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Nicholas W Wood

Publications and source records attributed to Nicholas W Wood.

At least 37 records · Page 2Linked to original sources
PubMed2005

Parkin disease in a Brazilian kindred: Manifesting heterozygotes and clinical follow-up over 10 years.

We report on a large Brazilian kindred with young-onset parkinsonism due to either a homozygous or heterozygous mutation in parkin. A total of 6 members were affected: 5 were homozygous and 1 heterozygous for a deletion in exon 4. Two other heterozygotes also had extrapyramidal signs. All affected subjects showed characteristic features of parkin disease with foot dystonia and an excellent response to levodopa complicated by motor fluctuations and dyskinesia within 3 years of therapy. Careful clinical follow-up over 10 years showed the phenotype was similar in all the homozygotes with asymmetrical limb bradykinesia and early walking difficulties. Some acceleration of disability was observed in some of the cases as they entered the third decade of illness, but dementia was absent.

Adult↗
PubMed2005

Parkinsonism and nigrostriatal dysfunction are associated with spinocerebellar ataxia type 6 (SCA6).

SCA6 is a slowly progressive, late-onset cerebellar ataxia due to a trinucleotide expansion in the CACNA1A gene. We describe two unrelated cases that presented with Parkinsonism and cerebellar ataxia. One case was L-dopa-responsive with a pattern of (18)F-dopa uptake similar to Parkinson's disease, and the second case was not L-dopa-responsive and had an atypical pattern of nigrostriatal dysfunction. We suggest that SCA6, in common with SCA2 and SCA3, may be associated with Parkinsonism attributable to nigral loss and dopaminergic dysfunction. Moreover, isolated cases may be confused with multiple system atrophy.

Adult↗
PubMed2005

UCHL-1 gene in multiple system atrophy: a haplotype tagging approach.

To date, the etiology of multiple system atrophy (MSA) has proved impenetrable. We investigated the role of genetic variation in the UCHL-1 gene in MSA and looked for the presence of disease susceptibility alleles. We determined the linkage disequilibrium structure of the gene and employed a haplotype tagging strategy with power to represent 95% of the haplotype diversity. This approach was performed using a set of tagging single nucleotide polymorphisms (SNPs) that can infer the allelic state of all the common SNPs in UCHL-1 with a high coefficient of determination. This strategy enabled us to scan across the gene and maintain the power to detect signal(s) from any potential functional variant(s). In 257 Gilman-probable or -definite MSA subjects and 1,536 controls, we did not detect a case-control frequency difference for either the tagged haplotypes or for individual tagging SNPs. This search included the S18Y variant of UCHL-1, which has been reported to be protective in Parkinson's disease.

Adult↗
PubMed2005

Synphilin-1 and parkin show overlapping expression patterns in human brain and form aggresomes in response to proteasomal inhibition.

Lewy bodies (LBs) are the characteristic inclusions of Parkinson's disease brain but the mechanism responsible for their formation is obscure. Lewy bodies (LBs) are composed of a number of proteins of which alpha-synuclein (alpha-SYN) is a major constituent. In this study, we have investigated the distribution patterns of synphilin-1 and parkin proteins in control and sporadic PD brain tissue by immunohistochemistry (IH), immunoblotting, and immunoelectron microscopy (IEM). We demonstrate the presence of synphilin-1 and parkin in the central core of a majority of LBs using IH and IEM. Using IH, we show an overlapping distribution profile of the two proteins in central neurons. Additionally, we show sensitivity of both endogenous synphilin-1 and parkin to proteolytic dysfunction and their co-localization in aggresomes formed in response to the proteasome inhibitor MG-132. We confirm that synphilin-1 and parkin are components of majority of LBs in Parkinson's disease and that both proteins are susceptible to proteasomal degradation.

Aged↗
PubMed2005

PARK11 is not linked with Parkinson's disease in European families.

Parkinson's disease (PD) is a genetically heterogeneous disease. Recently, significant linkage has been reported to a 39.5 cM region on the long arm of chromosome 2 (2q36-37; PARK11) in North American Parkinson families under an autosomal dominant model of inheritance. We have performed a replication study to confirm linkage to this region in a European population. Linkage analysis in 153 individuals from 45 European families with a strong family history of PD did not show any significant LOD score in this region. Therefore, PARK11 does not seem to play a major role for familial PD in the European population.

