Multiancestry analysis of the HLA locus in Alzheimer's and Parkinson's diseases uncovers a shared adaptive immune response mediated by HLA-DRB1*04 subtypes.

Across multiancestry groups, we analyzed Human Leukocyte Antigen (HLA) associations in over 176,000 individuals with Parkinson's disease (PD) and Alzheimer's disease (AD) versus controls. We demonstrate that the two diseases share the same protective association at the HLA locus. HLA-specific fine-mapping showed that hierarchical protective effects of HLA-DRB1*04 subtypes best accounted for the association, strongest with HLA-DRB1*04:04 and HLA-DRB1*04:07, and intermediary with HLA-DRB1*04:01 and HLA-DRB1*04:03. The same signal was associated with decreased neurofibrillary tangles in postmortem brains and was associated with reduced tau levels in cerebrospinal fluid and to a lower extent with increased Aß42. Protective HLA-DRB1*04 subtypes strongly bound the aggregation-prone tau PHF6 sequence, however only when acetylated at a lysine (K311), a common posttranslational modification central to tau aggregation. An HLA-DRB1*04-mediated adaptive immune response decreases PD and AD risks, potentially by acting against tau, offering the possibility of therapeutic avenues.

Comparative whole transcriptome analysis of Parkinson's disease focusing on the efficacy of zonisamide.

OBJECTIVE: Interindividual variations in responsiveness to zonisamide in patients with Parkinson's disease (PD) have been observed in clinical settings. To decipher the molecular mechanisms determining the efficacy of zonisamide, we conducted whole transcriptome sequencing analysis of patients with PD. METHODS: We selected 23 super-responders (SRs) and 25 non-responders (NRs) to zonisamide from patients with PD who had participated in a previous clinical trial for the approval of zonisamide for the treatment of 'wearing-off'. Whole transcriptome analysis of peripheral blood was conducted on samples taken before and 12 weeks after zonisamide treatment. We performed differential gene expression analysis to compare between the SRs and NRs at each time point. RESULTS: Differentially expressed genes in the pre-treatment samples were significantly enriched for glutamatergic synapses and insulin-like growth factor binding (Padj=7.8 × 10-3 and 0.029, respectively). The gene sets associated with these functions changed more dynamically by treatment in SRs than NRs (p=7.2 × 10-3 and 8.2 × 10-3, respectively). CONCLUSIONS: Our results suggest that the efficacy of zonisamide in PD patients is associated with glutamate-related synaptic modulation and p53-mediated dopaminergic neural loss. Their transcriptomic differences could be captured before treatment, which would lead to the realisation of future personalised treatment.

Trans-Ethnic Fine-Mapping of the Major Histocompatibility Complex Region Linked to Parkinson's Disease.

BACKGROUND: Despite evidence for the role of human leukocyte antigen (HLA) in the genetic predisposition to Parkinson's disease (PD), the complex haplotype structure and highly polymorphic feature of the major histocompatibility complex (MHC) region has hampered a unified insight on the genetic risk of PD. In addition, a majority of the reports focused on Europeans, lacking evidence on other populations. OBJECTIVES: The aim of this study is to elucidate the genetic features of the MHC region associated with PD risk in trans-ethnic cohorts. METHODS: We conducted trans-ethnic fine-mapping of the MHC region for European populations (14,650 cases and 1,288,625 controls) and East Asian populations (7712 cases and 27,372 controls). We adopted a hybrid fine-mapping approach including both HLA genotype imputation of genome-wide association study (GWAS) data and direct imputation of HLA variant risk from the GWAS summary statistics. RESULTS: Through trans-ethnic MHC fine-mapping, we identified the strongest associations at amino acid position 13 of HLA-DRß1 (P = 6.0 × 10-15 ), which explains the majority of the risk in HLA-DRB1. In silico prediction revealed that HLA-DRB1 alleles with histidine at amino acid position 13 (His13) had significantly weaker binding affinity to an α-synuclein epitope than other alleles (P = 9.6 × 10-4 ). Stepwise conditional analysis suggested additional independent associations at Ala69 in HLA-B (P = 1.0 × 10-7 ). A subanalysis in Europeans suggested additional independent associations at non-HLA genes in the class III MHC region (EHMT2; P = 2.5 × 10-7 ). CONCLUSIONS: Our study highlights the shared and distinct genetic features of the MHC region in patients with PD across ethnicities. © 2021 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Variants in saposin D domain of prosaposin gene linked to Parkinson's disease.

