Racial disparities in hospitalization characteristics among Native Hawaiians, Pacific Islanders and Asian American subgroups with Parkinson's disease

BACKGROUND

Differences among Native Hawaiians/Pacific Islanders (NHPI) and Asian American (AA) subgroups have not been adequately studied in Parkinson's disease (PD).

OBJECTIVE

To determine differences in demographics, comorbidities, and healthcare utilization among NHPI, AA subgroups, and White hospitalized PD patients.

METHODS

We conducted a retrospective cross-sectional analysis of Hawai'is statewide registry (2016-2020). Patients with PD were identified using ICD10 code G20 and categorized as White, Japanese, Filipino, Chinese, NHPI, or Other. Variables collected included: age, sex, residence (county), primary source of payment, discharge status, length of stay, in-hospital expiration, Charlson Comorbidity Index (CCI) and Deep Brain Stimulation (DBS) utilization. Bivariate analyses were performed: differences in age and CCI were further examined by multivariable linear regression and proportional odds models.

RESULTS

Of 229,238 hospitalizations, 2428 had PD (Japanese: 31.3 %, White: 30.4 %, Filipino: 11.3 %, NHPI: 9.6 %, Chinese: 8.0 %). NHPI were younger compared to rest of the subgroups [estimate in years (95 % CI): Whites: 4.4 (3.0-5.8), Filipinos: 4.3 (2.7-5.9), Japanese: 7.7 (6.4-9.1), Chinese: 7.9 (6.1-9.7), p < 0.001)]. NHPI had a higher CCI compared to White, Japanese, and Chinese (p < 0.001). Among AA subgroups, Filipinos were younger and had a higher CCI compared to Japanese and Chinese (p < 0.001). There were no significant differences in DBS utilization among subgroups.

CONCLUSIONS

NHPI and Filipinos with PD were hospitalized at a younger age and had a greater comorbidity burden compared to other AAs and Whites. Further research, ideally prospective studies, are needed to understand these racial disparities.

Identification of genetic risk loci and causal insights associated with Parkinson's disease in African and African admixed populations: a genome-wide association study

BACKGROUND

An understanding of the genetic mechanisms underlying diseases in ancestrally diverse populations is an important step towards development of targeted treatments. Research in African and African admixed populations can enable mapping of complex traits, because of their genetic diversity, extensive population substructure, and distinct linkage disequilibrium patterns. We aimed to do a comprehensive genome-wide assessment in African and African admixed individuals to better understand the genetic architecture of Parkinson's disease in these underserved populations.

METHODS

We performed a genome-wide association study (GWAS) in people of African and African admixed ancestry with and without Parkinson's disease. Individuals were included from several cohorts that were available as a part of the Global Parkinson's Genetics Program, the International Parkinson's Disease Genomics Consortium Africa, and 23andMe. A diagnosis of Parkinson's disease was confirmed clinically by a movement disorder specialist for every individual in each cohort, except for 23andMe, in which it was self-reported based on clinical diagnosis. We characterised ancestry-specific risk, differential haplotype structure and admixture, coding and structural genetic variation, and enzymatic activity.

FINDINGS

We included 197 918 individuals (1488 cases and 196 430 controls) in our genome-wide analysis. We identified a novel common risk factor for Parkinson's disease (overall meta-analysis odds ratio for risk of Parkinson's disease 1·58 [95% CI 1·37-1·80], p=2·397 × 10-14) and age at onset at the GBA1 locus, rs3115534-G (age at onset β=-2·00 [SE=0·57], p=0·0005, for African ancestry; and β=-4·15 [0·58], p=0·015, for African admixed ancestry), which was rare in non-African or non-African admixed populations. Downstream short-read and long-read whole-genome sequencing analyses did not reveal any coding or structural variant underlying the GWAS signal. The identified signal seems to be associated with decreased glucocerebrosidase activity.

INTERPRETATION

Our study identified a novel genetic risk factor in GBA1 in people of African ancestry, which has not been seen in European populations, and it could be a major mechanistic basis of Parkinson's disease in African populations. This population-specific variant exerts substantial risk on Parkinson's disease as compared with common variation identified through GWAS and it was found to be present in 39% of the cases assessed in this study. This finding highlights the importance of understanding ancestry-specific genetic risk in complex diseases, a particularly crucial point as the Parkinson's disease field moves towards targeted treatments in clinical trials. The distinctive genetics of African populations highlights the need for equitable inclusion of ancestrally diverse groups in future trials, which will be a valuable step towards gaining insights into novel genetic determinants underlying the causes of Parkinson's disease. This finding opens new avenues towards RNA-based and other therapeutic strategies aimed at reducing lifetime risk of Parkinson's disease.

FUNDING

The Global Parkinson's Genetics Program, which is funded by the Aligning Science Across Parkinson's initiative, and The Michael J Fox Foundation for Parkinson's Research.

Mapping the Diverse and Inclusive Future of Parkinson's Disease Genetics and Its Widespread Impact

Over the last decades, genetics has been the engine that has pushed us along on our voyage to understand the etiology of Parkinson's disease (PD). Although a large number of risk loci and causative mutations for PD have been identified, it is clear that much more needs to be done to solve the missing heritability mystery. Despite remarkable efforts, as a field, we have failed in terms of diversity and inclusivity. The vast majority of genetic studies in PD have focused on individuals of European ancestry, leading to a gap of knowledge on the existing genetic differences across populations and PD as a whole. As we move forward, shedding light on the genetic architecture contributing to PD in non-European populations is essential, and will provide novel insight into the generalized genetic map of the disease. In this review, we discuss how better representation of understudied ancestral groups in PD genetics research requires addressing and resolving all the challenges that hinder the inclusion of these populations. We further provide an overview of PD genetics in the clinics, covering the current challenges and limitations of genetic testing and counseling. Finally, we describe the impact of worldwide collaborative initiatives in the field, shaping the future of the new era of PD genetics as we advance in our understanding of the genetic architecture of PD.

Frequency of Parkinsonism and Parkinson Disease in African Americans in the Chicago Community

BACKGROUND

There is paucity of data about African American (AA) patients with Parkinson's disease (PD) and parkinsonism which may precede PD in older adults. Prior studies suggest that there are lower rates of PD in the AA population, with more cognitive impairment in AA with PD. This study aimed to investigate differences in PD, parkinsonism, and cognition between White and AA populations in 3 longitudinal epidemiologic cohort studies of aging.

METHODS

This study examined parkinsonism, PD frequency, and cognition of community-dwelling older individuals in 3 longitudinal epidemiologic cohort studies. Parkinsonism was based on an exam utilizing the modified Unified Parkinson's Disease Rating Scale performed by a nurse. PD was based on self-report, medications used for treatment of PD, and examination findings. Cognition was assessed using 19 performance-based tests that assess 5 cognitive domains.

RESULTS

AA participants were less likely to have parkinsonism compared to Whites, even with age and gender differences. Frequency of PD was not significant between groups. AA were more likely to have lower cognitive scores as compared to Whites. AA were less likely to have parkinsonism even with controlling for cognitive differences between groups.

CONCLUSIONS

Parkinsonian signs are present among AA in the community at lower rates than in White individuals. Cognitive profiles of AA and Whites with parkinsonism may be different, suggesting differing contributions of pathology to cognitive decline and parkinsonism between groups. Additional research is needed to understand the progression of parkinsonism to PD, as well as to understanding the cognitive differences in AA with parkinsonism.

