[Correlation study of semaphorin 5a with risk of Parkinson's disease in a Chinese Han population]

OBJECTIVE

To investigate the relationship of Semaphorin 5A (SEMA5A) and risk of Parkinson's disease (PD).

METHODS

Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) assay was used to check two single nucleotide polymorphisms (SNPs) within SEMA5A in 244 PD patients and 174 healthy control subjects of Chinese Han ancestry. And the results were verified by gene sequencing.

RESULTS

The SEMA5A variant genotype (allele) of rs7702187 and rs3798097 had no correlation with the risk of PD in the samples (rs7702187: OR(genotype AT) 0.95, 95% CI 0.61-1.48, OR (genotype AA) = 1.84, 95% CI 0.85-3.99, OR(genotype AT + AA) = 1.21, 95% CI 0.82-1.77, P > 0.05; rs3798097: OR(genotype CT) = 1.06, 95% CI 0.62-1.79, OR(genotype TT) = 0.72, 95% CI 0.10-5.18, OR(genotype CT + T) = 1.01, 95% CI 0.62-1.67, P > 0.05). Comparing with the most common haplotype TC, neither AC haplotype nor TT haplotype showed any correlation with risk of PD (OR = 1.19, 95% CI 0.84-1.69 for AC haplotype P > 0.05; OR = 0.99, 95% CI 0.59-1.70 for TT haplotype, P > 0.05).

CONCLUSION

SEMA5A is not implicated in PD risk in a Chinese Han population.

Minority enrollment in Parkinson's disease clinical trials

Under-representation of minorities in clinical trials limits access to information relevant to all segments of the population. We assessed the enrollment of minority subjects with Parkinson's disease (PD) into clinical trials. We searched PubMed for published studies of PD trials conducted in the US over the past 20 years and found that only 41 reported racial/ethnic participation (17%). In those trials reporting race/ethnicity, 8% of subjects were non-white, compared to 20% of the non-white US population over age 60. Results of this study identified the need for better reporting of racial composition in clinical trials and for the enrollment of more minority participants in research studies.

Disparities of care in veterans with Parkinson's disease

BACKGROUND

Disparities of Parkinson's disease (PD) care have not been assessed.

METHODS

We examined the medical records of 309 (83%) non-Hispanic White and 65 (17%) non-White Los Angeles veterans with PD from 1998 to 2004 to determine if care quality as measured by 10 PD indicators different by race/ethnicity.

RESULTS

In multivariate modeling, adherence to indicators was higher among non-Hispanic Whites (71% vs. 65%, risk ratio 1.15, 95% CI [1.07-1.32]) compared to non-Whites. Differences in adherence by race/ethnicity were greatest for depression treatment (p<0.05).

CONCLUSIONS

We detected disparities in quality of PD care, particularly in depression treatment. Future research should determine causes for these so that interventions can be designed to reduce such disparities.

Midbrain transcranial sonography in Korean patients with Parkinson's disease

Transcranial sonography (TCS) is potentially useful for the diagnosis of Parkinson's disease (PD). However, studies on TCS have so far been restricted to European populations. To investigate the efficacy of TCS in Korean PD patients and its correlation with the clinical features, we carried out midbrain TCS in 43 PD patients and 35 normal controls and evaluated the area of the substantia nigra (SN) hyperechogenicity and its ratio to the area of the whole midbrain. In 16 subjects (21%), TCS was unsuccessful due to insufficient acoustic temporal bone windows. The mean area of bilateral SN hyperechogenicity and its ratio to the midbrain area were greater in the PD patients than that in the controls (P < 0.01). In the PD patients, the area of SN hyperechogenicity and its ratio to the individual midbrain area were moderately correlated with the PD duration (r = 0.526 and 0.536, P = 0.01, respectively) but not with the age, UPDRS motor scores or H-Y stage. There was no difference in the SN hyperechogenicity between the tremor-dominant, akinetic-rigid, and mixed-type PD patients. In conclusion, midbrain TCS is an effective diagnostic tool for detecting PD in the Korean population. However, it does not reflect the severity or phenotypes of parkinsonism.

