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S M Pulst

Publications and source records attributed to S M Pulst.

At least 55 records · Page 3Linked to original sources
PubMed1998

Clinical and genetic analysis of a distinct autosomal dominant spinocerebellar ataxia.

OBJECTIVE: To characterize a distinct form of spinocerebellar ataxia (SCA) clinically and genetically. BACKGROUND: The SCAs are a genetically heterogeneous group of neurodegenerative disorders affecting the cerebellum and its connections. The mutations for SCA1, 2, 3, 6, and 7 have been identified and shown to be due to expansion of a CAG repeat in the coding region of these genes. Two additional SCA loci on chromosomes 16 and 11 have been designated SCA4 and SCA5. However, up to 20% of individuals with autosomal dominant forms of ataxias cannot be assigned any of these genotypes, implying the presence of other unidentified genes that may be involved in the development of ataxia. METHODS: We ascertained and clinically characterized a six-generation pedigree segregating an autosomal dominant trait for SCA. We performed direct mutation analysis and linkage analysis for all known SCA loci. RESULTS: The mutation analysis excludes SCA1, 2, 3, 6, and 7, and genetic linkage analysis excludes SCA4 and SCA5 (multipoint location scores < -2 across the candidate region). Clinical analysis of individuals in this family shows that all affected members have dysarthria, gait and limb ataxia, and nystagmus. No individuals have major brainstem or long-tract findings. Analysis of age at disease onset through multiple generations suggests anticipation. CONCLUSION: This pedigree represents a genetically distinct form of SCA with a phenotype characterized by predominantly cerebellar symptoms and signs.

Adult↗
PubMed1997

A high-resolution PAC and BAC map of the SCA2 region.

The spinocerebellar ataxia type 2 (SCA2) gene has been localized to chromosome 12q24.1. To characterize this region and to aid in the identification of the SCA2 gene, we have constructed a 3.9-Mb physical map, which covers markers D12S1328 and D12S1329 known to flank the gene. The map comprises a contig of 84 overlapping yeast artificial chromosomes (YACs), P1 artificial chromosomes (PACs), and bacterial artificial chromosomes (BACs) onto which we placed 82 PCR markers. We localized eight genes and expressed sequence tags on this map, many of which had not been precisely mapped before. In contrast to YACs, which showed a high degree of chimerism and deletions in this region, PACs and BACs were stable. Only 1 in 65 PACs contained a small deletion, and 2 in 18 BACs were chimeric. The high-resolution physical map, which was used in the identification of the SCA2 gene, will be useful for the positional cloning of other disease genes mapped to this region.

Ataxins↗
PubMed1997

Spinocerebellar ataxia type 2. Genotype and phenotype in German kindreds.

BACKGROUND: Spinocerebellar ataxia type 2 (SCA2) is an autosomal dominant cerebellar ataxia (ADCA) for which the disease-causing mutation has recently been characterized as an expanded CAG trinucleotide repeat. We investigated 64 families of German ancestry with ADCA and 55 patients with sporadic ataxia for the SCA2 mutation. RESULTS: Expanded alleles were found in 6 of the 64 families and in 1 patient with sporadic ataxia. This patient had a de novo mutation from an intermediate paternal allele. Length of repeats in 21 patients with SCA2 ranged from 36 to 52 CAG motifs and was inversely correlated with age at onset and progression of the disease. Expanded alleles were unstable during meiosis; paternal transmission especially caused significant anticipation of onset up to 26 years earlier. The SCA2 phenotype differed from those of SCA1 and SCA3 with higher frequencies of slowed ocular movements, postural and action tremor, myoclonus, and hyporeflexia. However, no single feature was sufficient to permit a specific clinical diagnosis. CONCLUSIONS: Spinocerebellar ataxia type 2 accounts for about 10% of German families with ADCA but may also be present in sporadic ataxia due to de novo mutations. Clinical features are highly variable among and even within families. However, the size of the expanded repeat influences the phenotype and is relevant for course and prognosis of the disease.

Adolescent↗
PubMed1997

SCA2 trinucleotide expansion in German SCA patients.