Chromosomes, Human, Pair 2↗
PubMed2005

Molecular genetic pathways in Parkinson's disease: a review.

Major progress has been made in the last decade in understanding the genetic basis of PD (Parkinson's disease) with five genes unequivocally associated with disease. As a result, multiple pathways have been implicated in the pathogenesis of PD, including proteasome impairment and mitochondrial dysfunction. Although Mendelian genetics has been successful in establishing a genetic predisposition for familial PD, this has not been reiterated in the sporadic form. In fact no genetic factors have been unequivocally associated with increased risk for sporadic PD. The difficulty in identifying susceptibility factors in PD has not only been because of numerous underpowered studies, but we have been unable to dissect out the genetic component in a multifactorial disease. This review aims to summarize the genetic findings within PD.

Chromosome Mapping↗
PubMed2004

A single-nucleotide polymorphism tagging set for human drug metabolism and transport.

Interindividual variability in drug response, ranging from no therapeutic benefit to life-threatening adverse reactions, is influenced by variation in genes that control the absorption, distribution, metabolism and excretion of drugs. We genotyped 904 single-nucleotide polymorphisms (SNPs) from 55 such genes in two population samples (European and Japanese) and identified a set of tagging SNPs that represents the common variation in these genes, both known and unknown. Extensive empirical evaluations, including a direct assessment of association with candidate functional SNPs in a new, larger population sample, validated the performance of these tagging SNPs and confirmed their utility for linkage-disequilibrium mapping in pharmacogenetics. The analyses also suggest that rare variation is not amenable to tagging strategies.

Cytochrome P-450 Enzyme System↗
PubMed2004

Causes of Parkinson's disease: genetics of DJ-1.

The identification of Mendelian mutations in rare forms of familial Parkinson's disease (PD) have provided significant insights into the molecular pathogenesis of this common complex disorder. DJ-1 is the third of four genes known to be definitively causal in familial PD, the three others being alpha-synuclein, parkin and the recently identified PINK1. Mutations in the DJ-1 gene were identified in two European families, a Dutch kindred harbouring a large homozygous genomic deletion encompassing exons 1-5 of the gene and an Italian kindred with a homozygous L166P missense mutation. The clinical phenotype of the two families was similar to that of parkin cases. Age of onset was in the mid-thirties with good responsiveness to l-dopa and slow disease progression. Focal dystonias and blepharospasm were also evident as were behavioural disturbances early in the course of the disease. To date, there are no studies of pathological material from known DJ-1 patients. It therefore remains to be determined whether these patients form Lewy bodies and/or Lewy neurites, the eosinophilic fibrillary inclusions that contain predominantly alpha-synuclein and that are the pathological hallmark of PD.

Genetic Linkage↗
PubMed2004

Genetic causes of Parkinson's disease: UCHL-1.

The ubiquitin proteasome system is an important cellular pathway that ubiquitinates damaged proteins and degrades them via the 26S proteasome. Abnormalities of this pathway can result in molecular protein aggregation and have been associated with Parkinson's disease (PD). UCHL-1, an enzyme central to the system, possesses catalytic hydrolase activity that can hydrolyze peptide-ubiquitin bonds and recycle ubiquitin monomers for re-use in the same process. Recently, UCHL-1 has been shown to possess a second dimerisation-dependent ligase activity and, at least in vitro, this ligase activity promotes alpha synuclein aggregation. UCHL-1 was first implicated in PD by the discovery of an I93M mutation identified in a German sib-pair with probable autosomal dominant PD. Although no further UCHL-1 mutations have been identified, a common non-synonymous S18Y polymorphism has been suggested to reduce disease susceptibility in non-mendelian forms of PD. In vitro functional data support this protective effect, with evidence that S18Y possesses reduced ligase activity compared with wild type UCHL-1. One study has found increased hydrolase activity associated with S18Y, although another study has not. Important issues regarding UCHL-1 and its role in PD remain inconclusive, especially regarding the pathogenicity of the mendelian I93M mutation. This review tries to address some of these uncertainties.

