Transformation in pretreatment manifestations of Gaucher disease type 1 during two decades of alglucerase/imiglucerase enzyme replacement therapy in the International Collaborative Gaucher Group (ICGG) Gaucher Registry

This study tests the hypothesis that the prevalence of severe clinical manifestations in Gaucher disease type 1 (GD1) patients at the time of treatment initiation has changed since alglucerase/imiglucerase enzyme replacement therapy (ERT) was approved in the United States (US) in 1991. US alglucerase/imiglucerase‐treated GD1 patients from the International Collaborative Gaucher Group Gaucher Registry clinicaltrials.gov NCT00358943 were stratified by age at ERT initiation (<18, 18 to <50, ≥50 years), era of ERT initiation (1991‐1995, 1996‐2000, 2001‐2005, 2006‐2009), and splenectomy status pre‐ERT. Prevalence of splenectomy decreased dramatically across the eras among all age groups. Bone manifestations were more prevalent in splenectomized patients than non‐splenectomized patients in all age groups. Prevalence of bone manifestations differed across eras in certain age groups: non‐splenectomized patients had a lower prevalence of ischemic bone events (pediatric patients) and bone crisis (pediatric patients and adults 18 to <50 years) in later eras; splenectomized adult (18 to <50 years) patients had a lower prevalence of ischemic bone events and bone crisis in later eras. Over two decades after the introduction of ERT, the prevalence of splenectomy and associated skeletal complications has declined dramatically. Concomitantly, the interval between diagnosis and initiation of ERT has decreased, most strikingly in pediatric patients who have the most severe disease. Together, these findings suggest that since the introduction of alglucerase/imiglucerase ERT, optimal standard of care has become established in the US to prevent destructive complications of GD1.

Roscoe Owen Brady, MD: Remembrances of co-investigators and colleagues

To celebrate the research visions and accomplishments of the late Roscoe O. Brady (1923-2016), remembrance commentaries were requested from several of his postdoctoral research fellows and colleagues. These commentaries not only reflect on the accomplishments of Dr. Brady, but they also share some of the backstories and experiences working in the Brady laboratory. They provide insights and perspectives on Brady's research activities, and especially on his efforts to develop an effective treatment for patients with Type 1 Gaucher disease. These remembrances illuminate Brady's efforts to implement the latest scientific advances with an outstanding team of young co-investigators to develop and demonstrate the safety and effectiveness of the first enzyme replacement therapy for a lysosomal storage disease. Brady's pursuit and persistence in accomplishing his research objectives provide insights into this remarkably successful physician scientist who paved the way for the development of treatments for patients with other lysosomal storage diseases.

Long-term hematological, visceral, and growth outcomes in children with Gaucher disease type 3 treated with imiglucerase in the International Collaborative Gaucher Group Gaucher Registry

In Gaucher disease (GD), deficiency of lysosomal acid β-glucosidase results in a broad phenotypic spectrum that is classified into three types based on the absence (type 1 [GD1]) or presence and severity of primary central nervous system involvement (type 2 [GD2], the fulminant neuronopathic form, and type 3 [GD3], the milder chronic neuronopathic form). Enzyme replacement therapy (ERT) with imiglucerase ameliorates and prevents hematological and visceral manifestations in GD1, but data in GD3 are limited to small, single-center series. The effects of imiglucerase ERT on hematological, visceral and growth outcomes (note: ERT is not expected to directly impact neurologic outcomes) were evaluated during the first 5years of treatment in 253 children and adolescents (<18years of age) with GD3 enrolled in the International Collaborative Gaucher Group (ICGG) Gaucher Registry. The vast majority of GBA mutations in this diverse global population consisted of only 2 mutations: L444P (77%) and D409H (7%). At baseline, GD3 patients exhibited early onset of severe hematological and visceral disease and growth failure. During the first year of imiglucerase treatment, hemoglobin levels and platelet counts increased and liver and spleen volumes decreased, leading to marked decreases in the number of patients with moderate or severe anemia, thrombocytopenia, and hepatosplenomegaly. These improvements were maintained through Year 5. There was also acceleration in linear growth as evidenced by increasing height Z-scores. Despite devastating disease at baseline, the probability of surviving for at least 5years after starting imiglucerase was 92%. In this large, multinational cohort of pediatric GD3 patients, imiglucerase ERT provided a life-saving and life-prolonging benefit for patients with GD3, suggesting that, with proper treatment, many such severely affected patients can lead productive lives and contribute to society.

Skeletal Muscle in Healthy Subjects versus Those with GNE-Related Myopathy: Evaluation with Shear-Wave US--A Pilot Study

PURPOSE

To determine whether quantitative differences in shear-wave velocity (SWV) exist between normal skeletal muscle and those affected by GNE-related myopathy and to examine the effects of muscle anisotropy, depth, and axial preload on SWV in a healthy control group.

MATERIALS AND METHODS

This study was approved by the institutional review board and compliant with HIPAA. Informed consent was obtained from all study volunteers. Eight patients (four women and four men aged 30-50 years) with genetically and biopsy-proved GNE-related myopathy and five healthy volunteers (three women and two men aged 27-33 years) underwent SWV imaging with use of a 9-MHz linear transducer. The gastrocnemius muscles were evaluated in the patients with GNE-related myopathy, and the gastrocnemius, vastus lateralis, and rectus femoris muscles were evaluated in the healthy cohort. The effect of muscle anisotropy, axial preload, and sample volume depth were examined in the healthy cohort. The effect of anisotropy at a fixed depth and preload were examined in the patients with GNE-related myopathy.

RESULTS

Irrespective of the muscle, the mean SWV was significantly higher with the transverse orientation than with the longitudinal orientation (P < .001). In the healthy cohort, the mean SWV for superficial measurements was significantly lower than that for deep measurements (P < .02). The mean SWV with preload was significantly higher with compression (P < .001) for the rectus femoris only. The mean SWV was significantly lower in patients with GNE-related myopathy than in control subjects (P < .02).

CONCLUSION

SWV parametric imaging may provide a useful quantitative adjunct in the assessment of disease activity in patients with GNE-related myopathy. There is diminished SWV and muscle anisotropy in GNE-related myopathy.