Autosomal dominant spinocerebellar ataxias (SCA) are a group of clinically and genetically heterogeneous neurodegenerative disorders which lead to progressive cerebellar ataxia. A gene responsible for SCA type 2 has been mapped to human chromosome 12 and the disease causing mutation has been identified as an unstable and expanded (CAG)n trinucleotide repeat. We investigated the (CAG)n repeat length of the SCA2 gene in 842 patients with sporadic ataxia and in 96 German families with dominantly inherited SCA which do not harbor the SCA1 or MJD1/SCA3 mutation, respectively. The SCA2 (CAG)n expansion was identified in 71 patients from 54 families. The (CAG)n stretch of the affected allele varied between 36 and 64 trinucleotide units. Significant repeat expansions occurred most commonly during paternal transmission. Analysis of the (CAG)n repeat lengths with the age of onset in 41 patients revealed an inverse correlation. Two hundred and forty-one apparently healthy octogenerians carried alleles between 16 and 31 repeats. One 50-year old, healthy individual had 34 repeats; she had transmitted an expanded allele to her child. The small difference between 'normal' and disease alleles makes it necessary to define the extreme values of their ranges. With one exception, the trinucleotide expansion was not observed in 842 ataxia patients without a family history of the disease. The SCA2 mutation causes the disease in nearly 14% of autosomal dominant SCA in Germany.

Adolescent↗
PubMed1997

Immunohistochemical detection of schwannomin and neurofibromin in vestibular schwannomas, ependymomas and meningiomas.

In addition to schwannomas, patients with neurofibromatosis type 2 (NF2) frequently develop meningiomas and occasionally, ependymomas. Using DNA and protein analyses, we have shown NF2 gene mutations and lack of the gene product schwannomin in 29 schwannomas, 10 meningiomas, and in 7 ependymomas. We have raised antibodies (ABs) to peptides from the C-terminal (5990-AB) and N-terminal (5991-AB) domains of schwannomin. The ABs specifically detected a 65 kDa protein in a Schwann cell line and recognized schwannomin in the cytoplasm of Schwann cells (SCH), perineurial cells, and vestibular ganglion neurons. None of the 29 schwannomas were stained by the 5990-AB. Only 4 schwannomas were stained by the 5991-AB, indicating that most truncated schwannomins were unstable or not expressed in schwannomas. Seven of 10 meningiomas, including 3 tumors from NF2 patients, were not stained by either 5990-AB or 5991-AB. Only 2 of 7 ependymomas lacked schwannomin. Complete lack of schwannomin in these tumors supports a tumor suppressor function for schwannomin in some meningiomas and ependymomas. All tumors showed staining with an antibody to a C-terminal peptide of neurofibromin, confirming that full-length neurofibromin is present in these vestibular schwannomas, meningiomas, and ependymomas. The presence of schwannomin in some meningiomas and in the majority of ependymomas indicates that additional genes are likely to play a role in tumorigenesis of these tumors.

Brain Neoplasms↗
PubMed1997

Neuronal expression and intracellular localization of presenilins in normal and Alzheimer disease brains.

The expression patterns of presenilin 1 (PS1) and presenilin 2 (PS2) in human normal and Alzheimer disease (AD) brains were investigated using antibodies to specific N-terminal peptides of PS1 (Alzh14A and Alzh14B) and PS2 (Alzh1A-AB). The antibodies to peptides Alzh14A (Alzh14A-AB) and Alzh14B (Alzh14B-AB) detected the full-length protein (approximately 63 kDa) and the N-terminal-processed fragment (36 kDa) of PS1, while the Alzh1A-AB detected mainly the N-terminal-processed fragment (36 kDa) of PS2. Immunofluorescent staining detected by confocal microscopy suggested that both native PS1 and PS2 are localized mainly in the Golgi/ER apparatus. Immunohistochemical studies of human temporal lobes from 2 normal and 5 sporadic Alzheimer brains revealed high levels of PS1 and PS2 expression in the granule cell layer and pyramidal neurons of the hippocampus. Strong immunoreactivity was found in reactive astrocytes and neurofibrillary tangles of all 5 Alzheimer brains. In contrast, only 2 sporadic Alzheimer brains showed presenilin-positive neuritic plaques. These observations suggest that presenilins may be involved in the pathology of some cases of sporadic AD.

