PubMed Health⌕ Search

Biomedical subjects

Ellen Sidransky

Publications and source records attributed to Ellen Sidransky.

At least 19 recordsLinked to original sources
PubMed2006

Therapy for Gaucher disease: don't stop thinking about tomorrow.

While enzyme replacement therapy for Gaucher disease has been widely used and appears to be an efficacious and safe treatment, this success should not be a reason for complacency. Other treatment strategies currently under consideration for patients with Gaucher disease include gene therapy, substrate reduction therapy and chaperone therapy. Furthermore, improvements in enzyme therapy could also have a significant clinical impact. Individuals with Gaucher disease and other lysosomal disorders will greatly benefit from continual refinement and optimization of the current therapy, as well as from the development of new treatment modalities that offer improvements in efficacy, cost, safety and availability.

Gaucher Disease↗
PubMed2006

Glucocerebrosidase mutations are not found in association with LRRK2 G2019S in subjects with parkinsonism.

Alteration G2019S in the leucine-rich repeat kinase 2 gene (LRRK2) has been identified in several populations of patients with parkinsonism, including Ashkenazi Jewish subjects with Parkinson disease. Mutations in glucocerebrosidase (GBA), the enzyme deficient in Gaucher disease, are also identified at an increased frequency among Parkinson probands, including those of Ashkenazi Jewish ancestry. A Taqman Assay-by-Design SNP genotyping strategy was utilized to establish whether G2019S was found in association with GBA mutations. Among 37 subjects with parkinsonism who were heterozygous for a GBA mutation, none carried G2019S. Furthermore, G2019S was not found in 18 patients with Gaucher disease who developed parkinsonian manifestations and 11 other Gaucher probands with parkinsonism in a first degree relative. Among 45 patients with Gaucher disease without a history of parkinsonism, one G2019S carrier was found. These findings suggest that GBA and LRRK2 mutations are discrete risk factors for parkinsonism in both Ashkenazi Jewish and non-Jewish subjects.

Amino Acid Substitution↗
PubMed2006

Gaucher disease and the synucleinopathies.

Several recent observations suggest a connection between Gaucher disease, the inherited deficiency of glucocerebrosidase, and the synucleinopathies. Rare patients have been observed who develop both Gaucher disease and parkinsonism. Autopsy studies on these subjects reveal synuclein-positive Lewy bodies and inclusions. An increased incidence of synucleinopathies also has been noted in relatives of Gaucher probands. In complementary studies, screening of patients with parkinsonism has identified a greater than expected frequency of glucocerebrosidase mutations. These glucocerebrosidase mutation carriers have a wide spectrum of associated parkinsonian phenotypes, ranging from classic L-dopa-responsive Parkinson disease to a phenotype more characteristic of Lewy body dementia. Despite this association, the vast majority of Gaucher carriers and patients with Gaucher disease never develop parkinsonism. However, mutations in this gene are likely to be a contributing risk factor in subjects otherwise prone to developing synucleinopathies.

Journal Article↗
PubMed2005

Support for association between ADHD and two candidate genes: NET1 and DRD1.

Attention deficit hyperactivity disorder (ADHD) is a common, multifactorial disorder with significant genetic contribution. Multiple candidate genes have been studied in ADHD, including the norepinephrine transporter (NET1) and dopamine D1 receptor (DRD1). NET1 is implicated in ADHD because of the efficacy of atomoxetine, a selective noradrenergic reuptake inhibitor, in the treatment of ADHD. DRD1 is primarily implicated through mouse models of ADHD. DNA from 163 ADHD probands, 192 parents, and 129 healthy controls was used to investigate possible associations between ADHD and polymorphisms in 12 previously studied candidate genes (5-HT1B, 5-HT2A, 5-HT2C, ADRA2A, CHRNA4, COMT, DAT1, DRD1, DRD4, DRD5, NET1, and SNAP-25). Analyses included case-control and family-based methods, and dimensional measures of behavior, cognition, and anatomic brain magnetic resonance imaging (MRI). Of the 12 genes examined, two showed a significant association with ADHD. Transmission disequilibrium test (TDT) analysis revealed significant association of two NET1 single nucleotide polymorphisms (SNPs) with ADHD (P < or = 0.009); case-control analysis revealed significant association of two DRD1 SNPs with ADHD (P < or = 0.008). No behavioral, cognitive, or brain MRI volume measurement significantly differed across NET1 or DRD1 genotypes at an alpha of 0.01. This study provides support for an association between ADHD and polymorphisms in both NET1 and DRD1; polymorphisms in ten other candidate genes were not associated with ADHD. Because family-based and case-control methods gave divergent results, both should be used in genetic studies of ADHD.