Recently, the genetic variability in lysosomal storage disorders has been implicated in the pathogenesis of Parkinson's disease. Here, we found that variants in prosaposin (PSAP), a rare causative gene of various types of lysosomal storage disorders, are linked to Parkinson's disease. Genetic mutation screening revealed three pathogenic mutations in the saposin D domain of PSAP from three families with autosomal dominant Parkinson's disease. Whole-exome sequencing revealed no other variants in previously identified Parkinson's disease-causing or lysosomal storage disorder-causing genes. A case-control association study found two variants in the intronic regions of the PSAP saposin D domain (rs4747203 and rs885828) in sporadic Parkinson's disease had significantly higher allele frequencies in a combined cohort of Japan and Taiwan. We found the abnormal accumulation of autophagic vacuoles, impaired autophagic flux, altered intracellular localization of prosaposin, and an aggregation of α-synuclein in patient-derived skin fibroblasts or induced pluripotent stem cell-derived dopaminergic neurons. In mice, a Psap saposin D mutation caused progressive motor decline and dopaminergic neurodegeneration. Our data provide novel genetic evidence for the involvement of the PSAP saposin D domain in Parkinson's disease.

In silico drug screening by using genome-wide association study data repurposed dabrafenib, an anti-melanoma drug, for Parkinson's disease.

Parkinson's disease (PD) is a neurodegenerative disorder characterized by dopaminergic neuron loss. At present, there are no drugs that stop the progression of PD. As with other multifactorial genetic disorders, genome-wide association studies (GWASs) found multiple risk loci for PD, although their clinical significance remains uncertain. Here, we report the identification of candidate drugs for PD by a method using GWAS data and in silico databases. We identified 57 Food and Drug Administration-approved drug families as candidate neuroprotective drugs for PD. Among them, dabrafenib, which is known as a B-Raf kinase inhibitor and is approved for the treatment of malignant melanoma, showed remarkable cytoprotective effects in neurotoxin-treated SH-SY5Y cells and mice. Dabrafenib was found to inhibit apoptosis, and to enhance the phosphorylation of extracellular signal-regulated kinase (ERK), and inhibit the phosphorylation of c-Jun NH2-terminal kinase. Dabrafenib targets B-Raf, and we confirmed a protein-protein interaction between B-Raf and Rit2, which is coded by RIT2, a PD risk gene in Asians and Caucasians. In RIT2-knockout cells, the phosphorylation of ERK was reduced, and dabrafenib treatment improved the ERK phosphorylation. These data indicated that dabrafenib exerts protective effects against neurotoxicity associated with PD. By using animal model, we confirmed the effectiveness of this in silico screening method. Furthermore, our results suggest that this in silico drug screening system is useful in not only neurodegenerative diseases but also other common diseases such as diabetes mellitus and hypertension.

Genome-wide association study identifies zonisamide responsive gene in Parkinson's disease patients.

Long-term treatment of Parkinson's disease (PD) by levodopa leads to motor complication "wearing-off". Zonisamide is a nondopaminergic antiparkinsonian drug that can improve "wearing-off" although response to the treatment varies between individuals. To clarify the genetic basis of zonisamide responsiveness, we conducted a genome-wide association study (GWAS) on 200 PD patients from a placebo-controlled clinical trial, including 67 responders whose "off" time decreased ≥1.5 h after 12 weeks of zonisamide treatment and 133 poor responders. We genotyped and evaluated the association between 611,492 single nucleotide polymorphisms (SNPs) and "off" time reduction. We also performed whole-genome imputation, gene- and pathway-based analyses of GWAS data. For promising SNPs, we examined single-tissue expression quantitative trait loci (eQTL) data in the GTEx database. SNP rs16854023 (Mouse double minute 4, MDM4) showed genome-wide significant association with reduced "off" time (PAdjusted = 4.85 × 10-9). Carriers of responsive genotype showed >7-fold decrease in mean "off" time compared to noncarriers (1.42 h vs 0.19 h; P = 2.71 × 10-7). In silico eQTL data indicated that zonisamide sensitivity is associated with higher MDM4 expression. Among the 37 pathways significantly influencing "off" time, calcium and glutamate signaling have also been associated with anti-epileptic effect of zonisamide. MDM4 encodes a negative regulator of p53. The association between improved motor fluctuation and MDM4 upregulation implies that p53 inhibition may prevent dopaminergic neuron loss and consequent motor symptoms. This is the first genome-wide pharmacogenetics study on antiparkinsonian drug. The findings provide a basis for improved management of "wearing-off" in PD by genotype-guided zonisamide treatment.