GM1-gangliosidosis in American black bears: clinical, pathological, biochemical and molecular genetic characterization

G(M1)-gangliosidosis is a rare progressive neurodegenerative disorder due to an autosomal recessively inherited deficiency of lysosomal β-galactosidase. We have identified seven American black bears (Ursus americanus) found in the Northeast United States suffering from G(M1)-gangliosidosis. This report describes the clinical features, brain MRI, and morphologic, biochemical and molecular genetic findings in the affected bears. Brain lipids were compared with those in the brain of a G(M1)-mouse. The bears presented at ages 10-14 months in poor clinical condition, lethargic, tremulous and ataxic. They continued to decline and were humanely euthanized. The T(2)-weighted MR images of the brain of one bear disclosed white matter hyperintensity. Morphological studies of the brain from five of the bears revealed enlarged neurons with foamy cytoplasm containing granules. Axonal spheroids were present in white matter. Electron microscopic examination revealed lamellated membrane structures within neurons. Cytoplasmic vacuoles were found in the liver, kidneys and chondrocytes and foamy macrophages within the lungs. Acid β-galactosidase activity in cultured skin fibroblasts was only 1-2% of control values. In the brain, ganglioside-bound sialic acid was increased more than 2-fold with G(M1)-ganglioside predominating. G(A1) content was also increased whereas cerebrosides and sulfatides were markedly decreased. The distribution of gangliosides was similar to that in the G(M1)-mouse brain, but the loss of myelin lipids was greater in the brain of the affected bear than in the brain of the G(M1) mouse. Isolated full-length cDNA of the black bear GLB1 gene revealed 86% homology to its human counterpart in nucleotide sequence and 82% in amino acid sequence. GLB1 cDNA from liver tissue of an affected bear contained a homozygous recessive T(1042) to C transition inducing a Tyr348 to His mutation (Y348H) within a highly conserved region of the GLB1 gene. The coincidence of several black bears with G(M1)-gangliosidosis in the same geographic area suggests increased frequency of a founder mutation in this animal population.

Fabry disease - underestimated in the differential diagnosis of multiple sclerosis?

Objective

Fabry disease is a rare X-linked inherited lysosomal storage disorder affecting multiple organ systems. It includes central nervous system involvement via micro- and macroangiopathic cerebral changes. Due to its clinical symptoms and frequent MRI lesions, Fabry disease is commonly misdiagnosed as multiple sclerosis. We present an overview of cases from Fabry centres in Germany initially misdiagnosed with multiple sclerosis and report the clinical, MR-tomographical, and laboratory findings.

Methods

Eleven Fabry patients (one male, ten females) initially diagnosed with multiple sclerosis were identified from 187 patient records (5.9%) and analyzed for presenting symptoms, results of the initial diagnostic workup, and the clinical course of the disease.

Results

Four patients were identified as having a “possible” history of MS, and 7 patients as “definite” cases of multiple sclerosis (revised McDonald criteria). On average, Fabry disease was diagnosed 8.2 years (±9.8 years) after the MS diagnosis, and 12.8 years after onset of first symptoms (±10.3 years). All patients revealed white matter lesions on MRI. The lesion pattern and results of cerebrospinal fluid examination were inconsistent and non-specific. White matter lesion volumes ranged from 8.9 mL to 34.8 mL (mean 17.8 mL±11.4 mL). There was no association between extra-neurological manifestations or enzyme activity and lesion load.

Conclusion

There are several anamnestic and clinical hints indicating when Fabry disease should be considered a relevant differential diagnosis of multiple sclerosis, e.g. female patients with asymmetric, confluent white matter lesions on MRI, normal spinal MR imaging, ectatic vertebrobasilar arteries, proteinuria, or lack of intrathecally derived immunoglobulin synthesis.

Long-term follow-up after gene therapy for canavan disease

Canavan disease is a hereditary leukodystrophy caused by mutations in the aspartoacylase gene (ASPA), leading to loss of enzyme activity and increased concentrations of the substrate N-acetyl-aspartate (NAA) in the brain. Accumulation of NAA results in spongiform degeneration of white matter and severe impairment of psychomotor development. The goal of this prospective cohort study was to assess long-term safety and preliminary efficacy measures after gene therapy with an adeno-associated viral vector carrying the ASPA gene (AAV2-ASPA). Using noninvasive magnetic resonance imaging and standardized clinical rating scales, we observed Canavan disease in 28 patients, with a subset of 13 patients being treated with AAV2-ASPA. Each patient received 9 × 10(11) vector genomes via intraparenchymal delivery at six brain infusion sites. Safety data collected over a minimum 5-year follow-up period showed a lack of long-term adverse events related to the AAV2 vector. Posttreatment effects were analyzed using a generalized linear mixed model, which showed changes in predefined surrogate markers of disease progression and clinical assessment subscores. AAV2-ASPA gene therapy resulted in a decrease in elevated NAA in the brain and slowed progression of brain atrophy, with some improvement in seizure frequency and with stabilization of overall clinical status.

Juvenile-onset motor neuron disease caused by novel mutations in β-hexosaminidase

A 12 year-old female presented with a seven-year history of progressive muscle weakness, atrophy, tremor and fasciculations. Cognition was normal. Rectal biopsy revealed intracellular storage material and biochemical testing indicated low hexosaminidase activity consistent with juvenile-onset G(M2)-gangliosidosis. Genetic evaluation revealed compound heterozygosity with two novel mutations in the hexosaminidase β-subunit (c.512-3 C>A and c.1613+15_1613+18dup). Protein analysis was consistent with biochemical findings and indicated only a small portion of β-subunits were properly processed. These results provide additional insight into juvenile-onset G(M2)-gangliosidoses and further expand the number of β-hexosaminidase mutations associated with motor neuron disease.

The enigma of the E326K mutation in acid β-glucocerebrosidase

A large number of mutations, and several polymorphisms, have been characterized in the GBA gene, encoding the lysosomal enzyme glucocerebrosidase, the activity of which is impaired in Gaucher disease. In this communication we summarize published and new data concerning biochemical characterization of the E326K amino acid change (1093G>A in the GBA1 cDNA) in tissue culture and its association with Parkinson disease, suggesting it is a disease causing mutation and not merely a polymorphism in the GBA gene.

An open-label Phase I/II clinical trial of pyrimethamine for the treatment of patients affected with chronic GM2 gangliosidosis (Tay-Sachs or Sandhoff variants)

Late-onset GM2 gangliosidosis is an autosomal recessive, neurodegenerative, lysosomal storage disease, caused by deficiency of ß-hexosaminidase A (Hex A), resulting from mutations in the HEXA (Tay-Sachs variant) or the HEXB (Sandhoff variant) genes. The enzyme deficiency in many patients with juvenile or adult onset forms of the disease results from the production of an unstable protein, which becomes targeted for premature degradation by the quality control system of the smooth endoplasmic reticulum and is not transported to lysosomes. In vitro studies have shown that many mutations in either the α or β subunit of Hex A can be partially rescued, i.e. enhanced levels of both enzyme protein and activity in lysosomes, following the growth of patient cells in the presence of the drug, pyrimethamine. The objectives of the present clinical trial were to establish the tolerability and efficacy of the treatment of late-onset GM2 gangliosidosis patients with escalating doses of pyrimethamine, to a maximum of 100 mg per day, administered orally in a single daily dose, over a 16-week period . The primary objective, tolerability, was assessed by regular clinical examinations, along with a panel of hematologic and biochemical studies. Although clinical efficacy could not be assessed in this short trial, treatment efficacy was evaluated by repeated measurements of leukocyte Hex A activity, expressed relative to the activity of lysosomal ß-glucuronidase. A total of 11 patients were enrolled, 8 males and 3 females, aged 23 to 50 years. One subject failed the initial screen, another was omitted from analysis because of the large number of protocol violations, and a third was withdrawn very early as a result of adverse events which were not drug-related. For the remaining 8 subjects, up to a 4-fold enhancement of Hex A activity at doses of 50 mg per day or less was observed. Additionally marked individual variations in the pharmacokinetics of the drug among the patients were noted. However, the study also found that significant side effects were experienced by most patients at or above 75 mg pyrimethamine per day. We concluded that pyrimethamine treatment enhances leukocyte Hex A activity in patients with late-onset GM2 gangliosidosis at doses lower than those associated with unacceptable side effects. Further plans are underway to extend these trials and to develop methods to assess clinical efficacy.

