Autosomal Dominant Forms Of Parkinson's Disease Research Articles

A novel alpha-synuclein G14R missense variant is associated with atypical neuropathological features.

Parkinson's disease (PD) affects millions of people worldwide, but only 5-10% of patients suffer from a monogenic form of the disease with Mendelian inheritance. SNCA, the gene encoding for the protein alpha-synuclein (aSyn), was the first to be associated with familial forms of PD and, since then, several missense variants and multiplications of the SNCA gene have been established as rare causes of autosomal dominant forms of PD. A patient carrying aSyn missense mutation and his family members were studied. We present the clinical features, genetic testing - whole exome sequencing (WES), and neuropathological findings. The functional consequences of this aSyn variant were extensively investigated using biochemical, biophysical, and cellular assays. The patient exhibited a complex neurodegenerative disease that included generalized myocloni, bradykinesia, dystonia of the left arm and apraxia. WES identified a novel heterozygous SNCA variant (cDNA 40G>A; protein G14R). Neuropathological examination showed extensive atypical aSyn pathology with frontotemporal lobar degeneration (FTLD) and nigral degeneration pattern with abundant ring-like neuronal inclusions, and few oligodendroglial inclusions. Sanger sequencing confirmed the SNCA variant in the healthy, elderly parent of the patient suggesting incomplete penetrance. NMR studies suggest that the G14R mutation induces a local structural alteration in aSyn, and lower thioflavin T binding in in vitro fibrillization assays. Interestingly, the G14R aSyn fibers display different fibrillar morphologies as revealed by cryo-electron microscopy. Cellular studies of the G14R variant revealed increased inclusion formation, enhanced membrane association, and impaired dynamic reversibility of serine 129 phosphorylation. The atypical neuropathological features observed, which are reminiscent of those observed for the G51D aSyn variant, suggest a causal role of the SNCA variant with a distinct clinical and pathological phenotype, which is further supported by the properties of the mutant aSyn, compatible with the strain hypothesis of proteinopathies.

VPS35 and retromer dysfunction in Parkinson's disease.

The vacuolar protein sorting 35 ortholog (VPS35) gene encodes a core component of the retromer complex essential for the endosomal sorting and recycling of transmembrane cargo. Endo-lysosomal pathway deficits are suggested to play a role in the pathogenesis of neurodegenerative diseases, including Parkinson's disease (PD). Mutations in VPS35 cause a late-onset, autosomal dominant form of PD, with a single missense mutation (D620N) shown to segregate with disease in PD families. Understanding how the PD-linked D620N mutation causes retromer dysfunction will provide valuable insight into the pathophysiology of PD and may advance the identification of therapeutics. D620N VPS35 can induce LRRK2 hyperactivation and impair endosomal recruitment of the WASH complex but is also linked to mitochondrial and autophagy-lysosomal pathway dysfunction and altered neurotransmitter receptor transport. The clinical similarities between VPS35-linked PD and sporadic PD suggest that defects observed in cellular and animal models with the D620N VPS35 mutation may provide valuable insights into sporadic disease. In this review, we highlight the current knowledge surrounding VPS35 and its role in retromer dysfunction in PD. We provide a critical discussion of the mechanisms implicated in VPS35-mediated neurodegeneration in PD, as well as the interplay between VPS35 and other PD-linked gene products. This article is part of a discussion meeting issue 'Understanding the endo-lysosomal network in neurodegeneration'.

Anionic lipid vesicles have differential effects on the aggregation of early onset-associated α-synuclein missense mutants

α-synuclein (αS) is the key component of synucleinopathies such as Parkinson's disease (PD), dementia with Lewy bodies, and multiple system atrophy. αS was first linked to PD through the identification of point mutations in the SNCA gene, causing single amino acid substitutions within αS and familial autosomal dominant forms of PD that profoundly accelerated disease onset by up to several decades. At least eight single-point mutations linked to familial PD (A30G/P, E46K, H50Q, G51D, and A53T/E/V) are located in proximity of the region preceding the non-β amyloid component (preNAC) region, strongly implicating its pathogenic role in αS-mediated cytotoxicity. Furthermore, lipids are known to be important for native αS function, where they play a key role in the regulation of synaptic vesicle docking to presynaptic membranes and dopamine transmission. However, the role of lipids in the function of mutant αS is unclear. Here, we studied αS aggregation properties of WT αS and five of the most predominant single-point missense mutants associated with early onset PD in the presence of anionic 1,2-dimyristoyl-sn-glycero-3-phospho-l-serine lipid vesicles. Our results highlight significant differences between aggregation rates, the number of aggregates produced, and overall fibril morphologies of WT αS and the A30P, E46K, H50Q, G51D, and A53T missense mutants in the presence of lipid vesicles. These findings have important implications regarding the interplay between the lipids required for αS function and the individual point mutations known to accelerate PD and related diseases.

