Hon-Chung Fung

Multicenter Analysis of Glucocerebrosidase Mutations in Parkinson's Disease

BACKGROUNDnRecent studies indicate an increased frequency of mutations in the gene encoding glucocerebrosidase (GBA), a deficiency of which causes Gauchers disease, among patients with Parkinsons disease. We aimed to ascertain the frequency of GBA mutations in an ethnically diverse group of patients with Parkinsons disease.nnnMETHODSnSixteen centers participated in our international, collaborative study: five from the Americas, six from Europe, two from Israel, and three from Asia. Each center genotyped a standard DNA panel to permit comparison of the genotyping results across centers. Genotypes and phenotypic data from a total of 5691 patients with Parkinsons disease (780 Ashkenazi Jews) and 4898 controls (387 Ashkenazi Jews) were analyzed, with multivariate logistic-regression models and the Mantel-Haenszel procedure used to estimate odds ratios across centers.nnnRESULTSnAll 16 centers could detect two GBA mutations, L444P and N370S. Among Ashkenazi Jewish subjects, either mutation was found in 15% of patients and 3% of controls, and among non-Ashkenazi Jewish subjects, either mutation was found in 3% of patients and less than 1% of controls. GBA was fully sequenced for 1883 non-Ashkenazi Jewish patients, and mutations were identified in 7%, showing that limited mutation screening can miss half the mutant alleles. The odds ratio for any GBA mutation in patients versus controls was 5.43 across centers. As compared with patients who did not carry a GBA mutation, those with a GBA mutation presented earlier with the disease, were more likely to have affected relatives, and were more likely to have atypical clinical manifestations.nnnCONCLUSIONSnData collected from 16 centers demonstrate that there is a strong association between GBA mutations and Parkinsons disease.

Genome-wide genotyping in Parkinson's disease and neurologically normal controls: first stage analysis and public release of data

BACKGROUNDnSeveral genes underlying rare monogenic forms of Parkinsons disease have been identified over the past decade. Despite evidence for a role for genetics in sporadic Parkinsons disease, few common genetic variants have been unequivocally linked to this disorder. We sought to identify any common genetic variability exerting a large effect in risk for Parkinsons disease in a population cohort and to produce publicly available genome-wide genotype data that can be openly mined by interested researchers and readily augmented by genotyping of additional repository subjects.nnnMETHODSnWe did genome-wide, single-nucleotide-polymorphism (SNP) genotyping of publicly available samples from a cohort of Parkinsons disease patients (n=267) and neurologically normal controls (n=270). More than 408,000 unique SNPs were used from the Illumina Infinium I and HumanHap300 assays.nnnFINDINGSnWe have produced around 220 million genotypes in 537 participants. This raw genotype data has been and as such is the first publicly accessible high-density SNP data outside of the International HapMap Project. We also provide here the results of genotype and allele association tests.nnnINTERPRETATIONnWe generated publicly available genotype data for Parkinsons disease patients and controls so that these data can be mined and augmented by other researchers to identify common genetic variability that results in minor and moderate risk for disease.

A common genetic factor for Parkinson disease in ethnic Chinese population in Taiwan

BackgroundParkinsons disease (PD) is the most common neurodegenerative movement disorder, characterized clinically by resting tremor, bradykinesia, postural instability and rigidity. The prevalence of PD is approximately 2% of the population over 65 years of age and 1.7 million PD patients (age ≥ 55 years) live in China. Recently, a common LRRK2 variant Gly2385Arg was reported in ethnic Chinese PD population in Taiwan. We analyzed the frequency of this variant in our independent PD case-control population of Han Chinese from Taiwan.Methods305 patients and 176 genetically unrelated healthy controls were examined by neurologists and the diagnosis of PD was based on the published criteria. The region of interest was amplified with standard polymerase chain reaction (PCR). PCR fragments then were directly sequenced in both forward and reverse directions. Differences in genotype frequencies between groups were assessed by the X2 test, while X2 analysis was used to test for the Hardy-Weinberg equilibrium.ResultsOf the 305 patients screened we identified 27 (9%) with heterozygous G2385R variant. This mutation was only found in 1 (0.5%) in our healthy control samples (odds ratio = 16.99, 95% CI: 2.29 to 126.21, p = 0.0002). Sequencing of the entire open reading frame of LRRK2 in G2385R carriers revealed no other variants.ConclusionThese data suggest that the G2385R variant contributes significantly to the etiology of PD in ethnic Han Chinese individuals. With consideration of the enormous and expanding aging Chinese population in mainland China and in Taiwan, this variant is probably the most common known genetic factor for PD worldwide.