Pathology of GM2 gangliosidosis in Jacob sheep

The G(M2) gangliosidoses are a group of lysosomal storage diseases caused by defects in the genes coding for the enzyme hexosaminidase or the G(M2) activator protein. Four Jacob sheep from the same farm were examined over a 3-year period for a progressive neurologic disease. Two lambs were 6-month-old intact males and 2 were 8-month-old females. Clinical findings included ataxia in all 4 limbs, proprioceptive deficits, and cortical blindness. At necropsy, the nervous system appeared grossly normal. Histologically, most neurons within the brain, spinal cord, and peripheral ganglia were enlarged, and the cytoplasm was distended by foamy to granular material that stained positively with Luxol fast blue and Sudan black B stains. Other neuropathologic findings included widespread astrocytosis, microgliosis, and scattered spheroids. Electron microscopy revealed membranous cytoplasmic bodies within the cytoplasm of neurons. Biochemical and molecular genetic studies confirmed the diagnosis of G(M2) gangliosidosis. This form of G(M2) gangliosidosis in Jacob sheep is very similar to human Tay-Sachs disease and is potentially a useful animal model.

Vitamin B12-responsive severe leukoencephalopathy and autonomic dysfunction in a patient with "normal" serum B12 levels

Leukoencephalopathy and autonomic dysfunction have been described in individuals with very low serum B(12) levels (<200 pg/ml), in addition to psychiatric changes, neuropathy, dementia and subacute combined degeneration. Elevated homocysteine and methylmalonic acid levels are considered more sensitive and specific for evaluating truly functional B(12) deficiency. A previously healthy 62-year-old woman developed depression and cognitive deficits with autonomic dysfunction that progressed over the course of 5 years. The patient had progressive, severe leukoencephalopathy on multiple MRI scans over 5 years. Serum B(12) levels ranged from 267 to 447 pg/ml. Homocysteine and methylmalonic acid levels were normal. Testing for antibody to intrinsic factor was positive, consistent with pernicious anaemia. After treatment with intramuscular B(12) injections (1000 μg daily for 1 week, weekly for 6 weeks, then monthly), she made a remarkable clinical recovery but remained amnesic for major events of the last 5 years. Repeat MRI showed partial resolution of white matter changes. Serum B(12), homocysteine and methylmalonic acid levels are unreliable predictors of B(12)-responsive neurologic disorders, and should be thoroughly investigated and presumptively treated in patients with unexplained leukoencephalopathy because even long-standing deficits may be reversible.

Tay-Sachs disease in Jacob sheep

Autopsy studies of four Jacob sheep dying within their first 6-8 months of a progressive neurodegenerative disorder suggested the presence of a neuronal storage disease. Lysosomal enzyme studies of brain and liver from an affected animal revealed diminished activity of hexosaminidase A (Hex A) measured with an artificial substrate specific for this component of β-hexosaminidase. Absence of Hex A activity was confirmed by cellulose acetate electrophoresis. Brain lipid analyses demonstrated the presence of increased concentrations of G(M2)-ganglioside and asialo-G(M2)-ganglioside. The hexa cDNA of Jacob sheep was cloned and sequenced revealing an identical number of nucleotides and exons as in human HexA and 86% homology in nucleotide sequence. A missense mutation was found in the hexa cDNA of the affected sheep caused by a single nucleotide change at the end of exon 11 resulting in skipping of exon 11. Transfection of normal sheep hexa cDNA into COS1 cells and human Hex A-deficient cells led to expression of Hex S but no increase in Hex A indicating absence of cross-species dimerization of sheep Hex α-subunit with human Hex β-subunits. Using restriction site analysis, the heterozygote frequency of this mutation in Jacob sheep was determined in three geographically separate flocks to average 14%. This large naturally occurring animal model of Tay-Sachs disease is the first to offer promise as a means for trials of gene therapy applicable to human infants.

Real Time Imaging of Biomarkers in the Parkinson's Brain Using Mini-Implantable Biosensors. II. Pharmaceutical Therapy with Bromocriptine

We used Neuromolecular Imaging (NMI) and trademarked BRODERICK PROBE^® mini-implantable biosensors, to selectively and separately detect neurotransmitters in vivo, on line, within seconds in the dorsal striatal brain of the Parkinson's Disease (PD) animal model. We directly compared our results derived from PD to the normal striatal brain of the non-Parkinson's Disease (non-PD) animal. This advanced biotechnology enabled the imaging of dopamine (DA), serotonin (5-HT), homovanillic acid (HVA) a metabolite of DA, L-tryptophan (L-TP) a precursor to 5-HT and peptides, dynorphin A 1-17 (Dyn A) and somatostatin (somatostatin releasing inhibitory factor) (SRIF). Each neurotransmitter and neurochemical was imaged at a signature electroactive oxidation/half-wave potential in dorsal striatum of the PD as compared with the non-PD animal. Both endogenous and bromocriptine-treated neurochemical profiles in PD and non-PD were imaged using the same experimental paradigm and detection sensitivities. Results showed that we have found significant neurotransmitter peptide biomarkers in the dorsal striatal brain of endogenous and bromocriptine-treated PD animals. The peptide biomarkers were not imaged in dorsal striatal brain of non-PD animals, either endogenously or bromocriptine-treated. These findings provide new pharmacotherapeutic strategies for PD patients. Thus, our findings are highly applicable to the clinical treatment of PD.

Variable expression of a novel PLP1 mutation in members of a family with Pelizaeus-Merzbacher disease

Pelizaeus-Merzbacher disease is a rare X-linked disorder caused by mutations of the proteolipid protein 1 gene that encodes a structural component of myelin. It is characterized by progressive psychomotor delay, nystagmus, spastic quadriplegia, and cerebellar ataxia. Variable clinical expression was seen in 5 members of a family bearing a novel missense mutation in proteolipid protein 1, c.619T>C. Symptomatic patients included a 6-year-old girl, her younger brother, and their maternal uncle, a 29-year-old college graduate initially diagnosed with cerebral palsy; their brain magnetic resonance imaging studies showed diffuse dysmyelination. The mother had a history of delayed walking, achieved independently by age 3; she and the maternal grandmother were asymptomatic on presentation. Review of clinical information and family history led to consideration of Pelizaeus-Merzbacher disease. Subsequent identification of the causal mutation enabled preimplantation genetic diagnosis and the birth of an unaffected child.

