapeutic interventions. METHODS: A retrospective review of medical records was conducted for patients with Krabbe disease and metachromatic leukodystrophy receiving general anesthesia at a large children's hospital between 2012 and 2017. Patient complications and American Society of Anesthesiologists Physical Status were recorded for all procedures. The Neurodevelopment in Rare Disorders classification system was created to categorize the severity of the patient's disease progression based on clinical markers. Descriptive and inferential statistics were used to compare: (a) complication rate of affected patients vs the general hospital population; (b) the accuracy of the novel Neurodevelopment in Rare Disorders classification system vs American Society of Anesthesiologists Physical Status regarding the assessment of complication risk; (c) complication rate in patients with hematopoietic stem cell transplantation vs those without transplantation; (d) complication rate in immunosuppressed patients vs nonimmunosuppressed patients; and (e) complication rate of the three most commonly performed procedures. RESULTS: A total of 96 patients underwent 287 procedures. Of these, 11 cases had complications, yielding a rate of 3.8%. This is significantly higher than the overall complication rate at our institution of 0.246%. Statistical analysis showed better correlation between the Neurodevelopment in Rare Disorders classification system and complication rate than American Society of Anesthesiologists Physical Status and complication rate. The system also showed better accuracy in differentiating low-risk and high-risk patients. No statistically significant difference in complication rate was found for patients with transplantation vs those without transplantation or for immunosuppressed vs nonimmunosuppressed patients. Of the three most common procedures, central catheter placement/removal exhibited the highest complication rate. CONCLUSIONS: Although the complication rate for patients with Krabbe disease and metachromatic leukodystrophy is higher than the general population, most complications were mild and self-limiting. These results suggest that, in experienced hands, general anesthesia is well tolerated in most children. Findings show that the Neurodevelopment in Rare Disorders classification system is a better indicator for assessing complication risk in patients with Krabbe and metachromatic leukodystrophy than American Society of Anesthesiologists Physical Status.