Humans↗
PubMed2004

Identifying candidate causal variants responsible for altered activity of the ABCB1 multidrug resistance gene.

The difficulty of fine localizing the polymorphisms responsible for genotype-phenotype correlations is emerging as an important constraint in the implementation and interpretation of genetic association studies, and calls for the definition of protocols for the follow-up of associated variants. One recent example is the 3435C>T polymorphism in the multidrug transporter gene ABCB1, associated with protein expression and activity, and with several clinical conditions. Available data suggest that 3435C>T may not directly cause altered transport activity, but may be associated with one or more causal variants in the poorly characterized stretch of linkage disequilibrium (LD) surrounding it. Here we describe a strategy for the follow-up of reported associations, including a Bayesian formalization of the associated interval concept previously described by Goldstein. We focus on the region of high LD around 3435C>T to compile an exhaustive list of variants by (1) using a relatively coarse set of marker typings to assess the pattern of LD, and (2) resequencing derived and ancestral chromosomes at 3435C>T through the associated interval. We identified three intronic sites that are strongly associated with the 3435C>T polymorphism. One of them is associated with multidrug resistance in patients with epilepsy (chi2 = 3.78, P = 0.052), and sits within a stretch of significant evolutionary conservation. We argue that these variants represent additional candidates for influencing multidrug resistance due to P-glycoprotein activity, with the IVS 26+80 T>C being the best candidate among the three intronic sites. Finally, we describe a set of six haplotype tagging single-nucleotide polymorphisms that represent common ABCB1 variation surrounding 3435C>T in Europeans.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2004

Somatic and germline mosaicism in sporadic early-onset Alzheimer's disease.

Alzheimer's disease (AD) is the commonest neurodegenerative disease worldwide. Rare familial cases may be caused by mutations in one of three genes-amyloid precursor protein, presenilin-1 and presenilin-2; however, the molecular basis of >99% of AD cases is unknown. Somatic mutation has been considered to be a mechanism that may account for a proportion of sporadic cases of AD, but to date there has been no evidence for this. We now report a sporadic early-onset patient with AD, and show that this individual is a somatic mosaic for a mutation in the presenilin-1 gene, suggesting a novel molecular mechanism for AD. Quantification of the mosaicism demonstrated the degree of mosaicism at 8% in peripheral lymphocytes and 14% in cerebral cortex in the index patient; a clear gene dosage effect on age of presentation and clinical phenotypic presentation is demonstrated. This finding has important implications for the aetiology of sporadic AD, and for other apparently sporadic neurodegenerative diseases such as Parkinson's disease, motor neuron disease and Creutzfeldt-Jakob disease.

Adult↗
PubMed2004

The structure of the tau haplotype in controls and in progressive supranuclear palsy.

The group of neurodegenerative diseases collectively known as tauopathies are characterized by hallmark lesions consisting of fibrillar aggregates of the microtubule-associated protein, tau (MAPT). Mutations of the tau gene (MAPT) are the cause of frontotemporal dementia with parkinsonism linked to chromosome 17, giving tau a central role in the pathogenic process. The chromosomal region containing MAPT has been shown to evolve into two major haplotypes, H1 and H2, which are defined by linkage disequilibrium (LD) between several polymorphisms over the entire MAPT gene. Studies to date suggest a complete absence of recombination between these two haplotypes. The more common haplotype H1 is over-represented in patients with progressive supranuclear palsy (PSP) and corticobasal degeneration. Using single nucleotide polymorphisms, we mapped LD in the regions flanking MAPT and have established the maximum extent of the haplotype block on chromosome 17q21.31 as a region covering approximately 2 Mb. This gene-rich region extends centromerically beyond the corticotrophin releasing hormone receptor 1 gene (CRHR1) to a region of approximately 400 kb, where there is a complete loss of LD. The telomeric end is defined by an approximately 150 kb region just beyond the WNT3 gene. We show that the entire, fully extended H1 haplotype is associated with PSP, which implicates several other genes in addition to MAPT, as candidate pathogenic loci.

Haplotypes↗
PubMed2004

Striatal and cortical pre- and postsynaptic dopaminergic dysfunction in sporadic parkin-linked parkinsonism.