Role of LRRK2 variant p.Gly2019Ser in patients with Parkinsonism.

Background & objectives:Parkinsonian disorder, including Parkinson's disease (PD), is an aetiologically complex neurodegenerative disorder. Mutations in leucine-rich repeat kinase 2 (LRRK2) gene have been implicated in an autosomal dominant form of PD with variable penetrance. The identification of a common LRRK2 variant (p.Gly2019Ser) in dementia with Lewy bodies indicated its potential role in Parkinsonian disorder. The current study was aimed to identify the p.Gly2019Ser variant in Indian patients with Parkinsonian disorder.Methods:The patient group consisting of 412 classical PD patients, 107 PD patients with cognitive impairment, 107 patients with Parkinson plus syndrome and 200 unrelated controls were recruited from eastern part of India. The allele representing p.Gly2019Ser variant was screened by polymerase chain reaction followed by restriction fragment length polymorphism analysis.Results:The p.Gly2019Ser variant was identified in an East Indian young-onset female PD patient in a heterozygous state having several motor and autonomic problems without disturbed cognition. Her younger brother, sister and elder son harbouring the same mutation were asymptomatic carriers for the variant. However, the influence of DNM3 on decreased disease onset in this family was not clear.Interpretation & conclusions:Identification of the p.Gly2019Ser variant in only one patient among a large number of Indian patients (n=626) with Parkinsonian disorder in our study suggests a limited role of the LRRK2 variant towards disease pathogenesis.

CHCHD2 mutational screening in Brazilian patients with familial Parkinson's disease.

Robust evidence on the involvement of genetic factors in the etiology of Parkinson's disease (PD) expands our knowledge about monogenic causes that contribute for this important neurodegenerative disorder. Mutations in the CHCHD2 gene have been linked to autosomal dominant forms of PD, although there is still lack of evidence for CHCHD2 variants leading to the disease in mixed populations as those from South America. To assess the contribution of CHCHD2 as a causal factor for familial PD in Brazil, one of the most heterogeneous populations in the world, we conducted the first molecular analysis of the CHCHD2 gene in a cohort of 122 index cases from Brazilian families with autosomal dominant forms of PD. Genomic DNA was isolated from peripheral blood and the 4 exons of the CHCHD2 gene, and their intron-exon boundaries were analyzed by bidirectional Sanger sequencing. No pathogenic or risk variants were found, suggesting that genetic variants of CHCHD2 are not a common cause of familial PD in Brazilian patients.

Exogenous LRRK2G2019S induces parkinsonian-like pathology in a nonhuman primate.

Parkinson's disease (PD) is the second most prevalent neurodegenerative disease among the elderly. To understand its pathogenesis and to test therapies, animal models that faithfully reproduce key pathological PD hallmarks are needed. As a prelude to developing a model of PD, we tested the tropism, efficacy, biodistribution, and transcriptional effect of canine adenovirus type 2 (CAV-2) vectors in the brain of Microcebus murinus, a nonhuman primate that naturally develops neurodegenerative lesions. We show that introducing helper-dependent (HD) CAV-2 vectors results in long-term, neuron-specific expression at the injection site and in afferent nuclei. Although HD CAV-2 vector injection induced a modest transcriptional response, no significant adaptive immune response was generated. We then generated and tested HD CAV-2 vectors expressing leucine-rich repeat kinase 2 (LRRK2) and LRRK2 carrying a G2019S mutation (LRRK2G2019S), which is linked to sporadic and familial autosomal dominant forms of PD. We show that HD-LRRK2G2019S expression induced parkinsonian-like motor symptoms and histological features in less than 4 months.

The Close Encounter Between Alpha-Synuclein and Mitochondria.