Associations of ATG7 rs1375206 polymorphism and elevated plasma ATG7 levels with late-onset sporadic Parkinson's disease in a cohort of Han Chinese from southern China

Background: Autophagy-related gene 7 (ATG7) plays a key role in autophagy and is strongly implicated in Parkinson's disease (PD). This study investigated the associations of rs1375206 polymorphism in ATG7 gene promoter and plasma ATG7 levels with late-onset sporadic PD in a cohort of Han Chinese from southern China.Methods: Variant genotypes were identified using polymerase chain reaction-restriction fragment length polymorphism and gene sequencing in 124 patients with late-onset sporadic PD, as well as in 105 age- and sex-matched healthy controls. Plasma ATG7 levels were determined using an enzyme-linked immunosorbent assay.Results: No significant differences in genotype distributions were found between the two groups. Stratification analyses by sex and clinical motor subtypes revealed that the differences remained non-significant in each subgroup (all p > 0.05). Plasma ATG7 protein levels were significantly higher in the PD group than in the control group (p = 0.000). Haplotype analysis demonstrated that the A-T haplotype was significantly associated with late-onset sporadic PD (p = 0.045).Conclusion: Our study suggests that the rs1375206 polymorphism in ATG7 may not be associated with late-onset sporadic PD; however, high plasma ATG7 levels and the A-T haplotype may be associated with susceptibility to late-onset sporadic PD in the Han population from Zhejiang and Guangdong provinces.

Genome-Scale Expression Pattern of Long Non-Coding RNAs in Chinese Uyghur Patients with Parkinson's Disease

BACKGROUND Long non-coding RNAs (lncRNAs) are transcripts thought to regulate gene expression at the post-transcriptional level. Some lncRNAs are associated with Parkinson's disease (PD) and participate in pathological processes of PD. The incidence of PD is relatively high in members of the Uyghur minority living in Xingjiang province of China. This study measured the expression of lncRNAs in the peripheral blood cells of Chinese Uyghur individuals with and without PD and analyzed the possible function of these lncRNAs in the development of PD. MATERIAL AND METHODS Peripheral blood samples were collected from 55 Uyghur patients with PD and 55 healthy volunteers. Total RNA was extracted, and the levels of expression of whole-genome lncRNAs and mRNAs in 10 samples (5 PD and 5 controls) were determined by microarray method. The expression levels of lncRNAs in all 100 subjects were determined by qRT-PCR. The lncRNA expression profiles of PD patients were determined based on lncRNA microarray chip analysis, and differentially expressed lncRNAs were identified. The results of chip analysis were confirmed in a large clinical cohort. RESULTS Comparison of subjects with and without PD identified 32 significantly up-regulated and 18 significantly down-regulated lncRNAs in the PD group. GO analysis showed that mRNAs encoding proteins involved in the regulation of biological processes were differentially expressed, with the inflammatory immune response being the most significantly related pathway. CONCLUSIONS The expression of lncRNAs in peripheral blood differed significantly in PD patients and controls. These differentially expressed lncRNAs may play a role in the development of PD.

Whole exome sequencing identified a new compound heterozygous PRKN mutation in a Chinese family with early-onset Parkinson's disease

Early-onset Parkinson's disease (EOPD) is usually caused by genetic variants and patients with EOPD develop symptoms before the age of 50, accounting for 5% Parkinson's disease (PD). Here we present a Chinese Han pedigree with clinical features of EOPD. To determine the diagnosis and pathogenic mutations of this pedigree, whole exome sequencing, Sanger sequencing and real-time quantitative PCR were performed to detect all the four family members. Our results showed that a new form of compound heterozygous mutation in the PRKN gene, consisting of heterozygous point mutation c.850G > C (p.G284R) along with exon 4 deletion, is the causative genetic factor for EOPD in this pedigree. These discoveries may have implications for genetic counseling, clinical management and developing PRKN target gene therapy strategy.

Prevalence of GBA p.K198E mutation in Colombian and Hispanic populations

We aimed to replicate a recent study that found a high frequency of the GBA p.K198E mutant in Colombian patients with PD. We identified the p.K198E substitution at a lower frequency in our cohort of Colombians with PD (2.1%), and this was not significantly different than controls (1.7%, P = 0.86) emphasizing the need for larger genetic studies in Latin America.

Non-cell autonomous mechanism of Parkinson's disease pathology caused by G2019S LRRK2 mutation in Ashkenazi Jewish patient: Single cell analysis

Parkinson's disease (PD) is the second most prevalent neurodegenerative disease, characterized by the loss of the midbrain dopaminergic neurons, which leads to impaired motor and cognitive functions. PD is predominantly an idiopathic disease, however about 5% of cases are linked to hereditary mutations. The most common mutation in both familial and sporadic PD is the G2019S mutation of leucine-rich repeat kinase 2 (LRRK2) with high prevalence in Ashkenazi Jewish patients and in North African Berber and Arab patients. It is still not fully understood how this mutation leads to PD pathology. In this study, we derived induced pluripotent stem cells (iPSCs) from an Ashkenazi Jewish patient with G2019S LRRK2 mutation to isolate self-renewable multipotent neural stem cells (NSCs) and to model this form of PD in vitro. To investigate the cellular diversity and disease pathology in the NSCs, we used single cell RNA-seq transcriptomic profiling. The evidence suggests there are three subpopulations within the NSCs: a committed neuronal population, intermediate stage population and undifferentiated stage population. Unbiased single-cell transcriptomic analysis revealed differential expression and dysregulation of genes involved in PD pathology. The significantly affected genes were involved in mitochondrial function, DNA repair, protein degradation, oxidative stress, lysosome biogenesis, ubiquitination, endosome function, autophagy and mitochondrial quality control. The results suggest that G2019S LRRK2 mutation may affect multiple cell types in a non-cell autonomous mechanism of PD pathology and that unbiased single-cell transcriptomics holds promise for personalized medicine.

Association between the DRD2 TaqIA gene polymorphism and Parkinson disease risk: an updated meta-analysis

BACKGROUND

DRD2 TaqIA polymorphism may be associated with an increased risk of developing Parkinson disease (PD). However, the individual study's results are still inconsistent.

METHODS

A meta-analysis of 4232 cases and 4774 controls from 14 separate studies were performed to explore the possible relationship between the DRD2 TaqIA gene polymorphism and PD. Pooled odds ratios (ORs) for the association and the corresponding 95% confidence intervals (CIs) were evaluated by a fixed-effect model.

RESULTS

The pooled results revealed a significant association between DRD2 gene TaqIA polymorphism under recessive genetic model (OR: 0.91, 95% CI:0.83,0.99, P = .031) and additive genetic models (OR:0.93,95%CI:0.87,0.99, P = .032), but not associated with PD susceptibility under other genetic models in the whole population. Moreover, subgroups based on ethnicity and genotyping methods showed this association in the Caucasian subgroup under recessive genetic model (OR: 0.85, 95% CI:0.76,0.95, P = .003) and additive genetic models (OR:0.87,95%CI:0.79,0.96, P = .004) were existed. Besides, no significant association was detected under 6 genetic models in the Asian populations and PCR-RFLP subgroup.

CONCLUSIONS

The current meta-analysis suggested that a significant association between DRD2 TaqIA polymorphism and PD under the recessive genetic mode, and additive genetic models, especially in Caucasians.