Bardet-Biedl syndrome and related disorders in Japan.

Bardet-Biedl syndrome (BBS) is a rare autosomal recessive disorder characterized by obesity, mental impairment, rod-cone dystrophy, polydactyly, male hypogonadism, and renal abnormalities. This disorder is caused by mutations in BBS1-21. Alström syndrome (AS), caused solely by mutations in ALMS1, is another genetic obesity syndrome clinically similar to BBS. We previously conducted the first nationwide survey of BBS in Japan and found four patients with genetically definite BBS. In this study, exome analyses were performed on new patients whose symptoms fulfilled the diagnostic criteria for BBS. We identified one reported heterozygous mutation in BBS1 (p.R429*) in one patient, two novel mutations (p.L493R and p.H719Y) in BBS20 in a second patient, and one novel mutation (p.Q920*) and one reported mutation (p.R2928*) in ALMS1 in a third patient, who was subsequently diagnosed with AS. The first patient with BBS was previously considered to have digenic heterozygous mutations in BBS1 and BBS4. RT-PCR and long-range genomic PCR analyses identified a new heterozygous mutation in BBS1, the deletion of exons 10 and 11. Thus, this patient was compound heterozygous for mutations in BBS1. Many studies have described digenic heterozygous mutations in BBS. However, undetected mutations might have existed in either one of the mutated genes.

Wide distribution of alpha-synuclein oligomers in multiple system atrophy brain detected by proximity ligation.

Multiple system atrophy (MSA) is a fatal adult-onset neurodegenerative disease that is characterized by varying degrees of cerebellar dysfunction and Parkinsonism. The neuropathological hallmark of MSA is alpha-synuclein (AS)-positive glial cytoplasmic inclusions (GCIs). Although severe neuronal loss (NL) is also observed in MSA, neuronal inclusions (NIs) are rare compared to GCIs, such that the pathological mechanism of NL in MSA is unclear. GCIs and NIs are late-stage pathology features relative to AS oligomers and may not represent early pathological changes in MSA. To reveal the early pathology of MSA, it is necessary to examine the early aggregation of AS, i.e., AS oligomers. Here, we adopted a proximity ligation assay (PLA) to examine the distribution of AS oligomers in brain tissue samples from patients with MSA and other diseases. Surprisingly, MSA brains showed a widespread distribution and abundant accumulation of oligomeric AS in neurons as well as oligodendrocytes of the neocortex. In several regions, oligomeric AS signal intensity was higher in cases with MSA than in cases with Parkinson's disease. In contrast to previous studies, AS-PLA revealed abundant AS oligomer accumulation in Purkinje cells in MSA brains, identifying oligomeric AS accumulation as a possible cause of Purkinje cell loss. This wide distribution of AS oligomers in MSA brain neurons has not been described previously and indicates a pathological mechanism of NL in MSA.

A novel PIGN mutation and prenatal diagnosis of inherited glycosylphosphatidylinositol deficiency.

Glycosylphosphatidylinositol (GPI) anchors tether proteins to the extracellular face of eukaryotic plasma membranes. Defects in the human GPI anchor biosynthetic pathway cause inherited GPI deficiencies (IGDs) characterized by multiple congenital anomalies: dysmorphic faces, developmental delay, hypotonia, and epilepsy. We report the case of a 6-year-old boy with severe psychomotor developmental delay, epilepsy, and decreased granulocyte surface expression of GPI-anchored protein that suggested autosomal recessive GPI deficiency. The case underwent target exome sequencing to screen for IGDs. Target exome sequencing of the proband identified an apparently homozygous c.808T > C (p.Ser270Pro) mutation in PIGN, a gene involved in the GPI anchor biosynthetic pathway. As his parents were expecting another child, genetic carrier screening was conducted for the parents. Direct sequencing of the parents identified a heterozygous c.808T > C PIGN mutation in the father but none in the mother. To identify the mother's mutation, we performed semi-quantitative real-time PCR of the PIGN exons and long PCR, identifying a microdeletion in PIGN (del exons 2-14). The proband had inherited this microdeletion from his mother. Prenatal diagnosis of the fetus revealed that it was a heterozygous carrier of the mother's pathogenic allele. Here, we report a sporadic case of inherited GPI deficiency with a PIGN mutation and the first case of prenatal diagnosis for GPI deficiency.