Mutations in the glucocerebrosidase gene are associated with early-onset Parkinson disease

OBJECTIVE

To evaluate the frequency of glucocerebrosidase (GBA) mutations in cases and controls enrolled in the Genetic Epidemiology of Parkinson's Disease (GEPD) study.

METHODS

We sequenced all exons of the GBA gene in 278 Parkinson disease (PD) cases and 179 controls enrolled in GEPD, with a wide range of age at onset (AAO), and that included a subset of 178 Jewish cases and 85 Jewish controls. Cases and controls were recruited without knowledge of family history of PD, and cases were oversampled in the AAO < 50 years category.

RESULTS

13.7% of PD cases (38/278) carried GBA mutations, compared with 4.5% of controls (8/179) (odds ratio [OR] 3.4, 95% CI 1.5 to 7.4). The frequency of GBA mutations was 22.2% in 90 cases with AAO < or = 50 years, compared with 9.7% in 185 cases with AAO > 50 years (OR 2.7, 95% CI 1.3 to 5.3). Adjusting for age at the time of evaluation, sex, family history of PD, and Jewish ancestry, GBA carriers had a 1.7-year-earlier AAO of PD (95% CI 0.5 to 3.3, p < 0.04) than noncarriers. The average AAO of PD was 2.5 years earlier in carriers with an AAO < or = 50 years compared with noncarriers (95% CI 0.6 to 4.5, p < 0.01) and this was not seen in the AAO > 50 years group. The frequency of GBA mutations was higher in a subset of 178 cases that reported four Jewish grandparents (16.9%) than in cases who did not report Jewish ancestry (8.0%) (p < 0.01). Nine different GBA mutations were identified in PD cases, including 84insGG, E326K, T369M, N370S, D409H, R496H, L444P, RecNciI, and a novel mutation, P175P.

CONCLUSIONS

This study suggests that the Glucocerebrosidase gene may be a susceptibility gene for Parkinson disease and that Glucocerebrosidase mutations may modify age at onset.

Glucocerebrosidase gene mutation is a risk factor for early onset of Parkinson disease among Taiwanese

BACKGROUND

Mutations in the glucocerebrosidase (GBA) gene have recently been identified as contributing to the development of Parkinson disease (PD) in Ashkenazi Jews.

METHODS

To investigate whether this finding can be confirmed in a Taiwanese population, we conducted a case control study in a cohort of 518 PD patients and 339 controls for the three common GBA mutations in Taiwan, L444P, RecNciI and R120W, using PCR restriction enzyme assay and DNA sequencing.

RESULTS

Heterozygous GBA mutations were detected in 16 PD patients (3.1%) and four controls (1.2%). Although this difference was not statistically significant (p = 0.0703), the average age at disease onset of the 16 PD patients (50.6 (12.3) years) was significantly younger than that of the total patient group (63.8 (10.5) years; p = 0.0007) and the non-carrier patient group (64.2 (10.2) years; p = 0.0005). After stratification by age, the frequency of mutation carriers was significantly higher for the early onset PD (EOPD, age at onset < or = 50 years) group than for age matched controls (12.9% vs 1.8%; p = 0.0335) and there was a trend towards an increased risk of the mutation carrier with EOPD (odds ratio 8.30; 95% CI 1.45 to 156.53). Clinically, all 16 patients carrying a GBA mutation presented with a typical parkinsonian phenotype and experienced a good or excellent response to levodopa.

CONCLUSIONS

Mutations of the GBA gene may be associated with the development of EOPD in Taiwan.

Role of ethnicity on the association of MAPT H1 haplotypes and subhaplotypes in Parkinson's disease

An association of the H1 haplotype and subhaplotypes in the microtubule-associated protein Tau (MAPT) gene with Parkinson's disease (PD) has been reported. To further evaluate their role in PD, we genotyped a sample set of 765 cases and controls consisting of two large European subgroups of German (n=418) and Serbian (n=347) origin for the MAPT haplotypes H1 and H2. The H1/H1 carriers were tested for three additional MAPT polymorphisms. In the Serbian sample, there was significant evidence (P=0.0108) of an association of the H1/H1 genotype and PD. Surprisingly, in the German sample, we did not find significant differences in genotype or haplotype frequencies between patients and controls. These results suggest that the role of H1 haplotypes in the etiology of PD may be ethnically dependent.