Association of polymorphisms in the MCP-1 and CCR2 genes with the risk of Parkinson's disease

Studies investigating the impact of polymorphisms on monocyte chemotactic protein-1 (MCP-1) and CC chemokine receptor (CCR2) on the susceptibility of Parkinson's disease (PD) have reported inconsistent results. Owing to mixed and inconclusive results, we conducted a meta-analysis to systematically summarize and clarify the association between the two gene polymorphisms and PD risk. We performed a meta-analysis of five eligible studies to summarize the data describing the association between PD risk and polymorphisms in MCP-1 A2518G and CCR2 V64I. The association was evaluated by calculating the odds ratios (ORs) with the corresponding 95% confidence intervals (CIs). A significant increased risk of PD was observed in the MCP-1 A2518G polymorphism in allele model (G vs. A: OR 1.12, 95% CI 1.01-1.25, p = 0.03). The dominant model of MCP-1 A2518G genotype showed no significant association with PD risk, while the risk tendency was increased (AG + GG vs. AA: OR 1.20, 95% CI 1.00-1.42, p = 0.05). In addition, CCR2 V64I polymorphism showed no significant association with PD risk (I vs. V: OR 0.33, 95% CI 0.06-1.92, p = 0.22; VI + II vs. VV: OR 1.00, 95% CI 0.83-1.21, p = 0.99). In subgroup analysis by ethnicity, no significant difference was found in both Caucasians and Asians between CCR2 V64I polymorphism and PD risk, while a significant statistical association was identified in Asians between MCP-1 A2518G polymorphism and PD risk. When the data were stratified by study area, the increased risk of PD was observed only in studies conducted in China. In summary, the present meta-analysis suggests that genetic polymorphisms of MCP-1 A2518G may influence the susceptibility of PD in Asian countries, especially in China. However, CCR2 V64I polymorphism is not correlated with PD risk. The results should be interpreted with caution due to limited sample and heterogeneity. Large scale and well-designed studies are needed to validate our findings.

Neuropsychiatric Symptoms and Cognitive Impairment in Chinese Patients with Parkinson's Disease in Han and Hui Ethnicity

Neuropsychiatric symptoms are common in patients with Parkinson's disease (PD) and they are likely to outweigh the motor symptoms and become a major factor affecting the quality of life of PD patients. However, the studies focusing on the non-motor symptoms in Chinese PD patients from different ethnicity are scarce. The aim of this retrospective study was to investigate neuropsychiatric symptoms and cognitive impairment in Chinese PD patients from Han and Hui populations from central China. Seventy-two Han Chinese PD patients (Han PD group) and 71 age-and sex-matched Hui Chinese PD patients (Hui PD group) were enrolled from Zhongnan Hospital of Wuhan University between Sept. 2011 and Aug. 2014 in the study. The neuropsychiatric symptoms and cognitive impairment were assessed using Neuropsychiatric Inventory (NPI) and Mini Mental State Examination (MMSE). We found that the proportion of depression, anxiety, apathy, irritability, euphoria and night time behavior disturbances were higher in the Han PD group than in the Hui PD group (P<0.05 or P<0.01). But the proportion of delusion, hallucination, agitation, disinhibition, aberrant motor behavior and change in appetite were not significantly different between the Han PD group and the Hui PD group (P>0.05). The total mean scores of the MMSE from patients in the Han PD group were similar to those in the Hui PD group (P>0.05). However, the subscale scores of recall domain and language domain in the Han PD group were significantly different from those in the Hui PD group (P<0.05). No significant difference was noted in the orientation, memory and calculation domains between the two PD groups (P>0.05). This study first showed the recall domain and language domain were different between the Han PD patients and the Hui PD patients. Depression, anxiety, apathy, irritability, euphoria and night time behavior disturbances were less presented in the Hui PD patients. All these differences may be related to the different ethnicity, which would be helpful for clinical physicians to recognize the different non-motor symptoms in Chinese PD patients with different ethnicity.

The genetic association between apolipoprotein E gene polymorphism and Parkinson disease: A meta-Analysis of 47 studies

OBJECTIVE

Although the relationship between apolipoprotein E (ApoE) gene polymorphisms and the risk of Parkinson disease (PD) has been established, the results were inconsistent and inconclusive.

METHODS

A comprehensive search examining the association between APOE polymorphisms and PD through PubMed, Embase, Chinese National Knowledge Infrastructure (CNKI), and Cochrane Library databases was performed without published year limited.

RESULTS

A total of 47 studies with 7533 cases and 14442 controls were included in present study. The results showed statistically significant association between risk factor ApoE ε4 allele and PD in Asian population (P = .003, odds ratio, OR [95% confidence interval, CI] = 1.43 [1.13,1.80]). Genotype ε2ε4 have significantly associated with PD in Asian population (P = .004, OR [95% CI] = 4.43 [1.62,12.10]). Genotype ε3ε4 was significantly associated with PD in Latin-American population (P = .01, OR [95% CI] = 1.44 [1.08,1.91]). In addition, the frequency of the genotype ε3ε4 is lower in PD group than that in the control group in Caucasian population, and the difference of genotype ε3ε4 is also statistically significant (P = .006, OR [95% CI] = 0.86 [0.77,0.96]). Although significant heterogeneity was observed among all studies, the results were shown to be stabilized by sensitive analysis. No publish bias was observed.

CONCLUSIONS

This meta-analysis suggests that the APOE ε4, but no ε2, might be a risk factor for PD in Asian population. Furthermore, the genotype ε2ε4 may be a susceptible factor for PD in Asian population, and the genotype ε3ε4 may be a susceptible factor for PD in both Caucasian and Latin-American populations.

New endemic familial parkinsonism in south Moravia, Czech Republic and its genetical background

An increased prevalence of familial neurodegenerative parkinsonism or cognitive deterioration was recently found in a small region of southeastern Moravia.The aim of the study was to assess the genetic background of this familial disease.Variants in the ADH1C, EIF4G1, FBXO7, GBA + GBAP1, GIGYF2, HTRA2, LRRK2, MAPT, PRKN, DJ-1, PINK1, PLA2G6, SNCA, UCHL1, VPS35 genes were examined in 12 clinically positive probands of the pedigree in which familial atypical neurodegenerative parkinsonism was identified in previous epidemiological studies. Libraries were sequenced by massive parallel sequencing (MPS) on the Personal Genome Machine (PGM; Ion Torrent). Data were analyzed using Torrent Suite and IonReporter software. All variants were then verified and confirmed by Sanger sequencing.We identified 31 rare heterozygous variants: 11 missense variants, 3 synonymous variants, 8 variants in the UTR region, and 9 intronic variants. Six variants (rs1801334, rs33995883, rs35507033, rs781737269, rs779760087, and rs63750072) were evaluated as pathogenic by at least one in-silico predictor.No single "founder" pathogenic variant associated with parkinsonism has been found in any of the probands from researched pedigree. It may rather be assumed that the familial occurrence of this disease is caused by the combined influence of several "small-effect" genetic variants that accumulate in the population with long-lasting inbreeding behavior.

Prevalence and risk factors for depression and anxiety in Chinese patients with Parkinson disease

BACKGROUND

Anxiety and depression are common in Parkinson disease and both are important determinants of quality of life in patients. Several risk factors are identified but few research have investigated general and Parkinson's disease (PD)-specific factors comprehensively. The aim of this work was to explore PD-specific and -non-specific risk factors for PD with depression or anxiety.