Newborn screening for Krabbe disease: the New York State model

Krabbe disease is a rare inherited neurologic disorder affecting the central and peripheral nervous systems. The disease has four phenotypes: early infantile, later onset, adolescent, and adult. The only known treatment is hematopoietic stem cell transplantation, which is, in the early infantile form of the disease, most beneficial if performed before onset of clinical symptoms. In August 2006, New York State began screening all newborns for Krabbe disease. A rapid and accurate technique for assessing galactocerebrosidase activity and performing DNA mutation analysis had been developed. Interpreting these results was limited, however, because neither enzyme activity nor genetic mutation reliably predicts phenotype. A series of initiatives were therefore developed by a multidisciplinary group of neurologists, geneticists, metabolic pediatricians, neurodevelopmental pediatricians, and transplant physicians (the Krabbe Consortium of New York State) to enhance the effectiveness of the newborn screening program. A standardized clinical evaluation protocol was designed based on the available literature, criteria for transplantation for the early infantile phenotype were formulated, a clinical database and registry was developed, and a study of developmental and functional outcomes was instituted. This multidisciplinary standardized approach to evaluating infants who have positive results on newborn screening may serve as a model for other states as they begin the process of screening for Krabbe disease and other lysosomal storage disorders.

Long-term efficacy and safety of laronidase in the treatment of mucopolysaccharidosis I

OBJECTIVE

Our goal was to evaluate the long-term safety and efficacy of recombinant human alpha-l-iduronidase (laronidase) in patients with mucopolysaccharidosis I.

PATIENTS AND METHODS

All 45 patients who completed a 26-week, double-blind, placebo-controlled trial of laronidase were enrolled in a 3.5-year open-label extension study. Mean patient age at baseline was 16 (range: 6-43) years. All patients had attenuated disease (84% Hurler-Scheie, 16% Scheie phenotypes). Clinical, biochemical, and health outcomes measures were evaluated through the extension phase. Changes are presented as the mean +/- SEM.

RESULTS

All 40 patients (89%) who completed the trial received at least 80% of scheduled infusions. As shown in earlier trials, urinary glycosaminoglycan levels decreased within the first 12 weeks and liver volume decreased within the first year. Percent predicted forced vital capacity remained stable, with a linear slope of -0.78 percentage points per year. The 6-minute walk distance increased 31.7 +/- 10.2 m in the first 2 years, with a final gain of 17.1 +/- 16.8 m. Improvements in the apnea/hypopnea index (decrease of 7.6 +/- 4.5 events per hour among the patients with significant baseline sleep apnea) and shoulder flexion (increase of 17.4 degrees +/- 3.6 degrees) were most rapid during the first 2 years. Improvements in the Child Health Assessment Questionnaire/Health Assessment Questionnaire disability index (decrease of 0.31 +/- 0.11, signifying a clinically meaningful improvement in activities of daily living) were gradual and sustained over the treatment period. Laronidase infusions were generally well tolerated except in 1 patient who experienced an anaphylactic reaction. Infusion-associated reactions, which occurred in 53% of the patients, were mostly mild, easily managed, and decreased markedly after 6 months. One patient died as a result of an upper respiratory infection unrelated to treatment. Antibodies to laronidase developed in 93% of the patients; 29% of the patients were seronegative at their last assessment.

CONCLUSIONS

This trial demonstrates the long-term clinical benefit and safety of laronidase in attenuated patients with mucopolysaccharidosis I and highlights the magnitude and chronology of treatment effects. Prompt diagnosis and early treatment will maximize treatment outcomes.

Late-onset Tay-Sachs disease: the spectrum of peripheral neuropathy in 30 affected patients

Late-onset Tay-Sachs (LOTS) disease is a chronic, progressive, lysosomal storage disorder caused by a partial deficiency of beta-hexosaminidase A (HEXA) activity. Deficient levels of HEXA result in the intracellular accumulation of GM2-ganglioside, resulting in toxicity to nerve cells. Clinical manifestations primarily involve the central nervous system (CNS) and lower motor neurons, and include ataxia, weakness, spasticity, dysarthria, dysphagia, dystonia, seizures, psychosis, mania, depression, and cognitive decline. The prevalence of peripheral nervous system (PNS) involvement in LOTS has not been well documented, but it has traditionally been thought to be very low. We examined a cohort of 30 patients with LOTS who underwent clinical and electrophysiologic examination, and found evidence of a predominantly axon loss polyneuropathy affecting distal nerve segments in the lower and upper extremities in eight patients (27%).

Spontaneous appearance of Tay-Sachs disease in an animal model

Tay-Sachs disease (TSD) is a progressive neurodegenerative disorder due to an autosomal recessively inherited deficiency of beta-hexosaminidase A (Hex A). Deficiency of Hex A in TSD is caused by a defect of the alpha-subunit resulting from mutations of the HEXA gene. To date, there is no effective treatment for TSD. Animal models of genetic diseases, similar to those known to exist in humans, are valuable and essential research tools for the study of potentially effective therapies. However, there is no ideal animal model of TSD available for use in therapeutic trials. In the present study, we report an animal model (American flamingo; Phoenicopterus ruber) of TSD with Hex A deficiency occurring spontaneously in nature, with accumulation of G(M2)-ganglioside, deficiency of Hex A enzymatic activity, and a homozygous P469L mutation in exon 12 of the hexa gene. In addition, we have isolated the full-length cDNA sequence of the flamingo, which consists of 1581 nucleotides encoding a protein of 527 amino acids. Its coding sequence indicates approximately 71% identity at the nucleotide level and about 72.5% identity at the amino acid level with the encoding region of the human HEXA gene. This animal model, with many of the same features as TSD in humans, could represent a valuable resource for investigating therapy of TSD.

Very long chain acyl-CoA dehydrogenase deficiency in a pair of mildly affected monozygotic twin sister in their late fifties

Very long-chain acyl-CoA dehydrogenase (VLCAD) catalyses the initial step of mitochondrial beta-oxidation of long-chain fatty acids with a chain length of 14 to 20 carbons. Deficiency of VLCAD activity has been associated with a range of phenotypes, including a severe lethal form presenting in the infantile period and a milder variant with onset in childhood. Varying rates of residual enzyme activity partly explain the heterogeneity in presentations. Here we report the course of disease in a pair of monozygotic twin sisters who were diagnosed in their late forties during an evaluation for rhabdomyolysis and fatigue. Interestingly, the patients' complaints were most severe during puberty and declined significantly after the menopause. The basis for this observation is uncertain, but may be related to hormonally-mediated changes in lipid metabolism that may occur at these times. As metabolic decompensation can be associated with significant morbidity, timely diagnosis of VLCAD deficiency is important. The introduction of appropriate dietary measures (i.e. avoidance of fasting, long-chain fat restriction and supplementation with medium-chain triglycerides) greatly reduces the likelihood of complications.