The presynaptic protein alpha-synuclein (α-syn) is unequivocally linked to the development of Parkinson’s disease (PD). Not only it is the major component of amyloid fibrils found in Lewy bodies but mutations and duplication/triplication in its gene are responsible for the onset of familial autosomal dominant forms of PD. Nevertheless, the precise mechanisms leading to neuronal degeneration are not fully understood. Several lines of evidence suggest that impaired autophagy clearance and mitochondrial dysfunctions such as bioenergetics and calcium handling defects and alteration in mitochondrial morphology might play a pivotal role in the etiology and progression of PD, and indicate the intriguing possibility that α-syn could be involved in the control of mitochondrial function both in physiological and pathological conditions. In favor of this, it has been shown that a fraction of cellular α-syn can selectively localize to mitochondrial sub-compartments upon specific stimuli, highlighting possible novel routes for α-syn action. A plethora of mitochondrial processes, including cytochrome c release, calcium homeostasis, control of mitochondrial membrane potential and ATP production, is directly influenced by α-syn. Eventually, α-syn localization within mitochondria may also account for its aggregation state, making the α-syn/mitochondria intimate relationship a potential key for the understanding of PD pathogenesis. Here, we will deeply survey the recent literature in the field by focusing our attention on the processes directly controlled by α-syn within mitochondrial sub-compartments and its potential partners providing possible hints for future therapeutic targets.

Genetics of Synucleinopathies.

Parkinson's disease (PD), diffuse Lewy body disease (DLBD), and multiple system atrophy (MSA) constitute the three major neurodegenerative disorders referred to as synucleinopathies because both genetic and pathological results implicate the α-synuclein protein in their pathogenesis. PD and DLBD are recognized as closely related diseases with substantial clinical and pathological overlap. MSA, on the other hand, has a distinctive clinical presentation and neuropathological profile. In this review, we will summarize the evidence linking α-synuclein to these three disorders. Hundreds of patients with point or copy number mutations in the gene encoding α-synuclein, SNCA, have been reported in the literature in association with hereditary, autosomal dominant forms of PD, DLBD, or neurodegenerative disease with parkinsonism. The copy number mutations show a dosage effect with age at onset and severity correlating with the number of extra copies of SNCA a patient carries. Common variation in and around the SNCA gene has also been found by genome-wide association studies to be associated with increased risk for apparently sporadic PD, with some evidence that these variants exert their effect through modest increases in α-synuclein expression. Complementing the genetic evidence linking α-synuclein to PD and DLBD is the pathological finding that α-synuclein is a major constituent of Lewy bodies and Lewy neurites in the brains of patients with the common sporadic form of PD. On the other hand, there is little genetic evidence linking SNCA to MSA despite strong neuropathological evidence of α-synuclein aggregation in oligodendroglial cells in MSA patients. Evidence is now emerging that α-synuclein aggregates can have different protein conformations, referred to as strains, similar to what has been shown in prion disease. The different phenotypes in hereditary PD/DLBD versus MSA are likely, therefore, to be the result not only of how specific mutations affect protein expression and turnover, but also a more complex interaction between intrinsic and extrinsic factors governing aggregation and strain formation.

Autosomal dominant Parkinson’s disease: Incidence of mutations in LRRK2, SNCA, VPS35 and GBA genes in Brazil

IntroductionAmongst Parkinson's disease (PD) genetic factors, mutations in LRRK2, SNCA, VPS35 and GBA genes are recognized causes of PD. Nonetheless, few genetic screenings have been conducted in families with a history of PD consistent with autosomal dominant inheritance (ADPD), and their relevance to the etiology of PD has been poorly explored in Latin American populations, such as the Brazilian one, with a high degree of admixture. MethodsIn order to assess the contribution of specific mutations in LRRK2, SNCA, VPS35 and GBA genes to ADPD in Brazil, we conducted the first molecular evaluation in a cohort of 141 index cases from families with ADPD. Genomic DNA was isolated from peripheral blood or saliva, and the molecular analysis was performed by TaqMan allelic discrimination assays or bidirectional sequencing. ResultsHeterozygous mutations in LRRK2 and GBA genes were identified in 10 (7.0%) probands, and all presented typical signs of classical PD. No mutations were found in SNCA or VPS35 genes. ConclusionOur findings in a representative series of index cases from families with ADPD emphasize the important contribution of LRRK2 G2019S and GBA (L444P and N370S) mutations to parkinsonism in Brazilian families. The absence of mutations in VPS35 and SNCA genes reveals that they are uncommon causes of PD in Brazil, corroborating previous studies that also failed to detect these genetic variants in PD patients from other populations. Recent discoveries of novel causative genes of autosomal dominant forms of PD expand the investigative possibilities and should be targeted on future studies.