METHODS

A cross-sectional survey was performed in 403 patients with PD. Multivariate logistic analysis was used to investigate the prevalence and risk factors for the depression and anxiety in PD. The data of patients included demographic information, medicine history, disease duration, age at onset (AAO), family history, anti-parkinsonism drug, modified Hoehn and Yahr staging (H-Y) stage, scales of motor and non-motor symptoms and substantia nigra (SN) echogenic areas.

RESULTS

403 PD patients were recruited in the study. Depression and anxiety were present in 11.17% and 25.81% respectively. Marital status, tumor, higher Movement Disorder Society-sponsored revision of the Unified Parkinson's Disease Rating Scale (MDS-UPDRS) II score, dyskinesia, higher Hamilton Anxiety Rating Scale (HARS) score and lower the Parkinson's disease sleep scale (PDSS) score were associated with depression in PD. female gender, higher rapid eye movement behavior disorder Questionnaire-Hong Kong (RBD-HK) score, higher Hamilton Deprssion Rating Scale (HAMD) score, higher the scale for outcomes in PD for autonomic symptoms (SCOPA-AUT)score and larger SN echogenic areas were associated with anxiety. Neither depression nor anxiety was related to any anti-parkinsonism drugs.

CONCLUSIONS

The prevalence of depression and anxiety in the current PD patients was 11.17% and 25.81% respectively. Disease of tumor, currently having no partner, severer motor function, dyskinesia, poorer sleep quality and anxiety were risk factors for PD with depression. Female, depression, rapid eye movement behavior disorder (RBD), autonomic dysfunction and larger SN area were risk factors for PD with anxiety.

Association of DNMT3b gene variants with sporadic Parkinson's disease in a Chinese Han population

BACKGROUND

Parkinson's disease (PD) is the second most common neurodegenerative disorder worldwide. Epigenetic modifications, specifically DNA methylation, have been implicated in the development of this disease. Genetic variants of DNA methyltransferase 3b (DNMT3b), one of the most important DNA methyltransferases, were shown to be associated with PD in a Brazilian population. However, it is unclear whether genetic variants of DNMT3b increase the risk of PD in the Chinese Han people. The present study aimed to investigate the association of the DNMT3b variants rs2424913, rs998382 and rs2424932 with PD in a Chinese Han population.

METHODS

We studied 487 Chinese Han patients with sporadic PD and 485 healthy age-, sex- and ethnicity-matched controls. DNA was extracted from peripheral blood leukocytes and the individual genotypes were determined using the SNaPshot method.

RESULTS

We found that the rs2424932 and rs998382 variants were significantly associated with an increased risk of PD compared to the controls [rs2424932: odds ratio (OR) = 1.632, 95% confidence interval (CI) = 1.108-2.406, p = 0.013; rs998382: OR = 1.612, 95% CI = 1.103-2.382, p = 0.014]. Subgroup analysis suggested that female patients carrying the rs2424932 or rs998382 variants were more likely to develop PD than female controls (rs2424932: OR = 3.863, 95% CI = 2.004-7.445, p < 0.001; rs998382: OR = 3.679, 95% CI = 1.943-6.964, p < 0.001). Haplotype analysis indicated that the three variants comprised one block and that the Trs2424913 -Crs998382 -A rs2424932 haplotype was correlated with an increased risk of PD (p = 0.0046), especially for Chinese Han females (p < 0.0001).

CONCLUSIONS

The results of the present study strongly suggest that DNMT3b variants are associated with PD in the Chinese Han people, especially females.

Hospitalization and rehospitalization in Parkinson disease patients: Data from the National Parkinson Foundation Centers of Excellence

Background

Patients with Parkinson disease (PD) are at high risk of hospital encounters with increasing morbidity and mortality. This study aimed to determine the rate of hospital encounters in a cohort followed over 5 years and to identify associated factors.

Methods

We queried the data from the International Multicenter National Parkinson Foundation Quality Improvement study. Multivariate logistic regression with backward selection was performed to identify factors associated with hospital encounter prior to baseline visit. Kaplan-Meier estimates were obtained and Cox regression performed on time to hospital encounter after the baseline visit.

Results

Of the 7,507 PD patients (mean age 66.5±9.9 years and disease duration 8.9±6.4 years at baseline visit), 1919 (25.6%) had a history of a hospital encounter prior to their baseline visit. Significant factors associated with a history of a hospital encounter prior to baseline included race (white race: OR 0.49), utilization of physical therapy (OR 1.47), history of deep brain stimulation (OR 1.87), number of comorbidities (OR 1.30), caregiver strain (OR 1.17 per standard deviation), and the standardized Timed Up and Go Test (OR 1.21). Patients with a history of hospitalization prior to the baseline were more likely to have a re-hospitalization (HR1.67, P<0.0001) compared to those without a prior hospitalization. In addition, the time to hospital encounter from baseline was significantly associated with age and number of medications. In patients with a history of hospitalization prior to the baseline visit, time to a second hospital encounter was significantly associated with caregiver strain and number of comorbidities.

Conclusion

Hospitalization and re-hospitalization were common in this cohort of people with PD. Our results suggest addressing caregiver burden, simplifying medications, and emphasizing primary and multidisciplinary care for comorbidities are potential avenues to explore for reducing hospitalization rates.

Parkinson’s disease among Inuit in Greenland: organochlorines as risk factors

OBJECTIVES

In the present study we investigate organochlorines as possible risk factors for Parkinson's disease (PD) in an arctic population. This has never been done before.

STUDY DESIGN

Case-control study of Inuit in Greenland.

MATERIALS AND METHODS

Plasma from 31 PD (20 males and 11 females) (mean age 69 yr) and 122 controls (57 males and 65 females) (mean age 61 yr) was analysed for 31 PCBs and pesticides by dual-column GC-ECD and GC-NCI/MS.

RESULTS

Plasma concentrations of PCBs and pesticides were markedly increased in both PD and controls. The concentrations did not differ between the PD cases and controls. However, the mean DDE concentration was higher in PD than in controls (42.1 and 15.0 microg/l, respectively, and with a wide range among the PD cases). The difference was significant for log transformed DDE values after control for age and sex (p=0.005).

CONCLUSION

A few epidemiological studies indicate a possible connection between exposure to pesticides and PD. The idea that exposure to organochlorines may be an important risk factor for PD among the Inuit in Greenland requires more investigations.

Genetic analysis of the CHCHD2 gene in a cohort of Chinese patients with Parkinson disease

CHCHD2 has been recently reported as a causative gene for autosomal dominant Parkinson disease (ADPD) in Japanese populations. Further genetic studies of CHCHD2 in other populations are needed. Herein, we sequenced CHCHD2 gene in 162 patients (90 from ADPD pedigrees, 72 with sporadic Parkinson disease) and 90 healthy controls in Chinese population. We observed 5 exonic variants (c.-34C>A, c.-9T>G, c.5C>T, c.*125G>A, c.*154A>G) including 1 novel variant. No pathogenic mutation was found, suggesting that CHCHD2 mutations may be rare in Chinese ADPD patients.

Validation of Neuropsychological Tests to Screen for Dementia in Chinese Patients With Parkinson's Disease

To compare the accuracy of different neuropsychological tests and their combinations for deriving reliable cognitive indices for dementia diagnosis in Parkinson's disease (PD). One hundred forty consecutive patients with PD were recruited and administrated an extensive battery of neuropsychological tests. Discriminant analysis and receiver-operator characteristic curve were used to evaluate their correct classifications and validity. Patients with PD having dementia (PDD; 23.5%) performed significantly worse in all tests than patients without dementia. Age of onset, disease duration, Hoehn-Yahr grade, Unified Parkinson's Disease Rating Scale part III scores, and education were associated with dementia in patients with PD. Mini-Mental State Examination (MMSE), Montreal Cognitive Assessment, and Block Design (BD) showed better specificity and sensitivity when used alone, and combined use of MMSE and BD further increased the validity. Our results indicated that the accuracy of MMSE was better in dementia diagnosis of Chinese patients with PD, and combined use of MMSE and BD could further increase the validity of dementia diagnosis.

