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Age is the greatest risk factor for many neurodegenerative diseases, yet immune system aging, a contributor to neurodegeneration, is understudied. Genetic variation in the LRRK2 gene affects risk for both familial and sporadic Parkinson's disease (PD). The leucine-rich repeat kinase 2 (LRRK2) protein is implicated in peripheral immune cell signaling, but the effects of an aging immune system on LRRK2 function remain unclear. We analyzed peritoneal macrophages from R1441C-Lrrk2 knock-in mice and observed a biphasic, age-dependent effect of the R1441C-Lrrk2 mutation on peritoneal macrophage function. We report increases in antigen presentation, anti-inflammatory cytokine production, lysosomal activity, and pathogen uptake in peritoneal macrophages from young (2- to 3-month-old) female R1441C-Lrrk2 mice. Conversely, macrophages from aged (18- to 21-month-old) female R1441C-Lrrk2 mice exhibited decreased antigen presentation after inflammatory insult, decreased lysosomal function, and pathogen uptake, with a concomitant increase in DNA fragmentation in the presence of pathogens. This immune cell exhaustion phenotype was not observed in male R1441C-Lrrk2 mice and was driven by increased LRRK2 protein kinase activity. This phenotype was also observed in human peripheral myeloid cells, with monocyte-derived macrophages from patients with PD who had either the R1441C- or Y1699C-LRRK2 mutation exhibiting decreased pathogen uptake and increased PDL1 expression, consistent with immune cell exhaustion. Our findings that LRRK2 mutations conferred an immunological advantage at a young age but could predispose the carrier to age-acquired immune cell exhaustion have implications for the therapeutic development of LRRK2 inhibitors.

Background: The role of ANO3 variants as a monogenic cause of dystonia is still under debate because of its relatively high frequency also in controls., Objective: To screen >1000 patients with movement disorders for rare ANO3 variants., Methods: We searched for rare ANO3 variants in 729 dystonia and 294 Parkinson's disease (PD) patients using a gene panel. Variants were validated by Sanger sequencing. For one variant carrier, family members were available for segregation analysis., Results: Nine carriers (seven with dystonia [1.0%], two with PD [0.7%]) of seven different rare, protein-changing variants were identified. None of these variants has been previously reported in dystonia patients. Two of the variants in dystonia patients were found recurrently: p.Arg328Cys was detected in two Korean and p.Arg969Gln in two German patients. The frequency of these two variants in our sample seemed to be higher as in ethnically matched samples from the Genome Aggregation Database (GnomAD). Further, we identified a patient with early-onset, generalized dystonia with a de-novo variant in ANO3 (p.Val561Glu). Of note, she benefitted from deep brain stimulation., Conclusion: This study confirms the relatively high frequency of rare, protein-changing ANO3 variants in both dystonia and non-dystonia patients indicating that not all variants contribute to the disease. Thus, disease relevance of novel variants remains difficult to interpret and functional studies are warranted for a better understanding of the role of ANO3 variants in dystonia. In contrast, de-novo variants in childhood-onset, generalized dystonia seem to represent an as yet underestimated phenotypic expression of changes in ANO3., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Objective: To identify novel causes of recessive ataxias, including spinocerebellar ataxia with saccadic intrusions, spastic ataxias, and spastic paraplegia., Methods: In an international collaboration, we independently performed exome sequencing in 7 families with recessive ataxia and/or spastic paraplegia. To evaluate the role of VPS13D mutations, we evaluated a Drosophila knockout model and investigated mitochondrial function in patient-derived fibroblast cultures., Results: Exome sequencing identified compound heterozygous mutations in VPS13D on chromosome 1p36 in all 7 families. This included a large family with 5 affected siblings with spinocerebellar ataxia with saccadic intrusions (SCASI), or spinocerebellar ataxia, recessive, type 4 (SCAR4). Linkage to chromosome 1p36 was found in this family with a logarithm of odds score of 3.1. The phenotypic spectrum in our 12 patients was broad. Although most presented with ataxia, additional or predominant spasticity was present in 5 patients. Disease onset ranged from infancy to 39 years, and symptoms were slowly progressive and included loss of independent ambulation in 5. All but 2 patients carried a loss-of-function (nonsense or splice site) mutation on one and a missense mutation on the other allele. Knockdown or removal of Vps13D in Drosophila neurons led to changes in mitochondrial morphology and impairment in mitochondrial distribution along axons. Patient fibroblasts showed altered morphology and functionality including reduced energy production., Interpretation: Our study demonstrates that compound heterozygous mutations in VPS13D cause movement disorders along the ataxia-spasticity spectrum, making VPS13D the fourth VPS13 paralog involved in neurological disorders. Ann Neurol 2018., (© 2018 American Neurological Association.)