Adolescent↗
PubMed2005

Gaucher mutation N188S is associated with myoclonic epilepsy.

The recent article by Montfort et al. [2004] reported a functional analysis of 13 glucocerebrosidase alleles, including mutation N188S, which they considered to be a "very mild mutation" or "modifier variant." Our clinical experience with patients carrying this mutation and preliminary protein modeling data lead us to dispute this conclusion.

Adolescent↗
PubMed2005

Enhanced calcium release in the acute neuronopathic form of Gaucher disease.

Gaucher disease is an inherited metabolic disorder caused by defective activity of the lysosomal enzyme, glucocerebrosidase, resulting in accumulation of the lipids, glucosylceramide (GlcCer), and glucosylsphingosine (GlcSph). Little is known about the mechanism leading from lipid accumulation to disease, particularly in the acute and subacute neuronopathic forms of Gaucher disease, types 2 and 3, respectively. Recent work from our laboratory has shown, in animal models, that GlcCer enhances agonist-induced calcium release from intracellular stores via the ryanodine receptor, which results in neuronal cell death. We now test whether calcium release is altered in human brain tissue obtained post-mortem from Gaucher disease patients. Agonist-induced calcium release via the ryanodine receptor was significantly enhanced (P < 0.05) in brain microsomes from the acute neuronopathic form of Gaucher disease (type 2) (43 +/- 6% of the calcium in microsomes) compared to the subacute (type 3) (27 +/- 3%) and the non-neuronopathic (type 1) (28 +/- 6%) forms, and controls (18 +/- 3%), and correlated with levels of GlcCer accumulation. These findings suggest that defective calcium homeostasis may be a mechanism responsible for neuropathophysiology in acute neuronopathic Gaucher disease, and may potentially offer new therapeutic approaches for disease management.

Acute Disease↗
PubMed2004

A novel alteration in metaxin 1, F202L, is associated with N370S in Gaucher disease.

The gene for glucocerebrosidase ( GBA), the enzyme deficient in Gaucher disease, is located in a gene-rich region on 1q21. Metaxin 1( MTX1) is a convergently transcribed gene contiguous to the 3' end of the GBA pseudogene. A single nucleotide alteration in MTX1, 628T-->C, resulting in the amino acid change F202L, was identified in patients with Gaucher disease in association with the common N370S mutation in GBA. The polymorphism was also present on 4.6% of 152 control alleles, but could have functional consequences that have a modifying role in Gaucher disease.

Case-Control Studies↗
PubMed2004

Glucocerebrosidase mutations in subjects with parkinsonism.

Recent studies showing an association between glucocerebrosidase deficiency and parkinsonism in Gaucher disease prompted an examination of the glucocerebrosidase gene sequence (GBA) and enzyme activity in brain samples from 57 subjects carrying the diagnosis of Parkinson disease. Alterations in GBA were identified in 12 samples (21%) and were more frequent among the younger subjects. These included eight with mutations (N370S, L444P, K198T, and R329C) and four with probable polymorphisms (T369M and E326K). Our findings suggest that mutations in glucocerebrosidase may be a risk factor for the development of parkinsonism.

Adult↗
PubMed2004

Neuropathology provides clues to the pathophysiology of Gaucher disease.