To investigate striatal and cortical pre- and postsynaptic dopaminergic function in parkin-linked parkinsonism, 13 unrelated patients homozygous or compound heterozygous for parkin mutations were studied with [(18)F]dopa and [(11)C]raclopride (RAC) PET. Data were compared with a young-onset Parkinson's disease (YOPD) cohort, matched for age, disease severity and duration, but negative for parkin mutations. Significant changes in [(18)F]dopa uptake and RAC binding potential (BP) were localized in striatum using regions of interest (ROIs) and throughout the entire brain volume with statistical parametric mapping (SPM). As expected, both YOPD and parkin patients showed significant decreases in striatal [(18)F]dopa uptake; however, in parkin patients, additional reductions in caudate and midbrain were localized with SPM. The RAC-BP was significantly decreased in striatal, thalamic and cortical areas (temporal, orbito-frontal and parietal cortex) in parkin compared with YOPD patients. Our [(18)F]dopa PET findings suggest that, compared with YOPD, parkin disease is associated with more severe and widespread presynaptic dopaminergic deficits. The global decreases in D2 binding found in parkin compared with YOPD patients could be a direct consequence of the parkin genetic defect itself or a greater susceptibility to receptor downregulation following long-term dopaminergic agent exposure. Cortical reductions in D2 binding may contribute to the behavioural problems reported in parkin patients.

Adult↗
PubMed2004

Hereditary early-onset Parkinson's disease caused by mutations in PINK1.

Parkinson's disease (PD) is a neurodegenerative disorder characterized by degeneration of dopaminergic neurons in the substantia nigra. We previously mapped a locus for a rare familial form of PD to chromosome 1p36 (PARK6). Here we show that mutations in PINK1 (PTEN-induced kinase 1) are associated with PARK6. We have identified two homozygous mutations affecting the PINK1 kinase domain in three consanguineous PARK6 families: a truncating nonsense mutation and a missense mutation at a highly conserved amino acid. Cell culture studies suggest that PINK1 is mitochondrially located and may exert a protective effect on the cell that is abrogated by the mutations, resulting in increased susceptibility to cellular stress. These data provide a direct molecular link between mitochondria and the pathogenesis of PD.

Amino Acid Sequence↗
PubMed2004

A clinical, genetic and biochemical study of SPG7 mutations in hereditary spastic paraplegia.

Mutations in the SPG7 gene, encoding the mitochondrial protein paraplegin, were the first to be identified in autosomal recessive hereditary spastic paraplegia (ARHSP). Four different SPG7 mutations have been described so far in association with both pure and complicated HSP phenotypes. Muscle biopsies from the most severely affected patients have shown histological evidence of an oxidative phosphorylation defect. We identified six ARHSP kindreds, in whom linkage to SPG7 could not be excluded, and 29 sporadic spastic paraplegia patients. The 17 exons and flanking regions of the SPG7 gene were screened for mutations using a combination of single-stranded conformation polymorphism (SSCP) analysis and sequencing. Three patients were found to carry compound heterozygous SPG7 mutations, comprising five novel and one previously described mutation. Muscle biopsies from two SPG7 mutation patients did not show any histological evidence of an oxidative phosphorylation defect. However, biochemical analysis revealed a reduction in citrate synthase-corrected complex I and complex II/III activities in muscle and complex I activity in mitochondrial-enriched fractions from cultured myoblasts, suggesting that either a primary or a secondary defect of respiratory chain function may play an important role in the pathogenesis of the disease.

ATPases Associated with Diverse Cellular Activitie↗
PubMed2004

A functional polymorphism regulating dopamine beta-hydroxylase influences against Parkinson's disease.

A functional --1021C --> T polymorphism in the dopamine beta-hydroxylase gene has been demonstrated to regulate plasma DBH activity. We report that individuals with genetically determined low serum DBH activity (genotype T/T) have protection against Parkinson's disease (p = 0.01). In particular, we observed an underrepresentation of the T/T genotype odds ratio = 0.46 (CI = 0.27-0.8). Rather than identifying a haplotype, or a marker in linkage disequilibrium with the risk variant, this to our knowledge is the first report directly linking PD susceptibility with a proven functional variant.

Animals↗