Introduction: A latent nigrostriatal deficit and its possible clinical consequences in asymptomatic heterozygous Parkin and PINK1 mutation carriers (AMC) have been a matter of investigation in recent years. Notably, mild Parkinsonian signs in heterozygous mutation carriers can be so subtle that they may be missed if not specifically investigated., Methods: We studied 15 heterozygous Parkin and PINK1 AMC and 18 age- and sex-matched mutation-negative controls using a standardized video, instructing the probands to perform relevant parts of the UPDRS III to investigate fine motor movements at baseline and after first-time L-Dopa administration. Additionally, available UPDRS III scores of mutation carriers from the past ten years were reviewed., Results: AMC showed a reduced number of fine motor movements per second compared to controls at baseline (p = 0.04). L-Dopa improved motor performance numerically but non-significantly in AMC (p = 0.2301), but significantly in healthy controls (p = 6.1·10-5). Although none of the AMC reported symptoms, nine showed rigidity, bradykinesia, tremor, and postural instability when the UPDRS III was applied. Mean UPDRSIII scores significantly decreased after L-Dopa administration (p = 0.005), but did not increase over the past ten years., Conclusions: (i) Heterozygous AMC show subtle motor abnormalities when a detailed, specialized motor examination is applied and compared to mutation-negative matched control subjects. (ii) The mild motor deficit present in a subgroup of heterozygous Parkin and PINK1 AMC appears to be non-progressive and responsive to L-dopa administration. (iii) Evaluating motor changes, their progression, and treatment response in AMC can provide valuable insights into possible early disease stages and compensatory mechanisms., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Mutations in TUBB4A have been identified to cause a wide phenotypic spectrum ranging from hereditary generalized dystonia with whispering dysphonia (DYT4) to the leukodystrophy hypomyelination syndrome with atrophy of the basal ganglia and cerebellum (H-ABC). To test for the contribution of TUBB4A mutations in different ethnicities (Spanish, Italian, Korean, Japanese), we screened 492 isolated dystonia cases for mutations in this gene and for the first time determined TUBB4A copy number variations in 336 dystonia patients. A potentially pathogenic rare 3bp-in-frame deletion was found in a patient with cervical dystonia but no copy number variations were detected in this study, suggesting that TUBB4A mutations exceedingly rarely contribute to the etiology of isolated dystonia., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Objectives: Mutations in the Parkin and PINK1 gene account for the majority of autosomal recessive early-onset Parkinson cases. There is increasing evidence that clinically asymptomatic subjects with single heterozygous mutations have a latent nigrostriatal dopaminergic deficit and could be taken as in vivo model of pre-symptomatic phase of Parkinsonism., Methods: We charted premotor-motor excitability changes as compensatory mechanisms for subcortical dopamine depletions using transcranial magnetic stimulation by applying magnetic resonance-navigated premotor-motor cortex conditioning in 15 asymptomatic, heterozygous Parkin and PINK1 mutation carriers (2 female; mean age 53±8years) and 16 age- and sex-matched controls (5 female; mean age 57±9years). Participants were examined at baseline and after acute l-dopa challenge., Results: There were l-dopa and group specific effects during premotor-motor conditioning at an interstimulus interval of 6ms indicating a normalisation of premotor-motor interactions in heterozygous Parkin and PINK1 mutation carriers after l-dopa intake. Non-physiologically high conditioned MEP amplitudes at this interval in mutation carriers decreased after l-dopa intake but increased in controls., Conclusion: Premotor-motor excitability changes are part of the cortical reorganization in asymptomatic heterozygous Parkin- and PINK1 mutation carriers., Significance: These subjects offer opportunities to delineate motor network adaptation in pre-symptomatic Parkinsonism., (Copyright © 2016 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.)