Comprehensive research synopsis and systematic meta-analyses in Parkinson's disease genetics: The PDGene database.

More than 800 published genetic association studies have implicated dozens of potential risk loci in Parkinson's disease (PD). To facilitate the interpretation of these findings, we have created a dedicated online resource, PDGene, that comprehensively collects and meta-analyzes all published studies in the field. A systematic literature screen of -27,000 articles yielded 828 eligible articles from which relevant data were extracted. In addition, individual-level data from three publicly available genome-wide association studies (GWAS) were obtained and subjected to genotype imputation and analysis. Overall, we performed meta-analyses on more than seven million polymorphisms originating either from GWAS datasets and/or from smaller scale PD association studies. Meta-analyses on 147 SNPs were supplemented by unpublished GWAS data from up to 16,452 PD cases and 48,810 controls. Eleven loci showed genome-wide significant (P < 5 × 10(-8)) association with disease risk: BST1, CCDC62/HIP1R, DGKQ/GAK, GBA, LRRK2, MAPT, MCCC1/LAMP3, PARK16, SNCA, STK39, and SYT11/RAB25. In addition, we identified novel evidence for genome-wide significant association with a polymorphism in ITGA8 (rs7077361, OR 0.88, P  =  1.3 × 10(-8)). All meta-analysis results are freely available on a dedicated online database (www.pdgene.org), which is cross-linked with a customized track on the UCSC Genome Browser. Our study provides an exhaustive and up-to-date summary of the status of PD genetics research that can be readily scaled to include the results of future large-scale genetics projects, including next-generation sequencing studies.

Extremely Longitudinally Extensive Transverse Myelitis in a Patient With Myelin Oligodendrocyte Glycoprotein Antibody-Associated Disease.

Longitudinally extensive myelitis with 15 or more vertebrae in length is extremely rare, with limited evidence regarding clinical features and therapeutic response. We report a case of a 29-year-old male patient with extremely longitudinally extensive myelitis ultimately diagnosed as myelin oligodendrocyte glycoprotein-associated disease (MOGAD). The patient presented with an acute onset of meningismus, limb weakness, sensory disturbance below the C5 level, ataxia, and urinary retention. T2-weighted imaging on MRI showed an extremely longitudinally extensive spinal cord lesion ranging from C2 to the medullary conus, together with a left pontine lesion. Positive anti-myelin oligodendrocyte glycoprotein antibodies were serologically detected, which led to the diagnosis of MOGAD. Intravenous methylprednisolone followed by 1 mg/kg oral prednisolone with taper resulted in complete symptomatic and radiological resolution. The striking complete resolution despite the symptomatic and radiological severity observed in this case has been described in a few previously reported MOGAD cases. Extremely longitudinally extensive myelitis with excellent therapeutic response may be a characteristic presentation of MOGAD.

Anti-neurofascin 155 Antibody-positive Neuropathy in a Human Immunodeficiency Virus-infected Patient.

Human immunodeficiency virus (HIV)-associated neuropathy is a common complication of HIV infection and has several clinical subtypes. HIV-associated chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is a demyelinating neuropathy whose clinical features are known to differ from those of CIDP in the HIV-uninfected population. We herein report a case of CIDP in an HIV-infected patient who was finally diagnosed with anti-neurofascin 155 (NF155) antibody-positive neuropathy. The clinical features, including clinical findings and therapeutic responses, were typical of paranodal antibody-mediated neuropathy. To our knowledge, this is the first case of anti-NF155 antibody-associated neuropathy in an HIV-infected patient.

A novel TBK1 loss-of-function variant associated with ALS and parkinsonism phenotypes.

Loss-of-function (LoF) variants in the TANK binding kinase 1 (TBK1) gene are implicated in the pathogenesis of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia. In this study, we present the first familial cases of ALS and parkinsonism associated with a novel TBK1 variant. We describe two siblings: one diagnosed with classical ALS and the other with a unique syndrome overlapping ALS and parkinsonism. Comprehensive clinical and imaging evaluations supported these diagnoses. Genetic analysis through whole-genome sequencing revealed a previously unknown heterozygous splice site variant in TBK1. Functional assessments demonstrated that this splice site variant leads to abnormal splicing and subsequent degradation of the mutated TBK1 allele by nonsense-mediated decay, confirming its pathogenic impact. Our findings suggest a broader involvement of TBK1 in neurodegenerative diseases and underscore the need for further research into TBK1's role, advocating for screening for TBK1 variants in similar familial cases.