To better understand the pathogenesis of brain dysfunction in Gaucher disease (GD), we studied brain pathology in seven subjects with type 1 GD (four also exhibited parkinsonism and dementia), three with type 2 GD and four with type 3 GD. Unique pathologic patterns of disease involving the hippocampal CA2-4 regions and layer 4b of the calcarine cortex were identified. While these findings were common to all three GD phenotypes, the extent of the changes varied depending on the severity of disease. Cerebral cortical layers 3 and 5, hippocampal CA2-4, and layer 4b were involved in all GD patients. Neuronal loss predominated in both type 2 and type 3 patients with progressive myoclonic encephalopathy, whereas patients classified as type 1 GD had only astrogliosis. Adjacent regions and lamina, including hippocampal CA1 and calcarine lamina 4a and 4c were spared of pathology, highlighting the specificity of the vulnerability of selective neurons. Elevated glucocerebrosidase expression by immunohistochemistry was found in CA2-4. Hippocampal (45)Ca(2+) uptake autoradiography in rat brain was performed demonstrating that hippocampal CA2-4 neurons, rather than CA1 neurons, were calcium-induced calcium release sensitive (CICR-sensitive). These findings match recent biochemical studies linking elevated glucosylceramide levels to sensitization of CA2-4 RyaR receptors and 300% potentiation of neuronal CICR sensitivity. In two patients with type 1 GD and parkinsonism, numerous synuclein positive inclusions, similar to brainstem-type Lewy bodies found in Parkinson disease, were also found hippocampal CA2-4 neurons. These findings argue for a common cytotoxic mechanism linking aberrant glucocerebrosidase activity, neuronal cytotoxicity, and cytotoxic Lewy body formation in GD.

Adolescent↗
PubMed2003

Reciprocal and nonreciprocal recombination at the glucocerebrosidase gene region: implications for complexity in Gaucher disease.

Gaucher disease results from an autosomal recessive deficiency of the lysosomal enzyme glucocerebrosidase. The glucocerebrosidase gene is located in a gene-rich region of 1q21 that contains six genes and two pseudogenes within 75 kb. The presence of contiguous, highly homologous pseudogenes for both glucocerebrosidase and metaxin at the locus increases the likelihood of DNA rearrangements in this region. These recombinations can complicate genotyping in patients with Gaucher disease and contribute to the difficulty in interpreting genotype-phenotype correlations in this disorder. In the present study, DNA samples from 240 patients with Gaucher disease were examined using several complementary approaches to identify and characterize recombinant alleles, including direct sequencing, long-template polymerase chain reaction, polymorphic microsatellite repeats, and Southern blots. Among the 480 alleles studied, 59 recombinant alleles were identified, including 34 gene conversions, 18 fusions, and 7 downstream duplications. Twenty-two percent of the patients evaluated had at least one recombinant allele. Twenty-six recombinant alleles were found among 310 alleles from patients with type 1 disease, 18 among 74 alleles from patients with type 2 disease, and 15 among 96 alleles from patients with type 3 disease. Several patients carried two recombinations or mutations on the same allele. Generally, alleles resulting from nonreciprocal recombination (gene conversion) could be distinguished from those arising by reciprocal recombination (crossover and exchange), and the length of the converted sequence was determined. Homozygosity for a recombinant allele was associated with early lethality. Ten different sites of crossover and a shared pentamer motif sequence (CACCA) that could be a hotspot for recombination were identified. These findings contribute to a better understanding of genotype-phenotype relationships in Gaucher disease and may provide insights into the mechanisms of DNA rearrangement in other disorders.

Amino Acid Substitution↗
PubMed2003

Gaucher disease associated with parkinsonism: four further case reports.

Type 1 Gaucher disease is considered the non-neuronopathic form of this autosomal recessively inherited lysosomal storage disease. We report the simultaneous occurrence of Gaucher disease with parkinsonian in four adult patients. The patients had a relatively early onset of parkinsonian manifestations, and their disease was rapidly progressive and refractory to therapy. Each had a different Gaucher genotype, although four alleles carried the common N370S mutation. No mutations were identified in the genes for parkin or alpha-synuclein. The concurrence of these two phenotypes, both in this series of patients and in others in the literature, suggests a shared pathway, modifier, or other genetic etiology.

Alleles↗
PubMed2003

Phenotypic continuum in neuronopathic Gaucher disease: an intermediate phenotype between type 2 and type 3.

Neuronopathic Gaucher disease, classically divided into two types, can have a continuum of phenotypes, often defying categorization. Nine children had an intermediate phenotype characterized by a delayed age of onset but rapidly progressive neurological disease, including refractory seizures and oculomotor abnormalities. There was genotypic heterogeneity among these patients.

Age of Onset↗
PubMed2003

Myoclonic epilepsy in Gaucher disease: genotype-phenotype insights from a rare patient subgroup.