Specific mutations in COL6A3 have recently been reported as the cause of isolated recessive dystonia, which is a rare movement disorder. In all patients, at least one mutation was located in Exons 41 and 42. In an attempt to replicate these findings, we assessed by direct sequencing the frequency of rare variants in Exons 41 and 42 of COL6A3 in 955 patients with isolated or combined dystonia or with another movement disorder with dystonic features. We identified nine heterozygous carriers of rare variants including five different missense mutations and an extremely rare synonymous variant. In these nine patients, we sequenced the remaining 41 coding exons of COL6A3 to test for a second mutation in the compound heterozygous state. In only one of them, a second rare variant was identified (Thr732Met + Pro3082Arg). Of note, this patient had been diagnosed with Parkinson´s disease (with dystonic posturing) due to homozygous PINK1 mutations. The COL6A3 mutations clearly did not segregate with the disease in the four affected siblings of this family. Further, there was no indication for a disease-modifying effect of the COL6A3 mutations since disease severity or age at onset did not correlate with the number of COL6A3 mutated alleles in this family. In conjunction with the relatively high frequency of homozygous carriers of reported mutations in publically available databases, our data call a causal role for variants in COL6A3 in isolated dystonia into question.

Importance: Mutations in the GNAL gene have recently been shown to cause primary torsion dystonia. The GNAL-encoded protein (Gαolf) is important for dopamine D1 receptor function and odorant signal transduction. We sequenced all 12 exons of GNAL in 461 patients from Germany, Serbia, and Japan, including 318 patients with dystonia (190 with cervical dystonia), 51 with hyposmia and Parkinson disease, and 92 with tardive dyskinesia or acute dystonic reactions., Observations: We identified the following two novel heterozygous putative mutations in GNAL: p.Gly213Ser in a German patient and p.Ala353Thr in a Japanese patient. These variants were predicted to be pathogenic in silico, were absent in ethnically matched control individuals, and impaired Gαolf coupling to D1 receptors in a bioluminescence energy transfer (BRET) assay. Two additional variants appeared to be benign because they behaved like wild-type samples in the BRET assay (p.Ala311Thr) or were detected in ethnically matched controls (p.Thr92Ala). Both patients with likely pathogenic mutations had craniocervical dystonia with onset in the fifth decade of life. No pathogenic mutations were detected in the patients with hyposmia and Parkinson disease, tardive dyskinesias, or acute dystonic reactions., Conclusions and Relevance: Mutations in GNAL can cause craniocervical dystonia in different ethnicities. The BRET assay may be a useful tool to support the pathogenicity of identified variants in the GNAL gene.

Dysfunctional mitochondria and the mitochondrial chaperone mortalin (HSPA9, GRP75) have been implicated in the pathogenesis of Parkinson disease (PD). We screened 139 early-onset PD (EOPD) patients for mutations in mortalin revealing one missense change (p.L358P) that was absent in 279 control individuals. We also found one additional missense variant among the controls (p.T333K). Although both missense changes were predicted to be disease causing, we detected no differences in subcellular localization, mitochondrial morphology, or respiratory function between wild-type and mutant mortalin. These findings suggest that variants in mortalin (1) are not a major cause of EOPD; (2) occur in patients and controls; and (3) do not lead to functional impairment of mitochondria., (Copyright © 2013 Elsevier Inc. All rights reserved.)

Objective: A study was undertaken to identify the gene underlying DYT4 dystonia, a dominantly inherited form of spasmodic dysphonia combined with other focal or generalized dystonia and a characteristic facies and body habitus, in an Australian family., Methods: Genome-wide linkage analysis was carried out in 14 family members followed by genome sequencing in 2 individuals. The index patient underwent a detailed neurological follow-up examination, including electrophysiological studies and magnetic resonance imaging scanning. Biopsies of the skin and olfactory mucosa were obtained, and expression levels of TUBB4 mRNA were determined by quantitative real-time polymerase chain reaction in 3 different cell types. All exons of TUBB4 were screened for mutations in 394 unrelated dystonia patients., Results: The disease-causing gene was mapped to a 23cM region on chromosome 19p13.3-p13.2 with a maximum multipoint LOD score of 5.338 at markers D9S427 and D9S1034. Genome sequencing revealed a missense variant in the TUBB4 (tubulin beta-4; Arg2Gly) gene as the likely cause of disease. Sequencing of TUBB4 in 394 unrelated dystonia patients revealed another missense variant (Ala271Thr) in a familial case of segmental dystonia with spasmodic dysphonia. mRNA expression studies demonstrated significantly reduced levels of mutant TUBB4 mRNA in different cell types from a heterozygous Arg2Gly mutation carrier compared to controls., Interpretation: A mutation in TUBB4 causes DYT4 dystonia in this Australian family with so-called whispering dysphonia, and other mutations in TUBB4 may contribute to spasmodic dysphonia. Given that TUBB4 is a neuronally expressed tubulin, our results imply abnormal microtubule function as a novel mechanism in the pathophysiology of dystonia., (Copyright © 2012 American Neurological Association.)