The GBA, DYRK1A and MS4A6A polymorphisms influence the age at onset of Chinese Parkinson patients

Parkinson's disease (PD) is known as the most common neurodegenerative disease after Alzheimer's disease (AD). The precise pathogenic mechanism of PD remains unclear, but genetic and environmental factors are widely recognized to be associated with it. Although many associated genes have been discovered, they account for only a few PD patients. Recently, there are growing evidences indicating that patients with PD and AD share similarities in clinical features, pathology and genetic risks. However, no study has been conducted on the relations between AD associated genes and age at onset (AAO) of PD. In this study, we have detected 14 single nucleotide polymorphisms (SNPs) in 9 AD genome wide association studies top hit genes and 4 SNPs in 4 PD-cognitive impairment related genes among 297 Chinese PD patients. Through the linear regression analysis, we identified the significant associations of the GBA L444P mutation and DYRK1A rs8126696 T allele with the earlier AAO in PD patients, and the A allele at MS4A6A rs610932 with the delayed AAO of PD. This is the first report of significant associations of DYRK1A and MS4A6A SNPs and the AAO of PD. On account of their effects both in AD and PD, it is indicated that AD and PD possibly share some common pathways.

Genetic analysis of TREM2 variants in Chinese Han patients with sporadic Parkinson's disease

Parkinson's disease (PD) is the second most common neurodegenerative disorder after Alzheimer's disease and is characterized by the degeneration of dopaminergic neurons in substantia nigra. Recently, rs75932628 (p.R47H) of the triggering receptor expressed on myeloid cells 2 gene (TREM2) was identified to be associated with PD in American, Spanish, Irish, and Polish population. To explore whether TREM2 variants are related to susceptibility of sporadic PD in Chinese Han population, we designed a case-control comparison study and studied two variants rs75932628 (p.R47H) and rs2234253 (p.T96K) of the TREM2 gene in 512 Chinese Han patients with sporadic PD and 512 age, gender and ethnicity matched normal controls from Mainland China. No variant for either rs75932628 or rs2234253 was found in both PD and control cohorts. Our data suggest that neither variant rs75932628 nor rs2234253 be a major susceptibility factor of sporadic PD in Chinese Han population from Mainland China.

Association of the mt-ND2 5178A/C polymorphism with Parkinson's disease

Mitochondria play an important role in the etiology of Parkinson's disease (PD). While mutations in the mitochondrial DNA (mtDNA) have been shown to accumulate in PD, no specific mtDNA polymorphisms have been associated with susceptibility or resistance to PD. A cytosine to adenine transversion at base pair 5178 in the mtDNA has been associated with increased longevity and resistance against a number of age related disorders and has been shown to decrease mitochondrial reactive oxygen species (ROS) production. We sought to determine whether 5178A is associated with resistance against PD in a Han Chinese population. To assess its association with PD, we genotyped 484 idiopathic PD patients and 710 control individuals for 5178C/A. Genotyping was performed using restriction fragment length polymorphism (RFLP) analysis. There was no significant association between 5178A and PD (P=0.308) when analyzing the entire population. However, sub-group analysis revealed that in males the frequency of 5178A was significantly lower in PD patients (27.7% in controls vs 20.0% in PD patients, P=0.027). Stratification of the population by age showed that this trend held across age groups but only reached statistical significance in males aged 60-70 (29.1% in controls vs 14.05 in PD patients, P=0.011). In conclusion, we demonstrated that the frequency of 5178A was significantly decreased in male PD patients in a Han Chinese population. This polymorphism may be associated with resistance against the development of PD when in combination with loci on the Y chromosome.

α-Synuclein rs356219 polymorphisms in patients with Gaucher disease and Parkinson disease

Mutations in β-glucocerebrosidase, the genetic defect in Gaucher disease (GD), are an important susceptibility factor for Parkinson disease (PD). A PD effector is α-synuclein (SNCA) hypothesized to selectively interact with β-glucocerebrosidase under lysosomal conditions. SNCA polymorphism rs356219 may be associated with early-age-onset PD, common among patients with GD+PD. The objective of this study was to ascertain rs356219 genotypes of GD+PD patients. All GD+PD patients at our Gaucher referral clinic were asked to participate. A GD-only sex-, age-, GD genotype-, and enzyme therapy (ERT)-matched control was found for each GD+PD participant. Student's t-test was used (p-value <0.05 as significant). There were 14 GD+PD patients: all Ashkenazi Jewish; 11 males (78.6%); mean (range) age diagnosed GD 34.2 (5-62) years; 50% N370S homozygous; mild to moderate GD; 3 asplenic and only these have osteonecrosis; 5 received ERT; mean age (range) diagnosed PD was 57.8 (43-70) years; first PD sign was tremor in 9 (64.3%); cognitive dysfunction in all. In GD+PD, frequency for AG+GG (9) was greater than AA (5); in GD only, there was equality (7). Odds Ratio risk for PD increases with number minor alleles: but not significantly greater among GD+PD than GD only; in aggregate, there was no difference between cohorts for frequency of minor alleles. The limitation of this study is few GD+PD, albeit virtually all the GD+PD cohort >500 adult GD patients in our clinic. Nonetheless, as a foray into potential genetic GD susceptibility for a synucleinopathy, this study suggests the need for collaboration to achieve larger sample size.

Association analysis of STK39, MCCC1/LAMP3 and sporadic PD in the Chinese Han population

With the completion of the Human Genome Project, GWAS have been widely used in exploring the genetic studies of complex diseases. A meta-analysis of datasets from five Parkinson's disease GWAS from the USA and Europe found 11 loci that surpassed the threshold for genome-wide significance (p<5×10(-8)), and five were newly identified loci (ACMSD, STK39, MCCC1/LAMP3, SYT11 and CCDC62/HIP1R). Another GWAS of the Ashkenazi Jewish population also identified loci in STK39 and LAMP3. Because the association between the STK39 and MCCC1/LAMP3 genes and PD was confirmed in different populations, we conducted a case-control cohort to clarify the association between the four single nucleotide polymorphism (SNP) loci (rs2102808 and rs3754775 in the STK39; rs11711441 and rs12493050 in the MCCC1/LAMP3) and PD in the Chinese Han population. Polymerase chain reaction and direct DNA sequencing analyses were used to detect the four variations in a case-control cohort comprised of 993 ethnic Chinese subjects. We found that in the detection of the rs11711441, there was a significant difference between ungrouped populations, early-onset PD, late-onset PD, male PD, female PD and the corresponding control group in allele and genotype frequency (p<0.001, OR<1). In the detection of the rs2102808, rs3754775 and rs12493050, ungrouped populations, early-onset PD, late-onset PD, male PD or female PD with the corresponding control group showed no significant difference in allele and genotype frequency (p>0.0125). Our findings suggested that the allele G of rs11711441 of the MCCC1/LAMP3 gene can decrease the risk of PD in Chinese population. No statistically significant difference in genotype frequency between cases and controls was observed for the other three SNPs.