Pooled Analysis of Tobacco Use and Risk of Parkinson Disease

CONTEXT

Epidemiologic studies have reported that cigarette smoking is inversely associated with Parkinson disease (PD). However, questions remain regarding the effect of age at smoking onset, time since quitting, and race/ethnicity that have not been addressed due to sample size constraints. This comprehensive assessment of the apparent reduced risk of PD associated with smoking may provide important leads for treatment and prevention.

OBJECTIVE

To determine whether race/ethnicity, sex, education, age at diagnosis, and type of tobacco modify the observed effects of smoking on PD.

DESIGN, SETTING, AND PARTICIPANTS

We conducted the first ever pooled analysis of PD combining individual-level data from 8 US case-control and 3 cohort studies (Nurses' Health Study, Health Professionals Follow-Up Study, and Honolulu-Asia Aging Study) conducted between 1960 and 2004. Case-control studies provided data for 2328 PD cases and 4113 controls matched by age, sex, and ethnicity; cohort studies contributed 488 cases and 4880 controls selected from age- and sex-matched risk sets.

MAIN OUTCOME MEASURE

Incident PD.

RESULTS

We confirmed inverse associations between PD and smoking and found these to be generally stronger in current compared with former smokers; the associations were stronger in cohort than in case-control studies. We observed inverse trends with pack-years smoked at every age at onset except the very elderly (>75 years of age), and the reduction of risk lessened with years since quitting smoking. The risk reductions we observed for white and Asian patients were not seen in Hispanic and African American patients. We also found an inverse association both for smoking cigars and/or pipes and for chewing tobacco in male subjects.

CONCLUSIONS

Our data support a dose-dependent reduction of PD risk associated with cigarette smoking and potentially with other types of tobacco use. Importantly, effects seemed not to be influenced by sex or education. Differences observed by race and age at diagnosis warrant further study.

ELAVL4, PARK10, and the Celts

Genetic variability in ELAVL4 located in the PARK10 locus was recently associated with age-at-onset (AAO) in a series of Parkinson's disease (PD) patients originating from the United States. We examined five markers spanning ELAVL4 in Norwegian, United States, and Irish PD case-control samples. No association was found between the examined markers and AAO or PD in Norwegian or US samples. However, ELAVL4 markers (rs967582 and rs3902720) were significantly associated with susceptibility to PD in our Irish series. Our data suggest that the association between ELAVL4 and PD previously observed might be explained by a Celtic-founder effect.

Glucocerebrosidase mutations in Chinese subjects from Taiwan with sporadic Parkinson disease

BACKGROUND

An association between glucocerebrosidase, the enzyme deficient in Gaucher disease, and the synucleinopathies has been suggested both by the development of parkinsonism in Gaucher probands and carriers, as well as by the presence of mutations in the gene for glucocerebrosidase (GBA) in different series of subjects with synucleinopathies. In this study, an open access Parkinson repository was used to establish the incidence of GBA alterations in a different ethnic cohort with sporadic Parkinson disease (PD).

METHODS

The glucocerebrosidase gene was sequenced in samples collected from 92 Chinese Parkinson disease patients from Taiwan along with 92 clinically screened controls, matched for age and ethnicity.

FINDINGS

The frequency of GBA mutations among the Chinese PD probands was 4.3%, in contrast to 1.1% in Chinese controls. Mutant alleles identified included two known mutations, L444P and D409H, and two novel mutations, L174P and Q497R.

INTERPRETATION

These results, ascertained in subjects from Taiwan collected in a standardized and clinically rigorous open access Parkinson disease repository and screened by direct sequencing of GBA, demonstrate that GBA mutations are also encountered in Chinese subjects with sporadic PD at a higher frequency than many other known PD genes. The study demonstrates that the association of GBA mutations with the development of parkinsonian pathology is not related to ethnic origin.