Objective: To describe excitability of motor pathways in Kufor-Rakeb syndrome (PARK9), an autosomal recessive nigro-striatal-pallidal-pyramidal neurodegeneration caused by a mutation in the ATP13A2 gene, using transcranial magnetic stimulation (TMS)., Methods: Five members of a Chilean family with an ATP13A2 mutation (one affected mutation carrier (MC) with a compound heterozygous mutation, 4 asymptomatic MC with a single heterozygous mutation) and 11 healthy subjects without mutations were studied. We measured motor evoked potentials (MEP), the contralateral silent period (cSP), short interval intracortical inhibition (SICI), intracortical facilitation (ICF), short latency afferent inhibition (SAI) as markers of intracortical intrahemispheric inhibition/facilitation and the ipsilateral silent period (iSP) and paired-pulse interhemispheric inhibition (IHI) to probe interhemispheric motor interactions., Results: CSP duration was increased in the symptomatic ATP13A2 MC. The iSP measurements revealed increased interhemispheric inhibition in both the compound heterozygous and the heterozygous MC., Conclusion: A compound heterozygous mutation in the ATP13A2 gene is associated with increased intracortical inhibition. In addition, some aspects of interhemispheric inhibition are increased in the presence of a single ATP13A2 mutation., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

Mutations in THAP1 have been associated with dystonia 6 (DYT6). THAP1 encodes a transcription factor that represses the expression of DYT1. To further evaluate the mutational spectrum of THAP1 and its associated phenotype, we sequenced THAP1 in 567 patients with focal (n = 461), segmental (n = 68), or generalized dystonia (n = 38). We identified 10 novel variants, including six missense substitutions within the DNA-binding Thanatos-associated protein domain (Arg13His, Lys16Glu, His23Pro, Lys24Glu, Pro26Leu, Ile80Val), a 1bp-deletion downstream of the nuclear localization signal (Asp191Thrfs*9), and three alterations in the untranslated regions. The effect of the missense variants was assessed using prediction tools and luciferase reporter gene assays. This indicated the Ile80Val substitution as a benign variant. The subcellular localization of Asp191Thrfs*9 suggests a disturbed nuclear import for this mutation. Thus, we consider six of the 10 novel variants as pathogenic mutations accounting for a mutation frequency of 1.1%. Mutation carriers presented mainly with early onset dystonia (<12 years in five of six patients). Symptoms started in an arm or neck and spread to become generalized in three patients or segmental in two patients. Speech was affected in four mutation carriers. In conclusion, THAP1 mutations are rare in unselected dystonia patients and functional analysis is necessary to distinguish between benign variants and pathogenic mutations.

To identify the underlying genetic cause in a consanguineous family with apparently recessively inherited dystonia, we performed genome-wide homozygosity mapping. This revealed 2 candidate regions including the THAP1 gene, where heterozygous mutations cause dystonia 6. A homozygous missense mutation in THAP1 (c.95T>A; p.Leu32His) was found in all 3 affected siblings. Symptoms started in childhood in the legs and became generalized within a few years. Three heterozygous mutation carriers were unaffected. Because THAP1 regulates the expression of the DYT1 gene, we used reporter gene assays to show that DYT1 expression was significantly increased for Leu32His. However, this increase was less pronounced than for other THAP1 mutations that cause dystonia in the heterozygous state. Our data suggest that homozygous THAP1 mutations cause dystonia and may be associated with a less severe dysfunction of the encoded protein compared with heterozygous disease-causing mutations., (Copyright © 2011 Movement Disorder Society.)