Rapid detection of three large novel deletions of the aspartoacylase gene in non-Jewish patients with Canavan disease

Canavan disease (CD), an autosomal recessive neurodegenerative disorder, is caused by mutations in the aspartoacylase (ASPA) gene. In the present study, the ASPA gene was analyzed in 24 non-Jewish patients with CD from 23 unrelated families. Within this cohort, we found three large novel deletions of approximate 92, 56, and 12.13 kb in length, using both self-ligation of restriction endonuclease-digested DNA fragments with long-distance inverse PCR and multiplex dosage quantitative PCR analysis of genomic DNA. The 92 kb large deletion results in complete absence of the ASPA gene in one homozygous and one compound heterozygous patient, respectively. The 56 kb large deletion causes absence of the majority of the ASPA gene except for exon 1 alone in a compound heterozygous patient. The 12.13 kb deletion involves deletion of the ASPA gene from intron 3 to intron 5 including exons 4 and 5 (I3 to E4E5I5) in a compound heterozygous patient. Patients with the three large deletions clinically manifested severe symptoms at birth, including seizures. Our study showed that the combined use of long-distance inverse PCR and multiplex dosage quantitative PCR analysis of genomic DNA is a helpful and rapid technique to search for large deletions, particularly for detection of large deletions in compound heterozygous patients.

Leukodystrophies: clinical and genetic aspects

The leukodystrophies comprise an ever-expanding group of rare central nervous system disorders with defined clinical, pathological, and genetic characteristics. The broader term, leukoencephalopathy, is applied to all brain white matter diseases, whether their molecular cause is known. Magnetic resonance imaging has helped to elucidate new forms of leukodystrophy as well as to permit longitudinal studies of disease progression. The white matter abnormality may appear similar in different forms of leukodystrophy so that in most cases, further studies such as magnetic resonance spectroscopy, tissue biopsies, enzyme studies, and molecular DNA analyses are needed to pinpoint the specific diagnosis. The primary inherited leukoencephalopathies include dysmyelinating, hypomyelinative, and vacuolating forms. Metabolic and vascular causes account for most of the secondary forms, but other inherited syndromes are recognized that have their onset in childhood or adult life and are characterized by distinctive clinical and neuropathologic features. This review discusses some of the mechanisms that have been proposed to explain deficiencies of myelin and the molecular genetic bases underlying these disorders.

An open-label, noncomparative study of miglustat in type I Gaucher disease: efficacy and tolerability over 24 months of treatment

BACKGROUND

The substrate synthesis inhibitor miglustat (N-butyldeoxynojirimycin) is the first oral agent to receive regulatory approval for the treatment of type I Gaucher disease (GD).

OBJECTIVES

The aims of this study were to further assess previous observations of the effects of miglustat in adult patients with mild to moderate type I GD and to evaluate the tolerability and safety profile of this drug.

METHODS

This was a noncomparative, open-label study in adult patients with type I GD (confirmed by genotyping and glucocerebrosidase assay) who were unwilling or unable to receive enzyme replacement therapy (ERT) or who had discontinued ERT for at least 3 months. Patients received miglustat 100 mg TID for 12 months, with the option of continuing treatment for a further 12 months. The primary end point was the percentage change in liver volume. Secondary end points included the percentage change in spleen volume and changes in hematologic parameters (hemoglobin, platelets), chitotriosidase activity (a surrogate marker of disease burden), and bone assessments (dual-energy X-ray absorptiometry, magnetic resonance imaging, and radiography). Clinical safety was monitored, including assessment of neurologic status at baseline and throughout the study using a comprehensive battery of standardized neurologic tests (eg, Purdue Pegboard Test, Mini-Mental State Examination, nerve conduction studies) and neuropsychological tests.

RESULTS

Of the 10 patients (7 men, 3 women) who received at least 1 dose of miglustat, 7 completed 24 months of treatment. Patients were aged between 32 and 62 years (mean, 46.3 years) and weighed between 55 and 88 kg (mean, 72.4 kg). All patients had at least 1 manifestation of GD, including 10 with splenomegaly (mean size, 8.1 times normal; range, 3.9-15.9 times normal), 9 with thrombocytopenia, and 8 with hepatomegaly (mean size, 1.5 times normal; range, 1.0-2.0 times normal). At baseline, hemoglobin concentrations ranged from 11.5 to 15.1 g/dL (mean, 13.2 g/dL), platelet counts from 55 to 161 x 10(9)/L (mean, 83.8 x 10(9)/L), and chitotriosidase activity from 526 to 29636 nmol/mL . h (mean, 8143.7 nmol/mL . h). In the 8 patients comprising the efficacy set, significant mean percentage changes from baseline in liver volume were seen at 6 months (-8.4%; P = 0.036; 95% CI, -16.1 to -0.7) and 18 months (-15.1%; P = 0.022; 95% CI, -27.1 to -3.0). Although not statistically significant, the 95% CIs for the percentage changes in liver volume at 12 months (-9.4%; 95% CI, -19.5 to 0.6) and 24 months (-5.6%; 95% CI, -12.1 to 1.0) were similar to those at 6 and 18 months, supporting a consistent clinical effect. Significant mean percentage reductions in spleen volume were observed at 6 months (-19.0%; P = 0.006; 95% CI, -30.4 to -7.6) and 18 months (-24.3%; P = 0.001; 95% CI, -33.6 to -15.1). Mean hemoglobin concentrations, which were normal at baseline, remained stable over the course of the study. There were no significant changes in bone status. There was a significant mean increase in absolute platelet count at 12 months (by 13.9 x 10(9)/L; P = 0.030; 95% CI, 1.8 to 26.0); at 24 months, the mean percentage increase from baseline (23.0%) was not statistically significant. The mean percentage reduction from baseline in chitotriosidase activity at 24 months was 25.3%. Treatment was well tolerated, and the incidence of most adverse events decreased with time. Gastrointestinal and central nervous system adverse events reported during 3-month periods at the beginning (0-3 months) and end (>21-24 months) of the study were flatulence (10 and 2 patients, respectively), diarrhea (9 and 0), abdominal pain (7 and 1), tremor (4 and 1), paresthesia (3 and 0), headache (2 and 3), and abdominal distention (2 and 0). No evidence of clinically significant adverse effects on neurologic or neuropsychological function was found during the study.

CONCLUSIONS

In this small study in symptomatic adult patients with type I GD, miglustat treatment resulted in a significant decrease in liver and spleen volume at 6 and 18 months, with clinical improvement noted over 24 months. Bone involvement and platelet and hemoglobin values remained stable, with no significant changes noted during the observation period. The effects of treatment were consistent with those of earlier studies of miglustat in type I GD.