Role of α-synuclein in inducing innate and adaptive immunity in Parkinson disease.

Alpha-synuclein (α-syn) is central to the pathogenesis of Parkinson disease (PD). Gene duplications, triplications and point mutations in SNCA1, the gene encoding α-syn, cause autosomal dominant forms of PD. Aggregated and post-translationally modified forms of α-syn are present in Lewy bodies and Lewy neurites in both sporadic and familial PD, and recent work has emphasized the prion-like ability of aggregated α-syn to produce spreading pathology. Accumulation of abnormal forms of α-syn is a trigger for PD, but recent evidence suggests that much of the downstream neurodegeneration may result from inflammatory responses. Components of both the innate and adaptive immune systems are activated in PD, and influencing interactions between innate and adaptive immune components has been shown to modify the pathological process in animal models of PD. Understanding the relationship between α-syn and subsequent inflammation may reveal novel targets for neuroprotective interventions. In this review, we examine the role of α-syn and modified forms of this protein in the initiation of innate and adaptive immune responses.

The chaperone-like protein 14-3-3η interacts with human α-synuclein aggregation intermediates rerouting the amyloidogenic pathway and reducing α-synuclein cellular toxicity.

Familial and idiopathic Parkinson's disease (PD) is associated with the abnormal neuronal accumulation of α-synuclein (aS) leading to β-sheet-rich aggregates called Lewy Bodies (LBs). Moreover, single point mutation in aS gene and gene multiplication lead to autosomal dominant forms of PD. A connection between PD and the 14-3-3 chaperone-like proteins was recently proposed, based on the fact that some of the 14-3-3 isoforms can interact with genetic PD-associated proteins such as parkin, LRRK2 and aS and were found as components of LBs in human PD. In particular, a direct interaction between 14-3-3η and aS was reported when probed by co-immunoprecipitation from cell models, from parkinsonian brains and by surface plasmon resonance in vitro. However, the mechanisms through which 14-3-3η and aS interact in PD brains remain unclear. Herein, we show that while 14-3-3η is unable to bind monomeric aS, it interacts with aS oligomers which occur during the early stages of aS aggregation. This interaction diverts the aggregation process even when 14-3-3η is present in sub-stoichiometric amounts relative to aS. When aS level is overwhelmingly higher than that of 14-3-3η, the fibrillation process becomes a sequestration mechanism for 14-3-3η, undermining all processes governed by this protein. Using a panel of complementary techniques, we single out the stage of aggregation at which the aS/14-3-3η interaction occurs, characterize the products of the resulting processes, and show how the processes elucidated in vitro are relevant in cell models. Our findings constitute a first step in elucidating the molecular mechanism of aS/14-3-3η interaction and in understanding the critical aggregation step at which 14-3-3η has the potential to rescue aS-induced cellular toxicity.

Frequency of the ASP620ASN mutation in VPS35 and Arg1205His mutation in EIF4G1 in familial Parkinson's disease from South Italy

Parkinson's disease (PD) is characterized by progressive loss of dopaminergic neurons in the substantia nigra pars compacta. This degeneration leads to bradykinesia, muscular rigidity, resting tremor, and postural instability. It affects 1%–2% of the population above the age of 60 years. Recently, 2 studies identified the Asp620Asn mutation in the vacuolar protein sorting 35 (VPS35) gene, and the Arg1205His in the eukaryotic translation initiation factor 4 gamma 1 gene (EIF4G1) were reported to be associated an autosomal dominant form of PD. In this study we screened these mutations in a cohort of 250 South Italy patients with familial PD and 250 control subjects from South Italy. VPS35 Asp620Asn mutation and EIF4G1 Arg1205His mutation were not found in our 250 PD patients. This result, with our previous reports on the absence of mutations in LRRK2 and in SNCA, warrant a continuing search for novel causative genes for PD among South Italy.