Alzheimer Disease↗
PubMed1997

Atypical parkinsonism in a family of Portuguese ancestry: absence of CAG repeat expansion in the MJD1 gene.

We studied the clinical features and molecular genetics of a family, afflicted with a form of atypical parkinsonism, originating from the Madeira Islands of Portugal. We examined four affected individuals and reviewed clinical information on one other affected family member. Mean age at onset was 31 years. Parkinsonism (akinesia, rigidity, gait disturbance) was the most prominent feature in advanced disease. Levodopa responsiveness with peak-dose dyskinesia was present in one individual. Initial symptoms and other clinical features were variable and included other extrapyramidal signs (dystonia, action tremor of the limbs and bulbar muscles, synkinesis), ophthalmologic abnormalities (ptosis, slow saccades, progressive external ophthalmoplegia, hypometric saccades, saccadic pursuit movements), speech abnormalities (dysarthria, hypernasality), cortical impairment (dementia, frontal lobe dysfunction, palilalia, perseveration), minor cerebellar signs (dysmetria, gait ataxia), pyramidal abnormalities (spasticity, hyperreflexia), and peripheral nervous system abnormalities (propioceptive loss, areflexia, distal weakness, atrophy). The length of trinucleotide repeats in the MJD1 gene was in the normal range for all affected individuals.

Adult↗
PubMed1997

Clinical and molecular analysis of a pedigree of southern Italian ancestry with spinocerebellar ataxia type 2.

We describe patients from five generations of a pedigree with mutations in the spinocerebellar ataxia type 2 gene (SCA2). The predominant clinical features observed included both appendicular and truncal ataxia, dysarthria, slowness of saccades, and impaired optokinetic responses. Successive generations demonstrated both earlier ages of onset as well as increasing numbers of trinucleotide repeat sequences. The signs found in this family are compared with the description of other families with SCA2 as well as with other types of dominantly inherited spinocerebellar ataxias.

Adolescent↗
PubMed1997

Spinocerebellar ataxia type 6. Frequency of the mutation and genotype-phenotype correlations.

Spinocerebellar ataxia type 6 (SCA6) is the most recently identified mutation causing autosomal-dominant cerebellar ataxia without retinal degeneration (ADCA). The SCA6 mutation is allelic with episodic ataxia type 2 (EA-2), but the two differ clinically because of the presence of progressive, rather than episodic, ataxia in SCA6. SCA6 accounts for 12% of families with ADCA in an ethnically heterogeneous population of patients. Clinical examination, quantitative eye movement testing, and imaging data show that the brainstem is normal in most patients with SCA6, especially within the first 10 years of symptoms. Most patients show progressive ataxia from the onset, but several patients show an episodic course resembling EA-2. Thus, SCA6 mutations not only account for patients with ADCA I and ADCA III phenotypes but also for some patients presenting with episodic features that are typical for EA-2. Interestingly, a compound heterozygote for the SCA6 expansion manifested an earlier onset and more rapid course than family members with the same larger expanded allele.

Adolescent↗
PubMed1997

The prevalence and wide clinical spectrum of the spinocerebellar ataxia type 2 trinucleotide repeat in patients with autosomal dominant cerebellar ataxia.