Background: Transcranial sonography (TCS) area of hyperechogenicity in the substantia nigra (aSN) is increased in idiopathic and genetic Parkinson's disease (PD)., Methods: We performed TCS in 34 LRRK2 G2019S mutation carriers manifesting PD, 24 non-manifesting mutation carriers, and 28 idiopathic PD patients and compared them with 40 healthy controls (total, n = 126)., Results: Compared with the controls (mean 0.15 cm(2) ), the aSN values in all other groups were increased. The mean aSN was 0.23 cm(2) in nonmanifesting mutation carriers (P = .015), 0.34 cm(2) in idiopathic PD patients (P < .0001), 0.32 cm(2) in LRRK2-associated PD patients (P < .0001), and 0.33 cm(2) in the overall PD group (P < .0001). LRRK2-associated PD patients had a higher aSN than did nonmanifesting carriers (P = .011), but there was no significant difference in aSN between patients with idiopathic and LRRK2-associated PD (P = .439)., Conclusions: Our results suggest that SN pathoanatomical alterations may not be substantially different between idiopathic and LRRK2-associated PD. The findings in the nonmanifesting mutation carriers suggest the presence of intermediate nigrostriatal pathology consistent with the age-dependent reduced penetrance of this mutation., (Copyright © 2011 Movement Disorder Society.)

PINK1 and Parkin mutations cause recessive Parkinson's disease (PD). In Drosophila and SH-SY5Y cells, Parkin is recruited by PINK1 to damaged mitochondria, where it ubiquitinates Mitofusins and consequently promotes mitochondrial fission and mitophagy.Here, we investigated the impact of mutations in endogenous PINK1 and Parkin on the ubiquitination of mitochondrial fusion and fission factors and the mitochondrial network structure. Treating control fibroblasts with mitochondrial membrane potential (Δψ) inhibitors or H(2)O(2) resulted in ubiquitination of Mfn1/2 but not of OPA1 or Fis1. Ubiquitination of Mitofusins through the PINK1/Parkin pathway was observed within 1 h of treatment. Upon combined inhibition of Δψ and the ubiquitin proteasome system (UPS), no ubiquitination of Mitofusins was detected. Regarding morphological changes, we observed a trend towards increased mitochondrial branching in PD patient cells upon mitochondrial stress.For the first time in PD patient-derived cells, we demonstrate that mutations in PINK1 and Parkin impair ubiquitination of Mitofusins. In the presence of UPS inhibitors, ubiquitinated Mitofusin is deubiquitinated by the UPS but not degraded, suggesting that the UPS is involved in Mitofusin degradation.

Objective: To determine clinical features and to identify changes in brain structure and function in compound heterozygous and heterozygous ATP13A2 mutation carriers., Design: Prospective multimodal clinical and neuroimaging study., Setting: University of Lübeck, Lübeck, Germany., Participants: Eight family members of a large Chilean pedigree with Kufor-Rakeb syndrome (KRS)., Interventions: Clinical characterization, dopamine transporter (DAT) imaging, voxel-based morphometry (VBM), and transcranial sonography (TCS)., Main Outcome Measures: Frequency of parkinsonian signs, brain structure, and functional alterations., Results: The only available patient with compound heterozygous KRS showed a markedly reduced striatal DAT density bilaterally. Magnetic resonance imaging revealed severe global brain atrophy as well as iron deposition in the basal ganglia. The heterozygous mother had definite parkinsonism with reduced DAT density in both putamina. While all asymptomatic heterozygous siblings displayed subtle extrapyramidal signs, DAT imaging revealed striatal tracer uptake within physiological levels. Voxel-based morphometry revealed an increase in gray matter volume in the right putamen and a decrease in the cerebellum of the heterozygous carriers. In all mutation carriers, the substantia nigra had a normal appearance on TCS., Conclusions: Single ATP13A2 heterozygous mutations may be associated with clinical signs of parkinsonism and contribute to structural and functional brain changes. Lack of hyperechogenicity in the substantia nigra may be a distinctive feature of this form of genetic parkinsonism. This, along with the finding of iron in the basal ganglia in our patient with KRS, implies a different underlying pathophysiology compared with other monogenic forms of parkinsonism and idiopathic PD and may place KRS among the syndromes of neurodegeneration with brain iron accumulation (NBIA).

