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.

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.

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.

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.

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.

A prospective natural history study of Krabbe disease in a patient cohort with onset between 6 months and 3 years of life.

BACKGROUND: Krabbe disease is a rare neurodegenerative disorder caused by a deficiency in the lysosomal enzyme galactocerebrosidase. Patients with Krabbe disease present with a variable disease course depending on their age of onset. The purpose of this prospective cohort study was to characterize the natural progression of Krabbe disease in a large group of patients with disease onset between 6 and 36 months of life who were evaluated with a standardized protocol. METHODS: All patients with Krabbe disease who had onset between 6 and 36 months of age and were prospectively evaluated between 2000 to 2017 were included. Standardized neurodevelopmental, physical, and neurological examinations were performed. Other assessments included neuroradiologic and neurophysiologic tests, enzyme level, cerebrospinal fluid analysis, and GALC pathogenic variants when available. Descriptive statistics were used for analysis. Survival curve was estimated using the Kaplan-Meier method. RESULTS: Thirty-five patients (26 boys, 9 girls) with disease onset between 6 and 36 months of age were evaluated. Median age at symptom onset was 11.5 months, with a median delay of 3.5 months between onset of symptoms and diagnosis. Of the 32 symptomatic patients, 23 presented with initial signs or symptoms of disease between 6 and 12 months of life; nine presented after 12 months. The most common initial signs and symptoms were loss of acquired developmental milestones, irritability, abnormal gait, motor delay, and abnormal muscle tone. The most common magnetic resonance imaging abnormality was increased T2 signal in the periventricular white matter. Nerve conduction velocity results were abnormal for 21 of 24 patients. Patients with onset after 12 months had less peripheral nerve involvement and slower disease progression. Abnormal cerebrospinal fluid protein levels were obtained for 13 of 16 symptomatic children. Protein levels were normal in all asymptomatic children. CONCLUSIONS: Based on our findings, we propose reclassifying the group of patients with onset ≤12 months as infantile and the > 12 month group as late-infantile. Patients with onset > 12 months are more likely to benefit from hematopoietic stem cell transplantation. The proposed change in classifications will allow physicians to improve their ability to recognize and diagnose patients and more precisely assess potential treatment effects after transplantation.

Treatment of brain disease in the mucopolysaccharidoses.

The mucopolysaccharidosis (MPS) disorders are a group of lysosomal storage diseases caused by lysosomal enzyme deficits that lead to glycosaminoglycan accumulation, affecting various tissues throughout the body based on the specific enzyme deficiency. These disorders are characterized by their progressive nature and a variety of somatic manifestations and neurological symptoms. There are established treatments for some MPS disorders, but these mostly alleviate somatic and non-neurological symptoms and do not cure the disease. Patients with MPS I, II, III, and VII can present with neurological manifestations such as neurocognitive decline and behavioral problems. Treatment of these neurological manifestations remains challenging due to the blood-brain barrier (BBB) that limits delivery of therapeutic agents to the central nervous system (CNS). New therapies that circumvent this barrier and target brain disease in MPS are currently under development. They primarily focus on facilitating penetration of drugs through the BBB, delivery of recombinant enzyme to the brain by gene therapy, or direct CNS administration. This review summarizes existing and potential future treatment approaches that target brain disease in MPS. The information in this review is based on current literature and presentations and discussions during a closed meeting by an international group of experts with extensive experience in managing and treating MPS.

Developmental and behavioral aspects of mucopolysaccharidoses with brain manifestations - Neurological signs and symptoms.

The mucopolysaccharidoses (MPS) are a group of rare, inherited lysosomal storage disorders, caused by mutations in lysosomal enzymes involved in the degradation of glycosaminoglycans (GAGs). The resulting accumulation of GAGs in the body leads to widespread tissue and organ dysfunction. The spectrum, severity, and progression rate of clinical manifestations varies widely between and within the different MPS types. In addition to somatic signs and symptoms, which vary between the different MPS disorders, patients with MPS I, II, III, and VII present with significant neurological signs and symptoms, including impaired cognitive abilities, difficulties in language and speech, and/or behavioral and sleep problems. To effectively manage and develop therapies that target these neurological manifestations, it is of utmost importance to have a profound knowledge of their natural history and pathophysiology. This review describes the appearance and progression of neurological signs and symptoms in patients with MPS I, II, and III, based on presentations and discussions among an international group of experts during a meeting on the brain in MPS on April 28-30, 2016, and additional literature searches on this subject.

Developmental outcomes of cord blood transplantation for Krabbe disease: A 15-year study.