Mild-onset presentation of Canavan's disease associated with novel G212A point mutation in aspartoacylase gene

We describe two sisters with a mild-onset variant of Canavan's disease who presented at age 50 and 19 months with developmental delay but without macrocephaly, hypotonia, spasticity, or seizures. Remarkably, both patients had age-appropriate head control, gross motor development, and muscle tone. There were very mild deficits in fine motor skills, coordination, and gait. Both sisters had a history of strabismus, but otherwise vision was normal. The older child showed evidence of mild cognitive and social impairment, whereas language and behavior were normal for age in the infant. Both patients were found to be compound heterozygotes for C914A (A305E) and G212A (R71H) mutations in ASPA. Like all other known ASPA mutations, this previously unknown G212A mutation appears to have low absolute enzyme activity. Nevertheless, it is associated in these patients with an extremely benign phenotype that is highly atypical of Canavan's disease. Biochemical and clinical data were evaluated using a generalized linear mixed model generated from 25 other subjects with Canavan's disease. There were statistically significant differences in brain chemistry and clinical evaluations, supporting a distinct variant of Canavan's disease. Future studies of ASPA enzyme structure and gene regulation in these subjects could lead to a better understanding of Canavan's pathophysiology and improvements in ASPA gene therapy.

MR imaging and proton spectroscopy of neuronal injury in late-onset GM2 gangliosidosis

BACKGROUND AND PURPOSE

Despite the ubiquity of G(M2) gangliosides accumulation in patients with late-onset G(M2) gangliosidosis (G(M2)G), the only clinical MR imaging-apparent brain abnormality is profound cerebellar atrophy. The goal of this study was to detect the presence and assess the extent of neuroaxonal injury in the normal-appearing gray and white matter (NAGM and NAWM) of these patients.

METHODS

During a single imaging session, 9 patients with late-onset G(M2)G and 8 age-matched normal volunteers underwent the following protocol: (1) T1- and T2-weighted and fluid-attenuated inversion recovery MR images, as well as (2) multivoxel proton MR spectroscopy (1H-MR spectroscopy) to quantify the distribution of the n-acetylaspartate (NAA), creatine (Cr), and choline (Cho), were obtained.

RESULTS

The patients' NAA levels in the thalamus (6.5 +/- 1.9 mmol/L) and NAWM (5.8 +/- 2.1 mmol/L) were approximately 40% lower than the controls' (P = .003 and P = .005), whereas the Cr and Cho reductions ( approximately 30% and approximately 26%) did not reach significance (P values of .06-.1). All cerebellar metabolites, especially NAA and Cr, were much (30%-90%) lower in the patients, which reflects the atrophy.

CONCLUSION

In late-onset G(M2)G, NAA decreases are detectable in NAGM and NAWM even absent morphologic (MR imaging) abnormalities. Because the accumulation of G(M2) gangliosides can be reduced pharmacologically, 1H-MR spectroscopy might be a sensitive and specific for detecting and quantifying neuroaxonal injury and monitoring response to emerging treatments.

Late-onset Tay-Sachs disease: phenotypic characterization and genotypic correlations in 21 affected patients

PURPOSE

The purpose of this study was to describe the phenotype (and corresponding genotype) of adult patients with late-onset Tay-Sachs disease, a clinical variant of the GM2-gangliosidoses.

METHODS

A comprehensive physical examination, including neurological assessments, was performed to establish the current disease pattern and severity. In addition, the patients' past medical histories were reviewed. The patients' alpha-subunit mutations (beta-Hexosaminidase A genotype) were determined and correlated with their corresponding clinical findings and disease course.

RESULTS

Twenty-one patients (current mean age: 27.0 years; range: 14-47 years) were identified. The pedigree revealed a relative with the "classic" infantile or late-onset form of Tay-Sachs disease in four (out of 18) unrelated families. The patients were predominantly male (15/21 individuals) and of Ashkenazi Jewish ancestry (15/18 families). Mean age at onset was 18.1 years; balance problems and difficulty climbing stairs were the most frequent presenting complaints. In several cases, the diagnosis was delayed (mean age at diagnosis: 27.0 years). Analysis of the beta-hex A gene revealed the G269S mutation as the most common disease allele; found in homozygosity (N = 1) or heterozygosity (N = 18; including 2 sib pairs). Disease onset (age 36 years) was delayed and progression relatively slower in the homozygous G269S patient. Two siblings (ages 28 and 31 years), of non-Jewish ancestry, were compound heterozygotes (TATC1278/W474C); their clinical course is dominated by psychiatric problems. Brain imaging studies revealed marked cerebellar atrophy in all patients (N = 18) tested, regardless of disease stage.

CONCLUSIONS

Late-onset Tay-Sachs disease is an infrequent disorder and the diagnosis is often missed or delayed (by approximately 8 years). Early on, the majority of patients develop signs of either cerebellar or anterior motor neuron involvement. Affected individuals may also develop psychotic episodes. In most cases, the later-onset of expression results from the presence of at least one allele (usually the G269S mutation), associated with residual enzyme (beta-hexosaminidase A) activity. A positive family history is a valuable clue, enabling early diagnosis. Nonspecific cerebellar atrophy on brain imaging is another important finding. This entity should be considered among patients presenting with speech, gait, and balance problems, and those with psychiatric disorders even when focal neurologic deficits may be initially absent. Accurate diagnosis will permit appropriate genetic counseling regarding disease prognosis and reproductive risks.

Globoid cell leukodystrophy (Krabbe disease): normal umbilical cord blood galactocerebrosidase activity and polymorphic mutations

Globoid cell leukodystrophy is an inherited metabolic disorder of the central nervous system caused by deficiency of the lysosomal enzyme galactocerebrosidase. Haematopoietic stem cell transplantation is the only available effective treatment. The engraftment from normal donors provides competent cells able to correct the metabolic defect. Umbilical cord blood cells have proved to significantly decrease complications and improve engraftment rate compared to adult marrow cells in haematopoietic stem cell transplantation. Umbilical cord blood cells must be of sufficient activity to provide central nervous system recovery after engraftment is obtained. Galactocerebrosidase activity is known to be affected by two polymorphic alleles found at nucleotides 502 and 1637 of the cDNA for this gene. This enzyme activity and the polymorphic alleles noted above were analysed in 83 random samples of umbilical cord blood. The activity, assayed with the fluorogenic substrate 6-hexadecanoylamino-4-methylumbelliferyl-beta-galactopyranoside, in those with neither polymorphic allele was 4.6 +/- 1.7 units (nmol/h per mg protein). This optimal choice of cord blood was found in only 24% of specimens. Homozygotes for 1637T > C with activity of only 1.5 +/- 0.4 units represented 16% of the samples. Those heterozygous for 1637T > C with slightly better activity (2.3 +/- 0.7 units) represented 52% of the samples. Choice of umbilical cord blood for haematopoietic stem cell transplantation, therefore, requires consideration not only of cell quantity and HLA compatibility but also selection for normal alleles to obtain maximal enzymatic activity for central nervous system correction.