Evidence suggesting that Homo neanderthalensis contributed the H2 MAPT haplotype to Homo sapiens.

The tau (MAPT) locus exists as two distinct clades, H1 and H2. The H1 clade has a normal linkage disequilibrium structure and is the only haplotype found in all populations except those derived from Caucasians. The H2 haplotype is the minor haplotype in Caucasian populations and is not found in other populations. It shows no recombination over a region of 2 Mb with the more common H1 haplotype. The distribution of the haplotype and analysis of the slippage of dinucleotide repeat markers within the haplotype suggest that it entered Homo sapiens populations between approx. 10000 and 30000 years ago. However, sequence comparison of the H2 haplotype with the H1 haplotype and with the chimp sequence suggests that the common founder of the H1 and H2 haplotypes was far earlier than this. We suggest that the H2 haplotype is derived from Homo neanderthalensis and entered H. sapiens populations during the co-existence of these species in Europe from approx. 45000 to 18000 years ago and that the H2 haplotype has been under selection pressure since that time, possibly because of the role of this H1 haplotype in neurodegenerative disease.

Conflicting Results Regarding the Semaphorin Gene (SEMA5A) and the Risk for Parkinson Disease

To the Editor: n nThe strongest variant (rs7702187) associated with Parkinson disease (PD [MIM 168600]) reported in the whole-genome association study by Maraganore et al.1 was evaluated in two independent case-control series of patients from Finland and Taiwan, as were four other variants located within SEMA5A (MIM 609297). The Finnish series comprised 146 patients with sporadic PD (mean age 67.2 years, range 38–88 years; 41% women) and 135 neurologically normal, healthy control subjects (mean age 65.8 years, range 37–80 years; 64% women). All individuals were recruited from the neurological outpatient clinics of the Helsinki University Central Hospital and Seinajoki Central Hospital. The Taiwanese series consisted of 303 patients with sporadic PD (mean age 61.9 years, range 24–91 years; 46.2% women) and 171 control individuals (mean age 60.1 years, range 31–86 years; 43.9% women). Patients were selected from the neurological clinic of Chang-Gung Memorial Hospital. Individuals with evidence of secondary parkinsonism or with atypical features such as early dementia, ophthalmoplegia, early autonomic failure, and pyramidal signs were not included in this study. All patients included in the study fulfilled PD diagnosis criteria.2 All participants signed an informed consent form. n nTaqman Assays-by-Design SNP Genotyping Assays (Applied Biosystems) were employed for allelic discrimination of all SNPs. Differences in allele and genotype distributions were analyzed using the χ2 test, and two-tailed P values are presented. Haplotype frequency comparisons between cases and controls were performed with PHASE version 2.1 software.3 One thousand permutations were performed for each comparison. The COCAPHASE module of the UNPHASED statistical package was used for linkage-disequilibrium (LD) analyses.4 Power calculations were performed with PS version 2.1.30.5 n nAllele and genotype frequency information for each of the markers is shown in table 1. None of the markers showed any significant association with disease in the Finnish series. However, we were able to replicate the reported association with marker rs7702187 in the Taiwanese cohort (odds ratio [OR] = 1.53, 95% CI 1.12–2.10, P=.007). Genotype analysis showed that individuals homozygous for the A allele had a significantly decreased risk of PD compared with those heterozygous or homozygous for the T allele (OR = 0.60, 95% CI 0.41–0.88, P=.009). A significant association was also found for the rs3798097 marker, which is located in the 5′ UTR region of SEMA5A (OR for the C allele was 1.71, 95% CI 1.06–2.73, P=.025). n n n nTableu20021 n nGenotype and Allele Frequency Distribution of the Polymorphisms Analyzed across SEMA5A on Chromosome 5 n n n nBoth populations showed a complete lack of LD for any pairs of neighboring polymorphisms (all D′ values were <0.5, independently of diagnostic group). Haplotype frequency comparisons did not reveal any significant differences between patients and controls in the Finnish series (P=.901) or between patients and controls in the Taiwanese series (P=.091) (table 2). n n n nTableu20022 n nHaplotype Frequency Distribution in Finnish and Taiwanese Series[Note] n n n nThe present results point to differential risk effects of SEMA5A marker alleles across populations. In the Taiwanese population, we have found an associated risk in the same locus as the one reported elsewhere1 but in an opposite direction. That is, the at-risk allele that we report was found to be protective in the sample from Minnesota described by Maraganore et al.1 This could be due to the effect of LD between this polymorphism and another “true” risk variant within the gene. The lack of association shown in the Finnish population could be related to genetic heterogeneity, or, alternatively, the Finnish series might not be large enough to assess genes with modest effects (this sample has a 60% power to detect risks of 1.7, at α=0.05). n nThe replication of an association with SEMA5A in a Taiwanese population makes it a good candidate for further analyses in different populations.