The dominant cerebellar ataxias (ADCAs) represent a clinically and genetically heterogeneous group of disorders linked by progressive deterioration in balance and coordination. The utility of genetic classification of the ADCAs has been highlighted by the striking variability in clinical phenotype observed within families and the overlap in clinical phenotype observed between those with different genotypes. The recent demonstration that spinocerebellar ataxia type 2 (SCA2) is caused by a CAG repeat expansion within the ataxin-2 gene has allowed us to determine the frequency of SCA2 compared with SCA1, SCA3/Machado-Joseph disease (MJD), and dentatorubropallidoluysian atrophy (DRPLA) in patients with sporadic and inherited ataxia. SCA2 accounts for 13% of patients with ADCA (without retinal degeneration), intermediate between SCA1 and SCA3/MJD, which account for 6% and 23%, respectively. Together, SCA1, SCA2, and SCA3/MJD constitute >40% of the mutations leading to ADCA I in our population. No patient without a family history of ataxia, or with a pure cerebellar or spastic syndrome, tested positive for SCA1, SCA2, or SCA3. No overlap in ataxin-2 allele size between normal and disease chromosomes, or intermediate-sized alleles, were observed. Repeat length correlated inversely with age at onset, accounting for approximately 80% of the variability in onset age. Haplotype analysis provided no evidence for a single founder chromosome, and diverse ethnic origins were observed among SCA2 kindreds. In addition, a wide spectrum of clinical phenotypes was observed among SCA2 patients, including typical mild dominant ataxia, the MJD phenotype with facial fasciculations and lid retraction, and early-onset ataxia with a rapid course, chorea, and dementia.

Adolescent↗
PubMed1996

Characterization and expression of presenilin 1 in mouse brain.

The expression pattern of presenilin 1 (PS-1) in adult mouse brain was investigated using antibodies to specific peptides of PS-1. One antibody, Alz14A, specifically detected a 53 kDa protein in retinoic acid-treated P19 cells and mouse brain protein extracts consistent with the predicted PS-1 molecular weight. Immunohistochemical staining revealed that PS-1 was localized predominantly in large neurons in areas that were known to be affected by Alzheimer disease (AD) such as the hippocampal formation, entorhinal cortex and the subiculum. Selected neurons in other regions not known to be directly affected by AD, such as thalamic nuclei, Purkinje cells, large neurons in the brainstem and the gray matter of the spinal cord, and the dorsal root ganglion, also expressed PS-1. These observations suggest that other as yet identified factors might interact with mutated presenilins to cause neurodegeneration in AD-affected areas.

Animals↗
PubMed1996

Phenotypic variability in monozygotic twins with neurofibromatosis 2.

Mutations in the neurofibromatosis 2 (NF2) tumor suppressor gene on chromosome 22q12 cause a clinically variable autosomal dominant syndrome characterized by bilateral vestibular schwannomas (VSs), other nervous system tumors, and early onset lenticular cataracts. We studied three pairs of monozygotic (MZ) twins with NF2, all with bilateral VSs, to separate genetic from nongenetic causes of clinical variability. The evaluation included gadolinium-enhanced high-resolution magnetic resonance imaging of the head and spine, neuro-ophthalmic examination with slit lamp, physical examination, and zygosity testing with microsatellite markers. Each MZ pair was concordant for general phenotypic subtype (mild or severe) and often for the affected organ systems. However, the MZ pairs were discordant for some features of disease presentation or progression. For example, all three pairs were discordant for presence or type of associated cranial tumors. We hypothesize that phenotypic differences between NF2 MZ twins are at least partly due to stochastic processes, such as the loss of the second NF2 allele or alleles of other genes.

Adult↗
PubMed1996

Neurofibromatosis 2 antisense oligodeoxynucleotides induce reversible inhibition of schwannomin synthesis and cell adhesion in STS26T and T98G cells.

Mutations in the neurofibromatosis 2 (NF2) gene are the predominant cause in the development of sporadic schwannomas and are also involved in the pathogenesis of meningiomas and ependymomas. The product of the NF2 gene, termed merlin or schwannomin, is thought to act as a tumor suppressor protein. Although its protein sequence shows homology to proteins that are known to link the cytoskeleton to the cell membrane, no direct evidence for this function has been obtained. We used antisense phosphorothioate oligodeoxynucleotides (pODNs) complementary to the human NF2 cDNA sequence and transfected them into Schwann-like STS26T cells permeabilized by streptolysin 0. Changes in cell morphology and attachment were observed at 12 to 24 h and continued up to 48 h post transfection. Cells were rounded and easily dislodged from the substratum at 12-24 h. These changes were reversible and cells became bipolar with thin protrusions and began to reattach to the substratum after 48 h. Normal morphology and adhesion were observed at 72 h post transfection. Morphological changes were due to suppression of schwannomin synthesis. Immunoprecipitations with antischwannomin antibodies showed schwannomin to be almost absent 3 h after treatment with antisense pODNs and to be significantly suppressed up to 12 h post transfection whereas beta-actin levels remained unchanged. The morphological changes were not the result of cell death, but resulted in increased cell proliferation. These data demonstrate that antisense oligonucleotides can be successfully employed to suppress schwannomin synthesis and indicate that schwannomin may belong to a class of tumor suppressor genes that provide a link between cell adhesion and tumorigenesis.