Neuropsychological assessment of patients with late onset GM2 gangliosidosis

OBJECTIVE

To characterize cognitive status in a sample of individuals with late-onset GM2 gangliosidosis (commonly referred to as late-onset Tay-Sachs disease).

METHODS

Seventeen subjects (13 men, 4 women) diagnosed with GM2 gangliosidosis were evaluated. Subjects ranged in age from 18 to 56 years and were in various stages of disease progression. Subjects underwent comprehensive neuropsychological assessment. Impairment was defined as performance more than 1.6 SD below the normative mean.

RESULTS

Group mean performance was within the denoted normal range on all measures except on a task assessing visual sequencing and set shifting. Approximately one-half of the sample scored in the impaired range on measures of processing speed, visual sequencing, and set shifting. One-third of the sample also scored in the impaired range on measures of delayed verbal recall. Impairment tended to be restricted to a subset of the sample, as 5 of the 14 subjects able to undergo formal testing accounted for 70% of the total number of impaired scores. If the three subjects unable to participate in formal testing are also considered impaired, 47% of the current sample exhibited significant cognitive impairment in at least one cognitive domain.

CONCLUSION

In late-onset GM2 gangliosidosis, there is a risk of impairment in executive functioning and memory as well as cerebellar dysfunction. Dementia was not present in any subjects in the current sample.

Gaucher disease type 1: Revised recommendations on evaluations and monitoring for adult patients

For patients with type 1 Gaucher disease, challenges to patient care posed by clinical heterogeneity, variable progression rates, and potential permanent disability that can result from untreated or suboptimally treated hematologic, skeletal, and visceral organ involvement dictate a need for comprehensive, serial monitoring. An updated consensus on minimum recommendations for effective monitoring of all adult patients with type 1 Gaucher disease has been developed by the International Collaborative Gaucher Group (ICGG) Registry coordinators. These recommendations provide a schedule for comprehensive and reproducible evaluation and monitoring of all clinically relevant aspects of this disease. The initial assessment should include confirmation of deficiency of beta-glucocerebrosidase, genotyping, and a complete family medical history. Other assessments to be performed initially and at regular intervals include a complete physical examination, patient-reported quality of life using the SF-36 survey, and assessment of hematologic (hemoglobin and platelet count), visceral, and skeletal involvement, and biomarkers. Specific radiologic imaging techniques are recommended for evaluating visceral and skeletal pathology. All patients should undergo comprehensive regular assessment, the frequency of which depends on treatment status and whether therapeutic goals have been achieved. Additionally, reassessment should be performed whenever enzyme therapy dose is altered, or in case of significant clinical complication.

Enzyme replacement therapy for mucopolysaccharidosis I: a randomized, double-blinded, placebo-controlled, multinational study of recombinant human alpha-L-iduronidase (laronidase)

OBJECTIVE

To confirm the efficacy and safety of recombinant human alpha-L-iduronidase (laronidase) in patients with mucopolysaccharidosis I (MPS I).

STUDY DESIGN

This was a randomized, double-blinded, multinational study of 45 patients with MPS I administered 100 U/kg (0.58 mg/kg) laronidase, or placebo intravenously weekly for 26 weeks. The coprimary efficacy end points compared the median change from baseline to week 26 between groups in percentage of predicted normal forced vital capacity (FVC) and in 6-minute walk test (6MWT) distance through the use of the Wilcoxon rank sum test.

RESULTS

The laronidase (n=22) and placebo (n=23) groups had similar baseline characteristics. After 26 weeks, patients receiving laronidase compared with placebo showed mean improvements of 5.6 percentage points in percent of predicted normal FVC (median, 3.0; P=.009) and 38.1 meters in 6MWT distance (median, 38.5; P=.066; P=.039, analysis of covariance). Laronidase also significantly reduced hepatomegaly and urinary glycosaminoglycans, and, in more severely affected patients, improved sleep apnea/hypopnea and shoulder flexion. Laronidase was well-tolerated. Nearly all patients receiving enzyme had development of IgG antibodies, without apparent clinical effects.

CONCLUSIONS

In patients with MPS I, laronidase significantly improves respiratory function and physical capacity, reduces glycosaminoglycan storage, and has a favorable safety profile.

Reduced cerebral blood flow velocity and impaired cerebral autoregulation in patients with Fabry disease

In Fabry disease, there is glycosphingolipid storage in vascular endothelial and smooth muscle cells and neurons of the autonomic nervous system. Vascular or autonomic dysfunction is likely to compromise cerebral blood flow velocities and cerebral autoregulation. This study was performed to evaluate cerebral blood flow velocities and cerebral autoregulation in Fabry patients. In 22 Fabry patients and 24 controls, we monitored resting respiratory frequency, electrocardiographic RR-intervals, blood pressure, and cerebral blood flow velocities (CBFV) in the middle cerebral artery using transcranial Doppler sonography. We assessed the Resistance Index, Pulsatility Index, Cerebrovascular Resistance, and spectral powers of oscillations in RR-intervals, mean blood pressure and mean CBFV in the high (0.15-0.5 Hz) and sympathetically mediated low frequency (0.04-0.15 Hz) ranges using autoregressive analysis. Cerebral autoregulation was determined from the transfer function gain between the low frequency oscillations in mean blood pressure and mean CBFV. Mean CBFV (P < 0.05) and the powers of mean blood pressure (P < 0.01) and mean CBFV oscillations (P < 0.05) in the low frequency range were lower,while RR-intervals, Resistance Index (P < 0.01), Pulsatility Index, Cerebrovascular Resistance (P < 0.05), and the transfer function gain between low frequency oscillations in mean blood pressure and mean CBFV (P < 0.01) were higher in patients than in controls. Mean blood pressure, respiratory frequency and spectral powers of RR-intervals did not differ between the two groups (P > 0.05). The decrease of CBFV might result from downstream stenoses of resistance vessels and dilatation of the insonated segment of the middle cerebral artery due to reduced sympathetic tone and vessel wall pathology with decreased elasticity. The augmented gain between blood pressure and CBFV oscillations indicates inability to dampen blood pressure fluctuations by cerebral autoregulation. Both, reduced CBFV and impaired cerebral autoregulation, are likely to be involved in the increased risk of stroke in patients with Fabry disease.