SPTLC2 variants are associated with early-onset ALS and FTD due to aberrant sphingolipid synthesis.

OBJECTIVE: Amyotrophic lateral sclerosis (ALS) is a devastating, incurable neurodegenerative disease. A subset of ALS patients manifests with early-onset and complex clinical phenotypes. We aimed to elucidate the genetic basis of these cases to enhance our understanding of disease etiology and facilitate the development of targeted therapies. METHODS: Our research commenced with an in-depth genetic and biochemical investigation of two specific families, each with a member diagnosed with early-onset ALS (onset age of <40 years). This involved whole-exome sequencing, trio analysis, protein structure analysis, and sphingolipid measurements. Subsequently, we expanded our analysis to 62 probands with early-onset ALS and further included 440 patients with adult-onset ALS and 1163 healthy controls to assess the prevalence of identified genetic variants. RESULTS: We identified heterozygous variants in the serine palmitoyltransferase long chain base subunit 2 (SPTLC2) gene in patients with early-onset ALS. These variants, located in a region closely adjacent to ORMDL3, bear similarities to SPTLC1 variants previously implicated in early-onset ALS. Patients with ALS carrying these SPTLC2 variants displayed elevated plasma ceramide levels, indicative of increased serine palmitoyltransferase (SPT) activity leading to sphingolipid overproduction. INTERPRETATION: Our study revealed novel SPTLC2 variants in patients with early-onset ALS exhibiting frontotemporal dementia. The combination of genetic evidence and the observed elevation in plasma ceramide levels establishes a crucial link between dysregulated sphingolipid metabolism and ALS pathogenesis. These findings expand our understanding of ALS's genetic diversity and highlight the distinct roles of gene defects within SPT subunits in its development.

YY1 binds to α-synuclein 3'-flanking region SNP and stimulates antisense noncoding RNA expression.

α-synuclein (SNCA) is an established susceptibility gene for Parkinson's disease (PD), one of the most common human neurodegenerative disorders. Increased SNCA is considered to lead to PD and dementia with Lewy bodies. Four single-nucleotide polymorphisms (SNPs) in SNCA 3' region were prominently associated with PD among different ethnic groups. To examine how these SNPs influence disease susceptibility, we analyzed their potential effects on SNCA gene expression. We found that rs356219 showed allele-specific features. Gel shift assay using nuclear extracts from SH-SY5Y cells showed binding of one or more proteins to the protective allele, rs356219-A. We purified the rs356219-A-protein complex with DNA affinity beads and identified a bound protein using mass spectrometry. This protein, YY1 (Yin Yang 1), is an ubiquitous transcription factor with multiple functions. We next investigated SNCA expression change in SH-SY5Y cells by YY1 transfection. We also analyzed the expression of antisense noncoding RNA (ncRNA) RP11-115D19.1 in SNCA 3'-flanking region, because rs356219 is located in intron of RP11-115D19.1. Little change was observed in SNCA expression levels; however, RP11-115D19.1 expression was prominently stimulated by YY1. In autopsied cortices, positive correlation was observed among RP11-115D19.1, SNCA and YY1 expression levels, suggesting their functional interactions in vivo. Knockdown of RP11-115D19.1 increased SNCA expression significantly in SH-SY5Y cells, suggesting its repressive effect on SNCA expression. Our findings of the protective allele-specific YY1 and antisense ncRNA raised a novel possible mechanism to regulate SNCA expression.

A multi-centre clinico-genetic analysis of the VPS35 gene in Parkinson disease indicates reduced penetrance for disease-associated variants.

BACKGROUND: Two recent studies identified a mutation (p.Asp620Asn) in the vacuolar protein sorting 35 gene as a cause for an autosomal dominant form of Parkinson disease . Although additional missense variants were described, their pathogenic role yet remains inconclusive. METHODS AND RESULTS: We performed the largest multi-center study to ascertain the frequency and pathogenicity of the reported vacuolar protein sorting 35 gene variants in more than 15,000 individuals worldwide. p.Asp620Asn was detected in 5 familial and 2 sporadic PD cases and not in healthy controls, p.Leu774Met in 6 cases and 1 control, p.Gly51Ser in 3 cases and 2 controls. Overall analyses did not reveal any significant increased risk for p.Leu774Met and p.Gly51Ser in our cohort. CONCLUSIONS: Our study apart from identifying the p.Asp620Asn variant in familial cases also identified it in idiopathic Parkinson disease cases, and thus provides genetic evidence for a role of p.Asp620Asn in Parkinson disease in different populations worldwide.