Casein Kinase II-mediated Phosphorylation Regulates α-Synuclein/Synphilin-1 Interaction and Inclusion Body Formation

Alpha-synuclein is a phosphoprotein that accumulates as a major component of Lewy bodies in the brains of patients with Parkinson disease. Synphilin-1, which is also present in Lewy bodies, binds with alpha-synuclein and forms cytoplasmic inclusions in transfected cells. Yet the molecular determinants of this protein-protein interaction are unknown. Here we report that casein kinase II (CKII) phosphorylates synphilin-1 and that the beta subunit of this enzyme complex binds to synphilin-1. Additionally, both CKII alpha and beta subunits are present within cytoplasmic inclusions in cells that overexpress synphilin-1. Notably, the interaction between synphilin-1 and alpha-synuclein is markedly dependent on phosphorylation. Inhibition of CKII activity by 5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole blocks the binding between these two proteins and significantly reduces the percentage of cells that contain eosinophilic cytoplasmic inclusions. Mutation of the major CKII phosphorylation site in alpha-synuclein (S129A) has no significant impact on the binding between alpha-synuclein and synphilin-1 or on the formation of synphilin-1/alpha-synuclein-positive inclusions. These data suggest that the CKII-mediated phosphorylation of synphilin-1 rather than that of alpha-synuclein is critical in modulating their tendency to aggregate into inclusions. These observations collectively indicate that a ubiquitous post-translational modification such as phosphorylation can regulate inclusion body formation in the context of alpha-synuclein and synphilin-1 interaction.

Impaired dopamine storage resulting from alpha-synuclein mutations may contribute to the pathogenesis of Parkinson's disease.

Parkinson's disease (PD) is a progressive neurodegenerative disorder characterized by the inability to initiate, execute and control movement. Neuropathologically, there is a striking loss of dopamine-producing neurons in the substantia nigra pars compacta, accompanied by depletion of dopamine in the striatum. Most forms of PD are sporadic, though in some cases familial inheritance is observed. In the late 1990s, two mutations in the alpha-synuclein gene were linked to rare, autosomal dominant forms of PD. Previously cloned from cholinergic vesicles of the Torpedo electric ray, alpha-synuclein is highly enriched in presynaptic nerve terminals and appears to be involved in synapse maintenance and plasticity. It is expressed ubiquitously in the brain, raising the important question of why dopaminergic neurons are primarily targeted in persons carrying mutations in alpha-synuclein. In this article, we review the current literature on alpha-synuclein and suggest a possible role for this protein in vesicle recycling via its regulation of phospholipase D2, its fatty acid-binding properties, or both. Exogenous application of dopamine, as well as redistribution of vesicular dopamine to the cytoplasm, can be toxic to dopaminergic neurons. Thus, impaired neurotransmitter storage arising from mutations in alpha-synuclein could lead to cytoplasmic accumulation of dopamine. The breakdown of this labile neurotransmitter in the cytoplasm could, in turn, promote oxidative stress and metabolic dysfunction, both of which have been observed in nigral tissue from PD patients.

Alpha -Synucleinopathy and selective dopaminergic neuron loss in a rat lentiviral-based model of Parkinson's disease.

Parkinson's disease (PD) is characterized by the progressive loss of substantia nigra dopaminergic neurons and the presence of cytoplasmic inclusions named Lewy bodies. Two missense mutations of the alpha-synuclein (alpha-syn; A30P and A53T) have been described in several families with an autosomal dominant form of PD. alpha-Syn also constitutes one of the main components of Lewy bodies in sporadic cases of PD. To develop an animal model of PD, lentiviral vectors expressing different human or rat forms of alpha-syn were injected into the substantia nigra of rats. In contrast to transgenic mice models, a selective loss of nigral dopaminergic neurons associated with a dopaminergic denervation of the striatum was observed in animals expressing either wild-type or mutant forms of human alpha-syn. This neuronal degeneration correlates with the appearance of abundant alpha-syn-positive inclusions and extensive neuritic pathology detected with both alpha-syn and silver staining. Lentiviral-mediated expression of wild-type or mutated forms of human alpha-syn recapitulates the essential neuropathological features of PD. Rat alpha-syn similarly leads to protein aggregation but without cell loss, suggesting that inclusions are not the primary cause of cell degeneration in PD. Viral-mediated genetic models may contribute to elucidate the mechanism of alpha-syn-induced cell death and allow the screening of candidate therapeutic molecules.