Genetic analysis of LRRK2 P755L variant in Caucasian patients with Parkinson's disease

Parkinson's disease (PD) is the second most common neurodegenerative disease with major clinical features of bradykinesia, rigidity, resting tremor, and postural instability. Mutations in the leucine-rich repeat kinase 2 gene (LRRK2) have been identified both in familial and sporadic cases of PD. Recently, a P755L variant in the LRRK2 gene has been found to be responsible for 2% of Chinese patients with sporadic PD. To evaluate the frequency of the LRRK2 P755L variant in North American Caucasian patients with PD, we screened 426 PD patients and 37 additional patients with the combination of PD and essential tremor (ET) from our Parkinson Disease Center and Movement Clinic at Baylor College of Medicine. No P755L variant was found in our PD cohort. Therefore, we conclude that LRKK2 P755L variant is a rare cause of Caucasian PD and has no diagnostic utility in genetic testing of this population of patients.

LRRK2 and Parkinson?s disease in Norway

OBJECTIVES

Mutations in the LRRK2 gene have been associated with both familial and sporadic late-onset Parkinson's disease. A large number of mutations in this gene have been identified; however, for many of these variants, the pathogenicity and relative frequency are unknown. Herein, we investigate the frequency of a number of recently identified LRRK2 mutations in Norway.

METHODS

We genotyped eight putatively pathogenic LRRK2 mutations (R793M, R1067Q, I1371V, IVS31+3 A>G, M1869T, R1941H, T2356I and G2385R) in a series of 433 patients with Parkinson's disease and 587 controls from Norway. An intronic polymorphism previously reported to be associated with disease susceptibility was also examined (rs10506151).

RESULTS

The Lrrk2 R793M substitution was found in two healthy individuals. No other LRRK2 mutations were identified in the Norwegian population, and furthermore no association was observed between rs10506151 and Parkinson's disease (P = 0.41).

CONCLUSIONS

LRRK2 mutations other than the Lrrk2 G2019S mutation are rare in Norway. Our results indicate that the Lrrk2 R793M substitution is most likely a rare polymorphism.

Leucine-rich repeat kinase 2 G2385R variant is a risk factor for Parkinson disease in Asian population

To assess the effect of genetic factors on sporadic Parkinson disease, we performed a case-control study of a variant (G2385R) in Leucine-Rich Repeat kinase 2 among the Japanese population. The G2385R (c.7153G>A) variant was reported as a risk factor for sporadic Parkinson disease in the Chinese population from Taiwan and Singapore. Genotyping was conducted in 448 Parkinson disease patients and 457 healthy controls. The frequency of A allele in Parkinson disease was significantly higher than in the control (P=1.24x10(-4), odds ratio 2.63, 95% confidence interval 1.56-4.35). Our results suggest that the G2385R variant is a risk factor for sporadic Parkinson disease in the Asian population.

Independent occurrence of I2020T mutation in the kinase domain of the leucine rich repeat kinase 2 gene in Japanese and German Parkinson's disease families

To understand the genetic origin of I2020T mutation in the kinase domain of leucine rich repeat kinase 2 (LRRK2), we investigated the original PARK8 Japanese family (Sagamihara family) and a German family (family 32), both of which were found to harbor I2020T as the causal mutation for autosomal dominant familial Parkinson's disease (PD). Microsatellite-haplotype analysis around the LRRK2 gene indicated that the mutation-carrying haplotypes of the two families were distinct from each other. This indicated that the I2020T mutation, an essential pathogenic mutation of PARK8-related PD, had occurred independently in the two PD families.

Test-retest reliability of 24 hours of activity monitoring in individuals with Parkinson's disease in home and community

BACKGROUND/OBJECTIVE

This study examined the test-retest reliability of an activity monitor (AM) in home and community settings in individuals with Parkinson's disease (PD).

