Leukocyte and Dried Blood Spot Arylsulfatase A Assay by Tandem Mass Spectrometry.

Liquid chromatography-tandem mass spectrometry (LC-MS/MS) assays were developed to measure arylsulfatase A (ARSA) activity in leukocytes and dried blood spots (DBS) using deuterated natural sulfatide substrate. These new assays were highly specific and sensitive. Patients with metachromatic leukodystrophy (MLD) and multiple sulfatase deficiency (MSD) displayed a clear deficit in the enzymatic activity and could be completely distinguished from normal controls. The leukocyte assay reported here will be important for diagnosing MLD and MSD patients and for monitoring the efficacy of therapeutic treatments. ARSA activity was measured in DBS for the first time without an antibody. This new ARSA DBS assay can serve as a second-tier test following the sulfatide measurement in DBS for newborn screening of MLD. This leads to an elimination of most of the false positives identified by the sulfatide assay.

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.

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.

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.

Early progression of Krabbe disease in patients with symptom onset between 0 and 5 months.

BACKGROUND: Krabbe disease is a rare neurological disorder caused by a deficiency in the lysosomal enzyme, ß-galactocerebrosidase, resulting in demyelination of the central and peripheral nervous systems. If left without treatment, Krabbe disease results in progressive neurodegeneration with reduced quality of life and early death. The purpose of this prospective study was to describe the natural progression of early onset Krabbe disease in a large cohort of patients. METHODS: Patients with early onset Krabbe disease were prospectively evaluated between 1999 and 2018. Data sources included diagnostic testing, parent questionnaires, standardized multidisciplinary neurodevelopmental assessments, and neuroradiological and neurophysiological tests. RESULTS: We evaluated 88 children with onset between 0 and 5 months. Median age of symptom onset was 4 months; median time to diagnosis after onset was 3 months. The most common initial symptoms were irritability, feeding difficulties, appendicular spasticity, and developmental delay. Other prevalent symptoms included axial hypotonia, abnormal deep tendon reflexes, constipation, abnormal pupillary response, scoliosis, loss of head control, and dysautonomia. Results of nerve conduction studies showed that 100% of patients developed peripheral neuropathy by 6 months of age. Median galactocerebrosidase enzyme activity was 0.05 nmol/h/mg protein. The median survival was 2 years. CONCLUSIONS: This is the largest prospective natural history study of Krabbe disease. It provides a comprehensive description of the disease during the first 2 years of life. With recent inclusion of state mandated newborn screening programs and promising therapeutic interventions, enhancing our understanding of disease progression in early onset Krabbe disease will be critical for developing treatments, designing clinical trials, and evaluating outcomes.