Lack of G2019S LRRK2 mutation in a cohort of taiwanese with sporadic parkinson's disease

Mutations in the leucine‐rich repeat kinase 2 (LRRK2) gene have been shown to cause autosomal dominant and sporadic Parkinsons disease (PD). We report here the frequency of a common heterozygous mutation, 2877510G>A, which produces a glycine‐to‐serine amino acid substitution at codon 2019 in idiopathic Taiwanese PD. The extreme rarity of the G2019S mutation in our population suggests the occurrence of this mutation resulted from a common European founder.

Association of Tau Haplotype-Tagging Polymorphisms with Parkinson’s Disease in Diverse Ethnic Parkinson’s Disease Cohorts

Background: The overlap in the clinical and pathological features of tauopathies and synucleinopathies raises the possibility that the tau protein may be important in Parkinson’s disease (PD) pathogenesis. Several MAPT polymorphisms that define the tau H1 haplotype have been investigated for an association with PD with conflicting results; however, two meta-analyses support an association between haplotype H1 and PD. Methods: In this study, we recruited 508 patients and 611 healthy controls from Greek, Finnish and Taiwanese populations. We examined the possible genetic role of variation within MAPT in PD using haplotype-tagging single polymorphisms (SNPs) in these ethnically different PD populations. Results: We identified a moderate association at SNP rs3785883 in the Greek cohort for both allele and genotype frequency (p = 0.01, p = 0.05, respectively) as well as for SNP rs7521 (genotype p = 0.02) and rs242557 (p = 0.01 genotypic, p = 0.04 allelic) in the Finnish population. There were no significant differences in genotype or allele distribution between cases and controls in the Taiwanese cohort. Conclusion: We failed to demonstrate a consistent association between the MAPT H1 haplotype (delineated by intron 9 ins/del) and PD in three ethnically diverse populations. However, the data presented here suggest that subhaplotypes of haplotype H1 may confer susceptibility to PD, and that either allelic heterogeneity or different haplotype composition explain the divergent haplotype results.

Analysis of the PINK1 gene in a cohort of patients with sporadic early-onset parkinsonism in Taiwan

Mutations in the PINK1 gene have been shown to cause autosomal recessive Parkinsons disease (PD) and/or early onset sporadic PD in Italy, Spain, North America, Ireland, and Asia. However, there are limited data on PINK1 mutations in sporadic early onset Asian PD patients. To determine the prevalence of PINK1 mutation in Taiwanese population, we conducted genetic analysis of PINK1 mutation in 73 early onset sporadic PD and 94 normal control subjects. We only identified a novel single heterozygous mutation R 407Q mutation in exon 6 of this gene in one patient at the age onset of 54. Overall, these data indicate that PINK1 mutations are rare in our population. Based on our results, unless common mutational hotspots are identified, routine testing for this mutation at least in our population may not be cost-effective.