Refinement of the PARK3 locus on chromosome 2p13 and the analysis of 14 candidate genes.

Parkinson's disease (PD) is a common neurodegenerative disorder with clinical features of bradykinesia, rigidity, resting tremor and postural instability resulting from the deficiency of dopamine in the nigrostriatal system. Previously we mapped a susceptibility gene for an autosomal dominant form of PD to a 10.6 cM region of chromosome 2p (PARK3; OMIM 602404). A common haplotype shared by two North American kindreds (Families B and C) genealogically traced to Southern Denmark and Northern Germany suggested a founder effect. Here we report progress in the refinement of the PARK3 locus and sequence analysis of candidate genes within the region. Members of families B and C were genotyped using polymorphic markers, reducing the minimum common haplotype to eight markers spanning a physical distance of 2.5 Mb. Analysis of 14 genes within the region did not reveal any potentially pathogenic mutations segregating with the disease, implying that none of these genes are likely candidates for PARK3.

Progress in the clinical and molecular genetics of familial parkinsonism.

Parkinson's disease (PD) is a neurodegenerative disease with clinical features resulting from deficiency of dopamine in the nigrostriatal system. Most PD cases are sporadic and the primary cause of the disease is still unknown. Recently, familial PD and parkinsonism have received much attention because these forms of the disease might provide clues to the genetic risk factors involved in the pathogenesis of idiopathic PD. To date, two causative genes, alpha-synuclein and the parkin gene, have been identified. alpha-Synuclein is involved in the pathogenesis of an autosomal dominant form of PD and constitutes a major component of the Lewy body, which is a pathological hallmark of idiopathic PD. In addition, mutations in the parkin gene have been identified as the cause of autosomal recessive juvenile parkinsonism (AR-JP). AR-JP manifests itself as a highly selective degeneration of the substantia nigra and the locus coeruleus, but without Lewy body formation. In addition to these two genes, four chromosomal loci have been linked to other forms of familial PD. Furthermore, there are a number of other pedigrees of familial PD in which linkage to known genetic loci has been excluded. Molecular cloning of these disease genes and elucidation of the function of their gene products will greatly contribute to our understanding of the pathogenesis of idiopathic PD.

Intron-exon structure of ubiquitin c-terminal hydrolase-L1.

Parkinson's disease (PD) is a common neurodegenerative movement disorder characterized by tremor, bradykinesia, postural instability and muscular rigidity. Neuropathologically, it is defined by cell loss in the substantia nigra associated with the presence of intraneuronal inclusions called Lewy bodies (LB) and processes engorged with proteinaceous material, the Lewy neurites. The recent identification of mutations in the a-synuclein gene in some familial forms of PD 3 ' 6 and the demonstration of accumulation of the protein in Lewy bodies and Lewy neurites 7 suggest that abnormal protein aggregation may cause the disease. In addition to asynuclein, LBs contain ubiquitin, proteasomal subunits 2 and ubiquitin C-terminal hydrolase-Ll, 5 pointing to a potential participation of the ubiquitin-proteasome degradation pathway in the onset of the disease. We confirmed this hypothesis by identifying a missense mutation in the ubiquitin C-terminal hydrolase LI (UCH-L1) gene in a German family with an autosomal dominant form of PD. 4 UCH-L1 is highly specific for neurons and cells of the diffuse neuroendocrine system, and represents 1% to 5% of the total brain protein extract. 8 Northern blot analysis reveals a 1.3-kb brain-specific transcript broadly represented in all areas of the brain tested, particularly in the substantia nigra (Fig. 1). Enzymes belonging to the ubiquitin C-terminal hydrolases family can remove small amides and esters at the carboxyl terminus of ubiquitin and have been shown to hydrolyze peptides and small proteins similarly (reviewed in 9). They contribute to the pool of free monomeric ubiquitin molecules by hydrolysing the ubiquitin polymeric proprotein or ubiquitin-ribosomal fusion proteins during the maturation of the ribosome. 9 The Ile93Met mutation observed in 2 PD patients 4 causes a partial loss of catalytic activity of the UCH-L1 enzyme which could induce aberrations in the degradation pathway and lead to aggregation of proteins. To permit the rapid screening for mutations and assess the UCH-L1 role in PD, we have established specific amplification assays for all of its coding exons.