Among the genes implicated for parkinsonism is glucocerebrosidase (GBA), which causes Gaucher disease (GD). Despite a growing literature that GD may present as parkinsonism, neuroimaging, olfaction, and neuropsychological testing have not been extensively reported. We describe transcranial sonography (TCS), 18F-fluorodopa (F-dopa) and fluorodeoxyglucose (FDG) Positron emission tomography, olfaction testing, neuropsychological testing, and clinical features in homozygous and compound heterozygous GBA mutation carriers identified through screening of 250 Ashkenazi Jewish parkinsonian individuals treated at a tertiary care center. We identified two individuals with N370S/R496H compound heterozygous mutations and two with N370S homozygous mutations; one individual died before completing detailed evaluation. TCS (n = 3) demonstrated nigral hyperechogenicity that was greater than controls [median area maximal substantia nigra echogenicity (aSNmax) = 0.28 cm(2) vs. 0.14 cm(2), P = 0.005], but similar to idiopathic PD (aSNmax = 0.31 cm(2)). FDG PET (n = 2) demonstrated hypermetabolism of the lentiform nuclei, and F-fluorodopa PET (n = 2), bilateral reduction in striatal F-dopa uptake. Olfaction was markedly impaired in the two tested cases, including onset of smell disturbance in adolescence in one. Neuropsychological features (n = 3) were consistent with Parkinson's disease (PD) or diffuse Lewy body disease (DLB). The imaging, neuropsychological and olfactory markers suggest the GD phenotype includes PD with and without features of DLB, marked olfactory loss, nigral hyperechogenicity on TCS, and F-dopa and FDG PET abnormalities., ((c) 2010 Movement Disorder Society.)

Background: While homozygous mutations in the PINK1 gene cause recessively inherited early-onset Parkinson disease (PD), heterozygous mutations have been suggested as a susceptibility factor., Methods: To evaluate this hypothesis, 4 homozygous PINK1 patients with PD and 10 asymptomatic carriers of a single heterozygous mutation from a large German family (family W) were included in this study. Clinical follow-up of the heterozygous mutation carriers 3 years after the initial visit included a detailed videotaped neurologic examination using the Unified Parkinson's Disease Rating Scale III protocol and smell and color discrimination testing. At follow-up, PET with 18-fluorodopa (FDOPA) of 13 family members was obtained in order to evaluate the clinical phenotype in light of nigostriatal dopaminergic functioning. The clinical and PET data were compared to those of healthy controls., Results: While there was mild worsening of clinical signs in previously affected heterozygous mutation carriers upon follow-up, 3 additional individuals had newly developed signs of possible PD. Hyposmia was found in 7 of the heterozygous mutation carriers, diminished color discrimination in 4. The homozygous mutation carriers who were all definitely affected with PD showed a severe, 60% decrease of caudate and putaminal FDOPA uptake; heterozygous offspring also had a significant 20% putaminal FDOPA uptake reduction compared to controls., Conclusions: Our findings strengthen the hypothesis that heterozygous PINK1 mutations act as a susceptibility factor to develop at least subtle Parkinson disease motor and nonmotor signs, as supported by the finding of a reduced striatal dopaminergic FDOPA uptake not only in homozygous but also, albeit to a lesser extent, in heterozygous mutation carriers.

The role of single heterozygous mutations in the putatively recessive Parkin gene in Parkinson disease (PD) is a vividly debated issue, partly caused by the largely unknown frequency of these mutations in healthy individuals. We investigated mutations in all 12 Parkin exons in 356 controls from two European populations including individuals from South Tyrol and Germany. None of the controls carried a homozygous or compound heterozygous mutation. Seventeen carriers of rare heterozygous alterations were detected, of which 13 (13/356; 3.7%) are considered to alter protein structure including four different gene dosage alterations, four missense mutations, and two frameshift mutations. Two of the mutations occurred recurrently in the South Tyrolean population. There was no obvious difference in the mutation frequency between the two populations. One of the presumably healthy mutation carrier was available for re-examination at the age of 67 years. He presented with mild signs of parkinsonism but not fulfilling diagnostic criteria for definite PD. To elucidate the role of heterozygosity is important for genetic testing and counseling of mutation carriers. A detailed clinical prospective and follow-up examination of mutation carriers is required for a better understanding of the role of heterozygous Parkin mutations.