A neurological symptom survey of patients with type I Gaucher disease

Gaucher disease is an inborn error of glycosphingolipid metabolism resulting from deficiency of the lysosomal enzyme glucocerebrosidase. The majority of the patients (with type I disease) do not have primary central nervous system involvement. However, several studies have noted that secondary neurological complications may develop as a consequence of nerve root or spinal cord compression following vertebral body collapse or, for those with coagulation disorders, bleeding within confined compartments. An epidemiological survey was conducted to ascertain the incidence of neurological symptoms in patients with Gaucher disease type I (GD I). The survey included a review of the patients' medical history, an estimate of Gaucher disease severity according to a modified Symptom Severity Index (SSI), and completion of a questionnaire regarding their neurological status and Quality of Life (QoL) according to the SF-36 Health Survey. Seventy-three per cent of respondents were found to have experienced at least one neurological complaint in the preceding 3 months. Adult patients with Gaucher disease often have other medical problems unrelated to their primary diagnosis. Thus, the high incidence of neurological complaints in these patients may be attributable to concurrent medical problems and/or side-effects from concomitant medications. These issues may influence patients' assessment of their disease severity and/or response to treatment.

Therapeutic effects of astrocytes expressing both tyrosine hydroxylase and brain-derived neurotrophic factor on a rat model of Parkinson's disease

Tyrosine hydroxylase (TH) and brain-derived neurotrophic factor (BDNF), expressed in normal astrocytes, were used in combination for the treatment of Parkinson's disease (PD) symptoms in a rat model. Normal neonatal rat astrocytes were co-transfected with a vector expressing BDNF (AAVBDNF) and a retroviral vector expressing TH (termed TH-BDNF-DA(+) cells), and then implanted into the striatum of PD rats induced by 6-hydroxydopamine. TH-BDNF-DA(+) cells compensated for a severe insufficiency of endogenous dopaminergic neurons in the PD rats, resulting in a significant improvement of PD symptoms. The decrease in the rotational rate of PD rats implanted with TH-BDNF-DA(+) cells was more marked than that in PD rats implanted with normal astrocytes expressing either TH or BDNF alone (termed TH(+) and BDNF(+) cells, P<0.01 and 0.001, respectively), and suggested a synergistic effect between TH and BDNF. In contrast, the rotational rate was not altered from the baseline in PD rats without treatment or implanted with parental rat astrocytes alone (P>0.05). BDNF protected the dopaminergic neurons from apoptosis induced by 6-hydroxydopamine, and significantly increased the long-term survival of TH-positive cells in the striatum. Our data indicate that the combined use of TH and BDNF has a synergistic therapeutic effect, and is more efficient for the treatment of PD than a single gene therapy using either TH or BDNF alone.

Identification and characterization of novel mutations of the aspartoacylase gene in non-Jewish patients with Canavan disease

Canavan disease, an inherited leukodystrophy, is caused by mutations in the aspartoacylase (ASPA) gene. It is most common among children of Ashkenazi Jewish descent but has been diagnosed in many diverse ethnic groups. Two mutations comprise the majority of mutant alleles in Jewish patients, while mutations in the ASPA gene among non-Jewish patients are different and more diverse. In the present study, the ASPA gene was analysed in 22 unrelated non-Jewish patients with Canavan disease, and 24 different mutations were found. Of these, 14 are novel, including five missense mutations (E24G, D68A, D249V, C152W, H244R), two nonsense mutations (Q184X, E214X), three deletions (923delT, 33del13, 244delA), one insertion mutation (698insC), two sequence variations in one allele ([10T>G; 11insG]), an elimination of the stop codon (941A>G, TAG-->TGG, X314W), and one splice acceptor site mutation (IVS1 - 2A>T). The E24G mutation resulted in substitution of an invariable amino acid residue (Glu) in the first esterase catalytic domain consensus sequence. The IVS1 - 2A>T mutation caused the retention of 40 nucleotides of intron 1 upstream of exon 2. The results of transient expression of the mutant ASPA cDNA containing these mutations in COS-7 cells and assays for ASPA activity of patient fibroblasts indicated that these mutations were responsible for the enzyme deficiency. In addition, patients with the novel D249V mutation manifested clinically at birth and died early. Also, patients with certain other novel mutations, including C152W, E214X, X314W, and frame shift mutations in both alleles, developed clinical manifestations at an earlier age than in classical Canavan disease.

Effectiveness of enzyme replacement therapy in 1028 patients with type 1 Gaucher disease after 2 to 5 years of treatment: a report from the Gaucher Registry

PURPOSE

Gaucher disease is the first lysosomal storage disorder to be treated with macrophage-targeted enzyme replacement therapy. Previous studies in relatively small numbers of patients demonstrated short-term efficacy of this treatment. This study describes the effects of 2 to 5 years of treatment on specific manifestations of type 1 Gaucher disease.

SUBJECTS AND METHODS

Physicians reported data from 1028 patients to the Gaucher Registry. Assessment of response included serial measurements of hemoglobin concentration, platelet count, liver and spleen volumes, and the occurrence of bone pain and bone crises.

RESULTS

Among anemic patients, hemoglobin concentration increased to normal or near normal within 6 to 12 months, with a sustained response through 5 years. In thrombocytopenic patients with intact spleens, the most rapid response occurred during the first 2 years, with slower improvement thereafter. The likelihood of achieving a normal platelet count decreased with increasing severity of baseline thrombocytopenia. In patients who had undergone splenectomy, platelet counts returned to normal within 6 to 12 months. Hepatomegaly decreased by 30% to 40% during follow-up; splenomegaly decreased 50% to 60%, but rarely to volumes below five times normal size. In patients with pretreatment bone pain or bone crises, 52% (67/128) were pain free after 2 years and 94% (48/51) reported no additional crises.

CONCLUSION

Enzyme replacement therapy prevents progressive manifestations of Gaucher disease, and ameliorates Gaucher disease-associated anemia, thrombocytopenia, organomegaly, bone pain, and bone crises.

Rapid detection of the two common mutations in Ashkenazi Jewish patients with mucolipidosis type IV

Among Ashkenazi Jewish individuals with mucolipidosis IV (ML IV), two mutations in the ML IV gene, IVS3-1A --> G and delEX1-EX7, account for more than 95% of disease alleles. The reported method of genotyping for the delEX1-EX7 mutation involves a cumbersome multistep procedure. In the present study, a new simplified one-step procedure is described that detects this mutation in both patients and carriers. An improved procedure is also described for detection of the IVS3-1A --> G mutation. Using these improved procedures, we have characterized the ML IV mutant alleles in 27 patients and 95 of their relatives from 22 families, and in 123 unrelated and unaffected Ashkenazi Jewish controls. Of the 27 ML IV patients, 16 patients (59.3%) were found to be homozygous for the IVS3-1A --> G mutation and 1 patient (3.7%) homozygous for the delEX1-EX7 mutation. Additionally, 9 patients (33.3%) were compound heterozygotes for IVS3-1A --> G/delEX1-EX7. Among the 123 Ashkenazi Jewish controls, two individuals were identified as heteroallelic with one IVS3-1A --> G mutation (carrier frequency: approximately 1 in 61); none showed the delEX1-EX7 mutation. The modifications described here provide a more facile means of genotyping patients and carriers and expand the possibilities for screening at-risk populations.