TUBB3 E410K Syndrome With Childhood-Onset Nonalcoholic Steatohepatitis.

CONTEXT: Nonalcoholic fatty liver disease (NAFLD) is becoming a major issue worldwide, even in children. Multiple parallel hits hypothesis has been suggested as progress of NAFLD, but the mechanism of NAFLD is not completely understood. ß-Tubulin is essential in mitoses, neuronal migration, and axon guidance during neuronal development. Pathogenic variants in the TUBB3 gene were shown to be associated with a wide spectrum of neurological abnormalities, but not accompanied by hepatic complications, such as NAFLD. OBJECTIVE: This work aims to examine the association between TUBB3 mutation and nonalcoholic steatohepatitis (NASH). METHODS: An 11-year-old girl has been followed up as having atypical Möbius syndrome since infancy, as she was born with bilateral ptosis, paralytic strabismus, and facial weakness. At age 7 years, she was diagnosed with TUBB3 E410K syndrome by whole-exome sequencing. At age 10 years, her blood examination revealed elevated liver transaminase levels, which persisted for almost 2 years. She underwent liver biopsy, the results of which were suggestive of NASH. RESULTS: The expression of TUBB3 was absent, but that of tyrosine hydroxylase (TH) was present in the parenchymal nerve fibers of the liver. On the other hand, in comparison with an autopsy case of NASH and a normal control, these showed coexpression of TUBB3 and TH in the liver. CONCLUSION: We report the first case of TUBB3 E410K syndrome accompanied by NASH. This case suggests that the TUBB3 mutation may be associated with the pathogenesis and progression of NASH in humans.

Long-Surviving Adult Siblings With Joubert Syndrome Harboring a Novel Compound Heterozygous CPLANE1 Variant.

Background and Objectives: We describe 2 long-surviving siblings with a mild phenotype of Joubert syndrome (JBTS) harboring a novel compound heterozygous missense variant in the CPLANE1 gene. Methods: Targeted sequencing data of 2 middle-aged siblings (sister and brother) with JBTS were analyzed. Results: The patients were older than 60 years and presented with an inborn facial anomaly and ataxia, accompanied by a molar tooth sign on brain MRI. The male patient showed mild intellectual disability, abnormal eye movements, and progressive gait disturbance. Targeted sequencing revealed a compound heterozygous missense variant of CPLANE1 p.Arg1193Cys_Gln1223Pro; c.3577C>T_3668A>C. Multiple in silico assays predicted that the missense sites were pathogenic. Discussion: The phenotype-genotype correlation of CPLANE1 remains controversial, although many cases have been previously reported in children and young adults. Our study revealed a novel pathogenic variant of CPLANE1 in patients, confirming the role of this gene in JBTS, thus providing an opportunity for neurologists to recognize JBTS as a differential diagnosis for chronic progressive ataxia in an aging society.

Genetic and clinical analysis in a Chinese parkinsonism-predominant spinocerebellar ataxia type 2 family.

Parkinson's disease is a degenerative central nervous system disorder that often impairs motor skills, speech and other functions. We discovered a large Chinese family showing primarily parkinsonism symptoms with autosomal dominant inheritance. Six affected individuals in the family showed typical parkinsonism symptoms, including pill-rolling tremor. Two other affected individuals showed cerebellar ataxia symptoms. A whole-genome scan using the 50K single nucleotide polymorphism array with three different linkage methods detected two positive regions on chromosome 12q24.1 and 5q13.3. The ATXN2 gene, responsible for spinocerebellar ataxia type 2 (SCA2) was located precisely in the center of the positive region on chromosome 12. Further analysis of SCA2 revealed heterozygous pathological CAG expansions in the family. The affected individuals' symptoms were typical of parkinsonism, but complex. Inverse correlation between CAG repeat size and age of onset is not obvious in this pedigree. This parkinsonism-predominant SCA2 family shared the same disease gene locus with other 'standard' SCA2 families, but it is possible that variations in one or more modifier genes might account for the parkinsonism-predominant SCA2 predisposition observed in this pedigree.