Epileptic seizures in neurofibromatosis type 1 are related to intracranial tumors but not to neurofibromatosis bright objects

OBJECTIVEnTo investigate the relationship between intracranial lesions and epileptic seizures in neurofibromatosis type 1 (NF1) patients.nnnBACKGROUNDnNF1 is one of the most common autosomal dominant neurocutaneous disorders, and epilepsy is more prevalent in NF1 patients than in the general population. Epileptic seizures were found to be related to various types of intracranial lesions in NF1 patients.nnnMETHODSnThe clinical characteristics of NF1 (1986-2006 in Chung-Gung Memorial Hospital), diagnosed on the basis of the criteria of the National Institutes of Health Consensus Conference (1988), were reviewed by 2 neurologists. We diagnosed epileptic seizures of NF1 patients on the basis of clinical appearances and a history of antiepileptic drugs. Magnetic resonance images were also evaluated by 2 neuroradiologists to confirm the locations of brain tumors or neurofibromatosis bright objects (NBOs). The locations of NBOs were classified into 4 categories: cortex and hippocampus, subcortical white matter, basal ganglia, and infratentorial area. The association between the location of the lesions and the occurrence of seizure in NF1 patients was analyzed statistically.nnnRESULTSnThe medical records of 630 NF1 patients were reviewed. In this cohort, 37 (5.87%) NF1 patients had epileptic seizures. The patients include 22 males (59.5%) and 15 females (40.5%). The mean seizure onset age was 14.8 years (2 months to 72 years). The most common seizure pattern was partial onset seizures, 3 simple partial seizures, and 14 complex partial seizures. Other seizure types found include 15 primary generalized seizures (2 absence seizures and 13 generalized tonic-clonic seizures), 2 infantile spasms, and 3 unclassified. A total of 172 (23 with epilepsy and 149 without epilepsy) NF1 patients underwent MRI examinations. NBOs were identified in 16 (69.6%) epilepsy patients and in 108 (72.5%) patients without epilepsy. The location or the number of these intracranial lesions does not show significant correlation with the occurrence of epilepsy in our cohort. Among 11 NF1 patients with intracranial tumors, 4 patients had seizures (36.36%), vs. 19 out of 161 NF1 patients (11.80%) without tumors.nnnCONCLUSIONnThe occurrence of epileptic seizures in NF1 patients is related to intracranial tumors but not to NBOs.

Promoter polymorphisms modulating HSPA5 expression may increase susceptibility to Taiwanese Alzheimer's disease.

Endoplasmic reticulum (ER) chaperone heat shock 70xa0kDa protein 5 (HSPA5/GRP78) is known to be involved in the metabolism of amyloid precursor protein and neuronal death in Alzheimer’s disease (AD) could arise from dysfunction of the ER. Through a case–control study and an expression assay, we investigated the association of HSPA5 −415 G/A (rs391957), −370 C/T (rs17840761) and −180 del/G (rs3216733) polymorphisms with Taiwanese AD. The overall genotype and allele frequency distribution at the completely linked −415 G/A and −180 del/G sites showed significant difference between AD cases and controls (Pxa0=xa00.020 and 0.009, respectively). A decrease in risk of developing AD was demonstrated for −415 AA/−180 GG genotype [ORxa0=xa00.38, 95% confidence interval (CI)xa0=xa00.18–0.75, Pxa0=xa00.007] and −415 A/−180 G allele (ORxa0=xa00.69, 95% CIxa0=xa00.51–0.91, Pxa0=xa00.009). The HSPA5 transcriptional activity of the −415 A/−180 G allele was significantly lower than that of the −415 G/−180 del alleles, whereas induction of HSPA5 expression after ER stress was markedly increased in the cells with the −415 A/−180 G allele. Therefore, our preliminary results may suggest a protective role of the HSPA5 −415 A/−180 G allele in Taiwanese AD susceptibility.