METHODS

Nine independent community dwellers with idiopathic PD were recruited (8 males and 1 female; median age = 66 years, range 46-71; Hoehn & Yahr score 2). Patients wore the AM for 3 separate sessions in the home and community with 7 days between each session. The first 2 sessions lasted 24 hours each, and the third session lasted 48 hours. Reliability indices and measures of variability were obtained by using intraclass correlation coefficients (ICC) and generalizability coefficients. The functional activity measures included the percentage of time spent in sleeping positions, sitting, standing, and walking; the number of transitions between sit and stand; the total number of transitions; the number of walking periods lasting 5 and 10 seconds; and stride frequency.

RESULTS

The ICCs for functional activities between the first and second consecutive days for the 48-hour session (third session) ranged from .76 to .92. The ICCs for the 7- and 14-day intervals ranged from .45 to .96, with walking-related measures showing the highest ICCs (range = .81 to .96). Across the three 24-hour periods (sessions 1 and 2, and the first 24 hours of session 3), the ICCs for walking-related measures were again high ranging from .87 to .92. Walking-related measures demonstrated the highest generalizability coefficients, indicating these measures have the highest test-retest reliability in comparison to other functional activity measures.

CONCLUSIONS

The present study shows that 24 hours of recording with an AM is a sufficient duration of time to reliably record patients' functional activity in the home and community settings. In addition, the highest test-retest reliability for activities across 7- and 14-day intervals were found for walking-related measures in individuals with PD, indicating these measures have the highest stability compared to the other measures of functional activity.

Association of GST M1 null polymorphism with Parkinson's disease in a Chilean population with a strong Amerindian genetic component

We have studied the association of a null mutation of Glutathione Transferase M1 (GST M1*0/0) with Parkinson's disease (MIM 168600) in a Chilean population with a strong Amerindian genetic component. We determined the genotype in 349 patients with idiopathic Parkinson's disease (174 female and 175 male; 66.84+/-10.7 years of age), and compared that to 611 controls (457 female and 254 male; 62+/-13.4 years of age). A significant association of the null mutation in GST M1 with Parkinson's disease was found (p=0.021), and the association was strongest in the earlier age range. An association of GSTM1*0/0 with Parkinson's disease supports the hypothesis that Glutathione Transferase M1 plays a role in protecting astrocytes against toxic dopamine oxidative metabolism, and most likely by preventing toxic one-electron reduction of aminochrome.

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.

[Association analysis of the parkin gene in patients with sporadic Parkinson's disease from a Han population of Sichuan province]

OBJECTIVE

To determine whether there are any associations between the -258T/G polymorphism of the promoter and the IVS3 -20T/C polymorphism in parkin gene and Parkinson's disease (PD) from a Han population in Sichuan province.

METHODS

Polymerase chain reaction (PCR), restriction fragment length polymorphism, denaturing high performance liquid chromatography(dHPLC) and sequence analysis were used to determine the genotype of each subject. The -258T/G polymorphism and IVS3 -20T/C polymorphism were analysed in 198 patients with sporadic PD and 187 healthy controls, matched for age and gender.

RESULTS

There were significant differences in allele frequency of the -258T/G polymorphism between PD patients and controls, with the G allele more common in cases than controls (52.5% vs 43.3%; chi square is 6.17, P< 0.025, OR is 1.45, 95% CI 1.04-1.86). There were also significant differences in G allele frequency between PD patients with onset age over 50 years old and controls(chi square is 9.048, P< 0.01, OR is 1.57, 95% CI:1.08-2.06). The frequency of TG+GG genotype was significantly higher in PD patients than in controls (78.79% vs 69.51%; chi square is 3.854, P< 0.05, OR is 1.63, 95% CI:0.88-2.38). In addition, there were significant differences in age of onset between PD patients with different genotypes (P< 0.05). The average age of onset in group of GG genotype was later about 5 years compared with the group of TT or TG genotype. The frequency of CC genotype in IVS3 -20T/C polymorphism was much higher than that of TC genotype. No TT genotype was found.