OBJECTIVE: To describe long-term outcomes of children with early-infantile Krabbe disease who underwent hematopoietic stem cell transplantation (HSCT) in the first 7 weeks of life. METHODS: In this prospective longitudinal study, evaluations performed at baseline and follow-up included brain imaging, neurodiagnostic tests, and neurobehavioral evaluations. RESULTS: Of the 18 patients in this study (11 girls, 7 boys; mean follow-up 9.5 years, range 4-15), 5 died (3 of peritransplant complications, 1 of a surgical complication unrelated to Krabbe disease, 1 of disease progression). One of the surviving patients has normal cognitive function and 10 continue to develop cognitive skills at a slightly slower rate than normal. All surviving patients continue to gain receptive language skills, with 7 falling within the normal range. Ten patients receive speech therapy, and 2 of these patients require augmentative communication devices. Gross motor development varies widely, but 3 patients can walk independently, and 7 walk with assistive devices. Spasticity ranges from mild to severe, and 12 patients wear orthotics. Fine motor skills are generally preserved. Brain myelination and atrophy stabilized in 8 patients, improved in 4 patients, and worsened in 1 patient. Nerve conduction velocities initially improved but continue to be abnormal in most patients. CONCLUSIONS: The surviving patients function at a much higher level than untreated children or symptomatic children who underwent HSCT. These results show that early HSCT changes the natural history of this disease by improving both lifespan and functional abilities. CLASSIFICATION OF EVIDENCE: This study provides Class IV evidence that for children with early-infantile Krabbe disease, early HSCT improves lifespan and functional abilities.

Early disease progression of Hurler syndrome.

BACKGROUND: Newborn screening for mucopolysaccharidosis type I (MPS I) shows promise to improve outcomes by facilitating early diagnosis and treatment. However, diagnostic tests for MPS I are of limited value in predicting whether a child will develop severe central nervous system disease associated with Hurler syndrome, or minimal or no central nervous system involvement associated with the attenuated phenotypes (Hurler-Scheie and Scheie syndromes). Given that the optimal treatment differs between Hurler syndrome and the attenuated MPS I phenotypes, the absence of a reliable prognostic biomarker complicates clinical decision making for infants diagnosed through newborn screening. Information about the natural history of Hurler syndrome may aid in the management of affected infants, contribute to treatment decisions, and facilitate evaluation of treatment effectiveness and prognosis. Thus, the aim of this study was to characterize the progression and timing of symptom onset in infants with Hurler syndrome. RESULTS: Clinical data from 55 patients evaluated at a single center were retrospectively reviewed. Information about each child's medical history was obtained following a standardized protocol including a thorough parent interview and the review of previous medical records. All patients underwent systematic physical and neurodevelopmental evaluations by a multidisciplinary team. Nearly all patients (98%) showed signs of disease during the first 6 months of life. Common early disease manifestations included failed newborn hearing screen, respiratory symptoms, difficulty latching, and otitis media. Other symptoms such as kyphosis, corneal clouding, cardiac disease, joint restrictions, and enlarged head circumference typically appeared slightly later (median age, 8-10 months). During the first 12 months, gross motor development was the most severely affected area of functioning, and a significant number of patients also experienced language delays. Cognition was typically preserved during this period. CONCLUSIONS: In this large cohort of patients with Hurler syndrome, the vast majority showed signs and symptoms of disease during the first months of life. More research is needed to determine the extent to which early clinical manifestations of MPS I can predict phenotype and treatment outcomes.

Forced deflation pulmonary function test: a novel method to evaluate lung function in infants and young children.

We describe the safety and feasibility of a forced deflation pulmonary function test (dPFT) in infants and young children. Fifty-two dPFT studies were performed in 26 patients (median age, 1.4 years). Forced vital capacity (FVC) and forced expiratory flow (FEF75 ) were normal in all except one case, but respiratory system compliance (Crs) was reduced in 24% patients. There were no significant differences in pre-blood and marrow transplantation FVC, FEF75 , and Crs between those patients who did and those who did not have posttransplant pulmonary complications. A larger study is needed to determine the prevalence and significance of PFT abnormalities in this age group.

Clinical management of Krabbe disease.

Krabbe disease (KD) is a rare neurodegenerative disorder caused by mutations in the gene encoding the galactocerebrosidase enzyme. The early- and late-infantile subtypes, which are the most common forms of the disease, are rapidly progressive and lead to early death, whereas the later-onset types are clinically heterogeneous. The only disease-modifying treatment currently available is hematopoietic stem cell transplantation, which is effective only when performed early in the course of the disease. Because most patients with KD are diagnosed too late for treatment, primary care physicians are faced with the challenge of caring for a child with severe neurologic impairment. This Review describes presenting symptoms, diagnosis, and disease manifestations of KD and provides basic guidelines for its management. Symptomatic treatment and supportive care that address the unique requirements of these patients can greatly improve the quality of life of patients and their families. © 2016 Wiley Periodicals, Inc.

Thickening of the cauda equina roots: a common finding in Krabbe disease.