[Association between polymorphism of dopamine β-hydroxylase gene and Parkinson's disease in Uygurs and Hans of Xinjiang]

OBJECTIVE

To explore the relationship between dopamine β-hydroxylase gene polymorphisms and Parkinson's disease (PD) in Uygurs and Hans populations of Xinjiang.

METHODS

The polymorphisms of DBH gene were determined by polymerase chain-reaction restriction fragment length polymorphism (PCR-RFLP) in 239 PD patients (including 100 Uygurs and 141 Hans) and 232 health controls (including 103 Uygurs and 129 Hans).

RESULTS

The genotypic or allelic distribution of DBH gene had significant differences between PD and control groups in both Uygur and Han populations (P < 0.05). The genotypic or allelic frequencies were significantly different between Han PD and control groups (P < 0.05). The genotypic or allelic frequencies in those aged 65 years or above were significantly different from that in others (P < 0.05). There was a significant increase of PD in A2 allele carriers (OR = 1.965, P < 0.05). And the frequencies of A2 allele in female PD patients were higher than those in female controls (P < 0.05) and A2 allele carriers had a significant increase of PD (OR = 1.696, P < 0.05).

CONCLUSION

Different between Uygurs and Hans of Xinjiang, DBH5 TaqI polymorphisms may be associated with PD in Hans. A2 allele carriers are often found in females and those aged 65 years or above.

[Comparison of clinical symptoms for Uygur and Han Parkinson's disease patients]

OBJECTIVE

To explore the characteristics of clinical symptoms in Uygur and Han patients with Parkinson's disease (PD).

METHODS

The unified Parkinson's disease rating scale (UPDRS), Hoehn-Yahr, mini-mental state examination (MMSE) scale, Alzheimer disease cooperative study-activities of daily living (ADCS-ADL) and neuropsychiatric inventory (NPI) were administered to 91 Uygur and 173 Han PD patients from Xinjiang Urumqi and surrounding region from June 2008 to September 2011 to compare the characteristics of clinical symptoms between Uygur and Han patients.

RESULTS

The subjects of drug treatment in Han [108 (62.34%)] were more than in Uygur [36 (39.56%), (P < 0.05)]. However there were no significant differences in the subjects of effective treatment between two groups (P > 0.05). No significant inter-group differences existed in the scores of Hoehn-Yahr (P > 0.05). Compare with moderate and severe group in Hoehn-Yahr, there were no significant differences in the scores of ADL, UPDRS II and UPDRS III between two groups (P > 0.05). The subjects of resting tremor, increased muscle tone and bradykinesia as the presenting symptoms in Uygur [8 (19.05%)] were more than in Han [7 (7.07%), (P < 0.05)]. And the subjects of N-type progressive in Uygur [36 (85.71%)] were more than in Han [48 (48.48%), (P < 0.05)]. There were no significant differences in other presenting symptoms, initial site, on-off phenomenon and dyskinesia between two groups (P > 0.05). No significant differences existed in the scores of MMSE and NPI between two groups (P > 0.05).

CONCLUSION

No significant differences exist in typical motor symptoms, severity of disease, activities of daily living, cognitive dysfunction and psychiatric symptoms between Uygur and Han. But N-type progressive is more common in Uygur. And the presenting symptoms of resting tremor, increased muscle tone and bradykinesia are also higher in Uygur.

Prevalence of nocturia in Parkinson's disease patients from various ethnicities

OBJECTIVES

One of the most common non-motor symptoms in Parkinson's disease (PD) is nocturia. This paper seeks to address the prevalence of nocturia in PD and correlate it to various factors such as gender, Hoehn and Yahr (H&Y) stage, age, and ethnicities.

METHODS

In particular, 332 PD patients were seen in a community movement disorders clinic and their charts were analyzed from 2005 to 2010. Within this population, more than one-third (34.9%) patients were diagnosed with nocturia.

RESULTS

Age, gender, and PD stage were significant predictors of nocturia in PD. With every one-year increase in age, the odds of developing nocturia in PD increases by 3.1% while an increase in H&Y stage increases the odds of nocturia in PD by 1.645 times. Also, males had greater odds of experiencing nocturia in PD. Ethnicities alone were of no significant importance. However, after performing interaction analyses, Asian and Indian males, especially, were at significantly greater risk than other ethnicities.

DISCUSSION

Future research is indeed required to understand why certain ethnicities are especially at risk. Clinicians must also be aware of the epidemiology of nocturia in PD to prevent and treat this debilitating symptom.

Genetic analysis of the S100B gene in Chinese patients with Parkinson disease

There is growing evidence that genetic abnormalities play an important role in the pathogenesis of Parkinson disease (PD). At least 18 genetic loci and 13 disease-related genes for parkinsonism have been identified. The S100 calcium-binding beta (S100B), which is expressed and secreted by astrocytes, has been found to be associated with PD. To evaluate whether the S100B variants are related to PD in Chinese Han population, we conducted genetic examination of the S100B gene in 502 PD patients from Mainland China. We did identify two known variants c.279+4T>C (rs187503470) and c.99C>G (p.Leu33Leu, rs1051169) in our patients. Neither of these two variants is predicted to change amino acid or splice site, indicating that they are not pathogenic mutations. Our results suggest that mutations in the coding region or intron/exon boundaries of the S100B gene play little or no role in the development of PD in Chinese population.

Association studies of MMP-9 in Parkinson's disease and amyotrophic lateral sclerosis

Parkinson’s disease (PD) and amyotrophic lateral sclerosis (ALS) share several clinical and neuropathologic features, and studies suggest that several gene mutations and polymorphisms are involved in both conditions. Matrix metalloproteinase-9 (MMP-9) is implicated in the pathogenesis of PD and ALS, and the C(−1562)T polymorphism in the MMP-9 gene leads to higher promoter activity. We therefore investigated whether this polymorphism predisposes to both PD and sporadic ALS (sALS). Samples from 351 subjects with PD and 351 healthy controls from two major cities in China were compared, while samples from 226 subjects with sALS were compared to the same number of controls from three centers in China. A possible association between the C(−1562)T polymorphism in the MMP-9 gene and PD or sALS was assessed by restriction fragment length polymorphism (RFLP) analysis. Our results show a significant association between the C(−1562)T polymorphism in the MMP-9 gene and risk of PD (odds ratio = 2.268, 95% CI 1.506–3.416, p<0.001) as well as risk of sALS (odds ratio = 2.163, 95% CI 1.233–3.796, p = 0.006), supporting a role for MMP-9 polymorphism in the risk for PD and sALS.

Patterns of linkage disequilibrium of LRRK2 across different races: implications for genetic association studies

Genome Wide Association Studies (GWASs) have identified trait-associated polymorphisms via a hypothesis-free approach. However, it is challenging when attempting to reproduce GWAS findings in different populations as it fundamentally relies on the similar patterns of linkage disequilibrium (LD) between the unknown causal variants and the genotyped single nucleotide polymorphisms (SNPs). To address this potential limitation, we examined the regional LD pattern of leucine-rich repeat kinase 2 (LRRK2) gene, which is responsible for both autosomal dominant and sporadic Parkinson’s disease (PD), in Caucasians (CEU), Japanese (JPT) and Chinese (CHB) from HapMap and Chinese (CHS), Malays (MAS) and Indians (INS) from the Singapore Genome Variation Project (SGVP) utilizing the traditional heatmaps and targeted analysis of LRRK2 gene via Monte Carlo simulation through varLD scores of these ethnic groups. Both heatmaps and targeted analysis showed that LD pattern of JPT was different from that of INS (P=0.0001); while LD pattern of CEU was different from that in Asian except for INS (all P=0.0001). Our study suggests that there is a higher chance to detect associations between PD and those trait-associated SNPs of LRRK2 gene found in Caucasian studies in INS, while those found in Japanese studies are likely to be better replicated among CHB.