Gaucher disease, the inherited deficiency of lysosomal glucocerebrosidase, presents with a wide spectrum of manifestations. Although Gaucher disease has been divided into three clinical types, patients with atypical presentations continue to be recognized. A careful phenotypic and genotypic assessment of patients with unusual symptoms may help define factors that modify phenotype in this disorder. One such example is a rare subgroup of patients with type 3 Gaucher disease who develop progressive myoclonic epilepsy. We evaluated 16 patients with myoclonic epilepsy, nine of whom were diagnosed by age 4 y with severe visceral involvement and myoclonus, and seven with a more chronic course, who were studied between ages 22 and 40. All of the patients had abnormal horizontal saccadic eye movements. Fourteen different genotypes were encountered, yet there were several shared alleles, including V394L (seen on two alleles), G377S (seen on three alleles), and L444P, N188S, and recombinant alleles (each found on four alleles). V394L, G377S, and N188S are mutations that have previously been associated with non-neuronopathic Gaucher disease. The spectrum of genotypes differed significantly from other patients with type 3 Gaucher disease, where genotypes L444P/L444P and R463C/null allele predominated. Northern blot studies revealed a normal glucocerebrosidase transcript, whereas Western studies showed that the patients studied lacked the processed 56 kD isoform of the enzyme, consistent with neuronopathic Gaucher disease. Brain autopsy samples from two patients demonstrated elevated levels of glucosylsphingosine, a toxic glycolipid, which could contribute to the development of myoclonus. Thus, although there were certain shared mutant alleles found in these patients, both the lack of a shared genotype and the variability in clinical presentations suggest that other modifiers must contribute to this rare phenotype.

Adolescent↗
PubMed2002

A deletion-insertion mutation in the phosphomannomutase 2 gene in an African American patient with congenital disorders of glycosylation-Ia.

Congenital disorders of glycosylation (CDG) are a group of metabolic disorders with multisystemic involvement characterized by abnormalities in the synthesis of N-linked oligosaccharides. The most common form, CDG-Ia, resulting from mutations in the gene encoding the enzyme phosphomannomutase (PMM2), manifests with severe abnormalities in psychomotor development, dysmorphic features and visceral involvement. While this disorder is panethnic, we present the first cases of CDG-Ia identified in an African American family with two affected sisters. The proband had failure to thrive in infancy, hypotonia, ataxia, cerebellar hypoplasia and developmental delay. On examination, she also exhibited strabismus, inverted nipples and an atypical perineal fat distribution, all features characteristic of CDG-Ia. Direct sequencing demonstrated that the patient had a unique genotype, T237M/c.565-571 delAGAGAT insGTGGATTTCC. The novel deletion-insertion mutation, which was confirmed by subcloning and sequencing of each allele, introduces a stop codon 11 amino acids downstream from the site of the deletion. The presence of this deletion-insertion mutation at cDNA position 565 suggests that this site in the PMM2 gene may be a hotspot for chromosomal breakage.

Base Sequence↗
PubMed2002

Glucosylsphingosine accumulation in tissues from patients with Gaucher disease: correlation with phenotype and genotype.

Gaucher disease, the inherited deficiency of lysosomal glucocerebrosidase, presents with a wide spectrum of clinical manifestations including neuronopathic and non-neuronopathic forms. While the lipid glucosylceramide is stored in both patients with Gaucher disease and in a null allele mouse model of Gaucher disease, elevated levels of a second potentially toxic substrate, glucosylsphingosine, are also found. Using high performance liquid chromatography, glucosylsphingosine levels were measured in tissues from patients with type 1, 2, and 3 Gaucher disease. Glucosylsphingosine was measured in 16 spleen samples (8 type 1; 4 type 2; and 4, type 3) and levels ranged from 54 to 728 ng/mg protein in the patients with type 1 disease, 133 to 1200 ng/mg protein in the patients with type 2, and 109 to 1298 ng/mg protein in the type 3 samples. The levels of splenic glucosylsphingosine bore no relation to the type of Gaucher disease, the age of the patient, the genotype, nor the clinical course. In the same patients, hepatic glucosylsphingosine levels were lower than in spleen. Glucosylsphingosine was also measured in brains from 13 patients (1 type 1; 8 type 2; and 4 type 3). While the glucosylsphingosine level in the brain from the type 1 patient, 1.0 ng/mg protein, was in the normal range, the levels in the type 3 samples ranged from 14 to 32 ng/mg protein, and in the type 2 samples from 24 to 437 ng/mg protein, with the highest values detected in two fetuses with hydrops fetalis. The elevated levels found in brains from patients with neuronopathic Gaucher disease support the hypothesis that glucosylsphingosine may contribute to the nervous system involvement in these patients.

Adolescent↗