OBJECTIVES: Evaluation of Krabbe disease burden and eligibility for hematopoietic stem cell transplantation are often based on neuroimaging findings using the modified Loes scoring system, which encompasses central but not peripheral nervous system changes. We show that quantitative evaluation of thickened cauda equina nerve roots may improve the evaluation of Krabbe disease and therapeutic guidance. METHODS: Lumbar spine MRI scans of patients obtained between March 2013 and September 2013 were retrospectively evaluated and compared to those of controls. Quantitative evaluation of cauda equina roots was performed on the axial plane obtained approximately 5 mm below the conus medullaris. The largest nerves in the right and left anterior quadrants of the spinal canal were acquired. RESULTS: Fifteen symptomatic patients with Krabbe disease (5-44 months old) and eleven age-matched controls were evaluated. The average areas (mm(2)) of anterior right and left nerves were 1.40 and 1.23, respectively, for patients and 0.61 and 0.60 for controls (differences: 0.79 and 0.63; p < 0.001). CONCLUSIONS: Cauda equina nerve root thickening is associated with Krabbe disease in both treated and untreated patients. Adding lumbar spine MRI to the current neurodiagnostic protocols, which fails to account for peripheral nerve abnormalities, will likely facilitate the diagnosis of Krabbe disease. KEY POINTS: • Neuroimaging is valuable for evaluating cauda equina nerve abnormality in Krabbe disease • MRI can be used to quantitatively evaluate cauda equina nerve thickening • Lumbar MRI could be useful for diagnosis and treatment monitoring of Krabbe disease.

Clinical outcomes of children with abnormal newborn screening results for Krabbe disease in New York State.

BACKGROUND: Early infantile Krabbe disease is rapidly fatal, but hematopoietic stem cell transplantation (HSCT) may improve outcomes if performed soon after birth. New York State began screening all newborns for Krabbe disease in 2006. METHODS: Infants with abnormal newborn screen results for Krabbe disease were referred to specialty-care centers. Newborns found to be at high risk for Krabbe disease underwent a neurodiagnostic battery to determine the need for emergent HSCT. RESULTS: Almost 2 million infants were screened. Five infants were diagnosed with early infantile Krabbe disease. Three died, two from HSCT-related complications and one from untreated disease. Two children who received HSCT have moderate to severe developmental delays. Forty-six currently asymptomatic children are considered to be at moderate or high risk for development of later-onset Krabbe disease. CONCLUSIONS: These results show significant HSCT-associated morbidity and mortality in early infantile Krabbe disease and raise questions about its efficacy when performed in newborns diagnosed through newborn screening. The unanticipated identification of "at risk" children introduces unique ethical and medicolegal issues. New York's experience raises questions about the risks, benefits, and practicality of screening newborns for Krabbe disease. It is imperative that objective assessments be made on an ongoing basis as additional states begin screening for this disorder.Genet Med 18 12, 1235-1243.

Newborn screening for Krabbe disease in New York State: the first eight years' experience.

PURPOSE: Krabbe disease (KD) results from galactocerebrosidase (GALC) deficiency. Infantile KD symptoms include irritability, progressive stiffness, developmental delay, and death. The only potential treatment is hematopoietic stem cell transplantation. New York State (NYS) implemented newborn screening for KD in 2006. METHODS: Dried blood spots from newborns were assayed for GALC enzyme activity using mass spectrometry, followed by molecular analysis for those with low activity (≤12% of the daily mean). Infants with low enzyme activity and one or more mutations were referred for follow-up diagnostic testing and neurological examination. RESULTS: Of >1.9 million screened, 620 infants were subjected to molecular analysis and 348 were referred for diagnostic testing. Five had enzyme activities and mutations consistent with infantile KD and manifested clinical/neurodiagnostic abnormalities. Four underwent transplantation, two are surviving with moderate to severe handicaps, and two died from transplant-related complications. The significance of many sequence variants identified is unknown. Forty-six asymptomatic infants were found to be at moderate to high risk for disease. CONCLUSIONS: The positive predictive value of KD screening in NYS is 1.4% (5/346) considering confirmed infantile cases. The incidence of infantile KD in NYS is approximately 1 in 394,000, but it may be higher for later-onset forms.

Liver transplantation for treatment of severe S-adenosylhomocysteine hydrolase deficiency.

A child with severe S-adenosylhomocysteine hydrolase (AHCY) deficiency (AHCY c.428A>G, p.Tyr143Cys; c.982T>G, p.Tyr328Asp) presented at 8 months of age with growth failure, microcephaly, global developmental delay, myopathy, hepatopathy, and factor VII deficiency. Plasma methionine, S-adenosylmethionine (AdoMet), and S-adenosylhomocysteine (AdoHcy) were markedly elevated and the molar concentration ratio of AdoMet:AdoHcy, believed to regulate a myriad of methyltransferase reactions, was 15% of the control mean. Dietary therapy failed to normalize biochemical markers or alter the AdoMet to AdoHcy molar concentration ratio. At 40 months of age, the proband received a liver segment from a healthy, unrelated living donor. Mean AdoHcy decreased 96% and the AdoMet:AdoHcy concentration ratio improved from 0.52±0.19 to 1.48±0.79 mol:mol (control 4.10±2.11 mol:mol). Blood methionine and AdoMet were normal and stable during 6 months of follow-up on an unrestricted diet. Average calculated tissue methyltransferase activity increased from 43±26% to 60±22%, accompanied by signs of increased transmethylation in vivo. Factor VII activity increased from 12% to 100%. During 6 postoperative months, head growth accelerated 4-fold and the patient made promising gains in gross motor, language, and social skills.