MCCC1/LAMP3 reduces risk of sporadic Parkinson's disease in Han Chinese

BACKGROUND

A recent large-scale replication and heterogeneity study reported the new described GWAS locus (MCCC1/LAMP3 rs11711441) was associated with a reduced risk of Parkinson disease (PD) in Asian and Caucasian populations. Its role is still unknown in a Han Chinese population from mainland China. We genotyped the rs11711441 variant to investigate the association with risk of PD.

METHODS

Using a case-control methodology, a total of 1428 Han Chinese study subjects were genotyped. We also conducted further stratified analysis according to age at onset and compared the clinical characteristics of GA + AA subjects with GG subjects.

RESULTS

In this study, we confirmed that the A allele of MCCC1/LAMP3 (rs11711441) polymorphism reduces the risk to develop sporadic PD (P = 0.043). Additionally, subjects with GA + AA genotypes have a reduced risk compared to those with GG genotype (P = 0.022). The association was seen among the older age group (P = 0.014), but was not significant among the younger age group (P = 0.641). No significant differences were observed in gender, age at onset, and onset symptoms between GA + AA subjects and GG subjects.

CONCLUSION

Our study, the first from Mainland China demonstrates that MCCC1/LAMP3 (rs11711441) is associated with a lower risk of PD. Further studies in additional Chinese populations and other cohorts will be useful.

Lack of association between BST1 polymorphisms and sporadic Parkinson's disease in a Japanese population

Several genome-wide association studies and case-control studies have investigated the relationships between single nucleotide polymorphisms (SNPs) in the BST1 gene and Parkinson's disease (PD), but the results have been inconsistent. We examined the relationships between SNPs rs11931532, rs12645693, and rs11724635 and the risk of sporadic PD in Japan. Included were 229 cases within 6years of onset of PD as defined according to the UK PD Society Brain Bank clinical diagnostic criteria. Controls were 357 inpatients and outpatients without neurodegenerative disease. SNPs rs11931532 and rs12645693 were not significantly related to sporadic PD. Compared with a reference group of subjects with the CC genotype of SNP rs11724635, those with the AA genotype had a marginally significantly increased risk of sporadic PD: the adjusted OR was 1.57 (95% CI: 0.95-2.61, P=0.08). No significant interactions were found between BST1 SNP rs11724635 and smoking or caffeine intake with respect to sporadic PD. The current study failed to detect significant relationships between BST1 SNPs rs11931532, rs12645693, and rs11724635 and sporadic PD; however, the relationship between SNP rs11724635 and sporadic PD was of borderline significance. We do not find evidence for interactions between smoking or caffeine intake and SNP rs11724635 affecting sporadic PD.

LRRK2 A419V is not associated with Parkinson's disease in different Chinese populations

It has been suggested that a common LRRK2 polymorphic variant (A419V (rs34594498 C >T)) may be a risk factor among Asians (especially in Taiwan). In this study, we examined this variant in a larger and independent Taiwan cohort. We found the frequency of the variant (A419V) to be very rare in our Taiwan PD and controls (?0.6%). Further studies were conducted in two other Chinese populations (Singapore and China), comprising of a total of 3004 subjects including 1517 PD patients and 1487 control subjects. However, our multi-center Chinese study revealed that the frequency of the variant was rare (?0.4%) and was not associated with risk of PD, suggesting that the variant is not a major risk factor for PD among Chinese, at least in our study population.

PARK2 gene mutations in early onset Parkinson's disease patients of South India

With the etiology being unclear till date, a combination of age, genetic and environmental factors are known to play a significant role in the pathogenesis of Parkinson's disease. Mutations in PARK2 gene have been implicated to cause autosomal recessive early onset PD. We analyzed the 12 coding exons of PARK2 gene in 16 early onset PD patients of South Indian ethnicity. PARK2 mutations were present in 68% of the early onset cases. We report the presence of four PARK2 sequence variants c.1239G>C, c.171+25T>C, c.202A>G, c.601G>A, and a novel insertion mutation, c.798_799insA in the exon 7 of PARK2 gene. These results suggest that mutations in PARK2 gene may be a common cause of PD among South Indian early onset patients.

Penetrance of LRRK2 G2385R and R1628P is modified by common PD-associated genetic variants

Variants in the LRRK2 gene are well-characterized genetic predisposing factors for PD worldwide, and LRRK2-associated PD is often indistinguishable from idiopathic PD (IPD). However, considerable heterogeneity of LRRK2-PD suggests the existence of additional genetic and/or environmental modifiers for LRRK2 carriers, which have yet to be confirmed by large-scale human studies. In a Chinese cohort consisting of 2013 sporadic PD patients and 1971 controls, we investigated the modification of the two Asian-specific LRRK2 variants, G2385R and R1628P, by variants of five other PD-associated genes/loci (SNCA, MAPT, GBA, BST1, PARK16). Of all the PD patients, 13.1% carried LRRK2 G2385R and/or R1628P variant. Among these carriers, a total of 15 different polygenic genotypes were detected representing different combination patterns between LRRK2 variants and those of the other genes/loci, which, alone or in combination, significantly modified the LRRK2-related risk for PD and the patients' ages at onset (AAOs). These results not only represent the largest replication data affirming the association between PD and all the six genes/loci in Chinese, but for the first time suggest that multiple PD-associated genetic factors modify both the penetrance and AAO of LRRK2 parkinsonism. This finding may have important implications for elucidating pathophysiologic mechanisms relevant to both LRRK2-associated and idiopathic PD. However, testing interactions among multiple genes by genetic association studies is still challenging. Future studies with much larger sample sizes are needed to confirm our findings.

Association study of SCARB2 rs6812193 polymorphism with Parkinson's disease in Han Chinese

Recently, a nucleotide polymorphism rs6812193 near SCARB2 was found to be significantly associated with Parkinson's disease (PD) in populations of European ancestry. Herein, we conducted a case-control study with attempt to further evaluate the association between SNP rs6812193 and PD in a Chinese population from mainland China. rs6812193 was genotyped by PCR-RFLP technique in 449 PD patients and 452 controls in a Chinese population. In our study, we did not detect statistically significant differences between cases and controls in terms of both allele and genotype distribution of the rs6812193 polymorphism (P=0.97 and P=0.77, respectively), even after stratification by age at onset. Our data do not support the association of SNP rs6812193 with PD in Han Chinese of mainland China.

Assessment of substantia nigra echogenicity in German and Filipino populations using a portable ultrasound system

OBJECTIVES

Transcranial sonography of the substantia nigra for diagnosing premotor stages of Parkinson disease has been attracting increasing interest. Standard reference values defining an abnormal increased echogenic size (hyperechogenicity) of the substantia nigra have been established in several populations using high-end stationary ultrasound systems. It is unknown whether a portable ultrasound system can be appropriately used and how the Filipino population would compare with the well-studied white population.

METHODS

We prospectively studied substantia nigra echogenic sizes and third ventricle widths in 71 healthy adult German participants and 30 age- and sex-matched Filipino participants using both a well-established stationary ultrasound system (in the German cohort) and a recently distributed portable ultrasound system (in both ethnic cohorts).