CONCLUSION

This study suggests that the parkin promoter -258T/G polymorphism might be a risk factor for late onset PD in Sichuan. CC genotype for IVS3 -20T/C polymorphism is common in Sichuan Han population. No TT genotype for IVS3 -20T/C polymorphism is found in Sichuan Han population.

Pathogenic mutations in Parkinson disease

Parkinson disease (PD; Parkinson's) is the second most common neurodegenerative disease, characterized by the progressive loss of dopamine neurons and the accumulation of Lewy bodies. Increasing evidence suggests that deficits in mitochondrial function, oxidative and nitrosative stress, the accumulation of aberrant or misfolded proteins, and ubiquitin-proteasome system (UPS) dysfunction may represent the principal molecular pathways that commonly underlie the pathogenesis. The relative role of genetic and environmental factors has been the focus of research and debate. The recent discovery of a number of disease-causing genes (SNCA, Parkin/PARK2, UCHL1, PINK1, DJ1/PARK7, and LRRK2) in familial and sporadic forms of PD has provided considerable insights into the pathophysiology of this complex disorder. The frequency of these gene mutations may vary according to ethnicity and to the specific gene. A gene dosage effect is observed in some cases, and the phenotype of some of the mutation carriers closely resembles typical PD. Penetrance of some of the recurrent mutations is incomplete and may vary with age. Further research to unravel the etiopathology could identify biochemical or genetic markers for potential neuroprotective trials.

BDNF tagging polymorphisms and haplotype analysis in sporadic Parkinson's disease in diverse ethnic groups

Experimental and clinical data suggest that genetic variations in brain-derived neurotrophic factor (BDNF) gene may affect risk for Parkinson's disease (PD). We performed a case-control association analysis of BDNF in three independent Caucasian cohorts (Greek, North American, and Finnish) of PD using eight tagging SNPs and five constructed haplotypes. No statistically significant differences in genotype and allele frequencies were found between cases and controls in all series. A relatively rare BDNF haplotype showed a trend towards association in the Greek (p=0.02) and the Finnish (p=0.03) series (this haplotype was not detected in the North American series). However, given the large number of comparisons these associations are considered non-significant. In conclusion, our results do not provide statistically significant evidence that common genetic variability in BDNF would associate with the risk for PD in the Caucasian populations studied here.

Comparing knowledge and attitudes towards genetic testing in Parkinson's disease in an American and Asian population

INTRODUCTION

Recent discoveries of disease-causing genes in Parkinson's disease (PD) have generated considerable interest regarding genetic testing in PD. The attitudes toward genetic testing are largely influenced by knowledge and preconceived notions.

OBJECTIVE

We investigated the relationship between knowledge of and attitude towards predictive genetic testing of PD in two independent centers in America and Asia involving PD patients and caregivers.

METHODS

In a prospective study involving 515 subjects comprising of PD patients and their caregivers in two independent centers in America and Asia, the level of knowledge about genetic testing and patients' attitudes towards such testing were evaluated using a standardized questionnaire.

RESULTS

American PD patients had a higher level of knowledge of PD genetics than Asian PD (31.1% vs. 12.3%, p=0.0002). A greater number of American PD patients and caregivers reported a positive attitude towards the potential medical benefits of genetic testing compared to their Asian counterparts (85.4% vs. 42.2%, 92.2% vs. 32.1%, p<0.00005), but a more negative attitude towards potential compromise in getting health and life insurance (43.7% vs. 25.8%, p=0.0002). However, in the Asian cohort, multivariate analysis revealed that a high level of genetics knowledge was associated with a positive attitude response regarding the potential medical benefits of testing (p<0.0005), but a negative attitude towards compromises in healthcare and life insurance, getting a job and starting a family (p<0.0005). These associations were not observed amongst American subjects.

CONCLUSIONS

The relationship between level of genetic knowledge and attitude towards potential risks and benefits of predictive genetic testing in PD was distinctly different in two independent, racially and culturally different PD populations and caregivers. These observations have clinical implications in the development of PD genetic counseling programs.