Amino Acid Sequence↗
PubMed1996

Identification of three neurofibromatosis type 2 (NF2) gene mutations in vestibular schwannomas.

Vestibular schwannomas (VSs) are common benign tumors of Schwann cell origin and are frequently found in patients with neurofibromatosis type 2 (NF2). We analyzed 15 sporadic VSs for mutations in the tumors, two of which contained loss of heterozygosity (LOH). One of the tumors contained a novel mutation, a 19-bp deletion in exon 4. The two other tumors contained an identical mutation, a complete exon 4 deletion. The exon 4 deletion represents the second most frequently reported mutation of the NF2 gene in VSs.

Chromosome Deletion↗
PubMed1996

Identification of three new microsatellite markers in the spinocerebellar ataxia type 2 (SCA2) region and 1.2 Mb physical map.

Spinocerebellar ataxia type 2 (SCA2) is a neurodegenerative disease recently mapped to chromosome 12q close to the locus D12S84 by genetic linkage analysis. To generate additional genetic markers in the SCA2 region, we constructed a physical map of the region using yeast artificial chomosome (YAC), P1 artificial chromosome (PAC) and cosmid clones. The physical map was found to agree well with the genetic map. Three novel microsatellite markers were isolated and physically mapped. A novel approach to isolate CAG repeats directly from YAC DNAs is described.

Alleles↗
PubMed1996

Moderate expansion of a normally biallelic trinucleotide repeat in spinocerebellar ataxia type 2.

The gene for spinocerebellar ataxia type 2 (SCA2) has been mapped to 12q24.1. A 1.1-megabase contig in the candidate region was assembled in P1 artificial chromosome and bacterial artificial chromosome clones. Using this contig, we identified a CAG trinucleotide repeat with CAA interruptions that was expanded in patients with SCA2. In contrast to other unstable trinucleotide repeats, this CAG repeat was not highly polymorphic in normal individuals. In SCA2 patients, the repeat was perfect and expanded to 36-52 repeats. The most common disease allele contained (CAG)37, one of the shortest expansions seen in a CAG expansion syndrome. The repeat occurs in the 5'-coding region of SCA2 which is a member of a novel gene family.

Amino Acid Sequence↗
PubMed1996

The neuroimaging and clinical spectrum of neurofibromatosis 2.

Neurofibromatosis 2 (NF2) is an autosomal dominant disease predisposing to multiple tumors of the central and peripheral nervous system. Bilateral vestibular schwannomas are the hallmark of the disease. To define the clinical spectrum of the disease, we performed gadolinium-enhanced magnetic resonance imaging of the brain and spine as well as neurological, dermatological, and ocular examinations in 48 patients with NF2 diagnosed with the National Institutes of Health diagnostic criteria. Patients were ascertained from patient workshops and publications and from referral as a result of vestibular schwannoma surgery. Vestibular schwannomas were found in 46 patients (96%, 43 bilateral and 3 unilateral), spinal tumors were found in 43 (90%), posterior subcapsular cataracts were found in 30 (63%), meningiomas were found in 28 (58%), and trigeminal schwannomas were found in 14 (29%). The presenting symptoms included hearing loss or tinnitus in 15 patients (31%), multiple or nonspecific symptoms in 15 (31%), skin tumors in 12 (25%), and ocular symptoms in 6 (13%). When the complete spine was imaged, spinal tumors were more common in patients with NF2 than has previously been reported. This is a noteworthy finding, because spinal tumors are a major cause of NF2 morbidity and mortality.

Adolescent↗