RESULTS

Mean substantia nigra echogenic sizes, cutoff values defining abnormal hyperechogenicity, and intra-rater reliability were similar with both systems and in both ethnic cohorts studied. The Filipino and German participants did not differ with respect to the frequency of insufficient insonation conditions (each 3%) and substantia nigra hyperechogenicity (10% versus 9%; P = .80). However, third ventricle widths were smaller in the Filipino than the German participants (mean ± SD, 1.6 ± 1.1 versus 2.4 ± 1.0 mm; P = .004).

CONCLUSIONS

The frequency of substantia nigra hyperechogenicity appears to be homogeneous in white and Asian populations. Screening for this feature may well be performed with a present-day portable ultrasound system.

Lrrk2 p.Q1111H substitution and Parkinson's disease in Latin America

Mutations in the LRRK2 gene are the most common genetic cause of Parkinson's disease, with frequencies displaying a high degree of population-specificity. Although more than 100 coding substitutions have been identified, only seven have been proven to be highly penetrant pathogenic mutations. Studies however are lacking in non-white populations. Recently, Lrrk2 p.Q1111H (rs78365431) was identified in two affected Hispanic brothers and absent in 386 non-Hispanic white healthy controls. We therefore screened this variant in 1460 individuals (1150 PD patients and 310 healthy controls) from 4 Latin American countries (Peru, Chile, Uruguay and Argentina). In our case-control series from Peru and Chile we observed an increased frequency of Lrrk2 p.Q1111H in patients (7.9%) compared to controls (5.4%) although the difference did not reach significance (OR 1.38; p = 0.10). In addition, the frequency of Lrrk2 p.Q1111H varied greatly between populations and further screening in a set of pure Amerindian and pure Spanish controls suggested that this variant likely originated in an Amerindian population. Further studies in other Latin American populations are warranted to assess its role as a risk factor for Parkinson's disease. Screening in Parkinson's disease patients from under-represented populations will increase our understanding of the role of LRRK2 variants in disease risk worldwide.

Low frequency of common LRRK2 mutations in Mexican patients with Parkinson's disease

Mutations in leucine-rich repeat kinase 2 gene (LRRK2) account for as much as 5-6% of familial Parkinson's disease (PD) and 1-2% of sporadic PD. These mutations represent the most frequent cause of autosomal dominant PD, particularly in certain ethnic groups. In this first report concerning LRRK2 mutations in Mexican-mestizos, we screened 319 consecutive PD patients (186 males; 133 females; mean age at onset: 52.4 years) for LRRK2 mutations in exons 31 and 41 and for the mutation in exon 35, which produces the Y1699C substitution. Three (0.94%) patients, two with sporadic PD and one with familial PD (disease mean age at onset, 53.3 years), were heterozygous for LRRK2 mutations. Of these three, two patients had one of two different mutations in exon 31 (R1441G and R1441H, respectively); the other patient carried the G2019S mutation in exon 41. The Y1699C mutation was absent from this PD sample. Four additional subjects, unaffected relatives of one PD patient with a mutation in LRRK2, were subsequently genetically tested. None of the three LRRK2 mutations identified was present in 200 neurologically healthy Mexican control individuals. These findings have important implications for molecular testing of LRRK2 mutations in Mexican PD patients.

Intonation contrast in Cantonese speakers with hypokinetic dysarthria associated with Parkinson's disease

PURPOSE

Speech produced by individuals with hypokinetic dysarthria associated with Parkinson's disease (PD) is characterized by a number of features including impaired speech prosody. The purpose of this study was to investigate intonation contrasts produced by this group of speakers.

METHOD

Speech materials with a question-statement contrast were collected from 14 Cantonese speakers with PD. Twenty listeners then classified the productions as either questions or statements. Acoustic analyses of F0, duration, and intensity were conducted to determine which acoustic cues distinguished the production of questions from statements, and which cues appeared to be exploited by listeners in identifying intonational contrasts.

RESULTS

The results show that listeners identified statements with a high degree of accuracy, but the accuracy of question identification ranged from 0.56% to 96% across the 14 speakers. The speakers with PD used similar acoustic cues as nondysarthric Cantonese speakers to mark the question-statement contrast, although the contrasts were not observed in all speakers. Listeners mainly used F0 cues at the final syllable for intonation identification.

CONCLUSION

These data contribute to the researchers' understanding of intonation marking in speakers with PD, with specific application to the production and perception of intonation in a lexical tone language.

The prevalence of Parkinson's disease in an Arab population, Wadi Ara, Israel

BACKGROUND

The prevalence of Parkinson's disease varies among ethnic and geographic groups around the world, being very low in China and high in Argentina. While the main etiology of the disease has yet to be determined, environmental, occupational and genetic factors seem to play important roles.

OBJECTIVES

To estimate the prevalence of PD in an Arab Muslim population in Israel, using the drug tracer approach.

METHODS

We studied a Muslim Arab population living in a well-defined geographic area in Israel, with the majority located in two towns and two large villages. Of the approximately 115,000 residents, about 38% are under the age of 15 and 7.75% are older than 65. Drug tracer methodology was applied in this study. All those who were on anti-PD medication were identified and examined by a neurologist to confirm the diagnosis.

RESULTS

The overall crude prevalence of PD in this population was low, 43.24/100,000, while the prevalence in the age group above 65 years was 477.32/100,000. Below this age, the prevalence was very low, 12.29/100,000. PD prevalence was higher in males than in females (ratio 1.17); 63% of male patients smoked cigarettes. The prevalence was found to be twice as high among the residents of rural areas, where most inhabitants work in agriculture.

CONCLUSIONS

The prevalence of PD among the Arab population in Israel is considered low and comparable to that reported in other Arab countries.

A large-scale genetic association study to evaluate the contribution of Omi/HtrA2 (PARK13) to Parkinson's disease

High-profile studies have provided conflicting results regarding the involvement of the Omi/HtrA2 gene in Parkinson's disease (PD) susceptibility. Therefore, we performed a large-scale analysis of the association of common Omi/HtrA2 variants in the Genetic Epidemiology of Parkinson's disease (GEO-PD) consortium. GEO-PD sites provided clinical and genetic data including affection status, gender, ethnicity, age at study, age at examination (all subjects); age at onset and family history of PD (patients). Genotyping was performed for the five most informative SNPs spanning the Omi/HtrA2 gene in approximately 2-3 kb intervals (rs10779958, rs2231250, rs72470544, rs1183739, rs2241028). Fixed as well as random effect models were used to provide summary risk estimates of Omi/HtrA2 variants. The 20 GEO-PD sites provided data for 6378 cases and 8880 controls. No overall significant associations for the five Omi/HtrA2 SNPs and PD were observed using either fixed effect or random effect models. The summary odds ratios ranged between 0.98 and 1.08 and the estimates of between-study heterogeneity were not large (non-significant Q statistics for all 5 SNPs; I(2) estimates 0-28%). Trends for association were seen for participants of Scandinavian descent for rs2241028 (OR 1.41, p=0.04) and for rs1183739 for age at examination (cut-off 65 years; OR 1.17, p=0.02), but these would not be significant after adjusting for multiple comparisons and their Bayes factors were only modest. This largest association study performed to define the role of any gene in the pathogenesis of Parkinson's disease revealed no overall strong association of Omi/HtrA2 variants with PD in populations worldwide.

[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.