Prevalence of Parkinson disease in Singapore: Chinese vs Malays vs Indians

OBJECTIVE

To investigate the prevalence of Parkinson disease (PD) in Singapore and compare the rates between Singaporean Chinese, Malays, and Indians.

METHODS

A three-phase community-based survey among a disproportionate random sample of 15,000 individuals (9,000 Chinese, 3,000 Malays, 3,000 Indians) aged 50 years and above who live in central Singapore was conducted. In phase 1, trained interviewers conducted a door-to-door survey using a validated 10-question questionnaire. In phase 2, medical specialists examined participants who screened positive to any of the questions. Participants suspected to have PD had their diagnosis confirmed in phase 3 by a movement disorders specialist.

RESULTS

The participation rate was 67% among 22,279 eligible individuals. Forty-six participants with PD were identified of which 16 were newly diagnosed cases. The prevalence rate of PD for those aged 50 and above in Singapore was 0.30% (95% CI: 0.22 to 0.41), age-adjusted to US 1970 census. The prevalence rates increased significantly with age. The age-adjusted prevalence rates among Chinese (0.33%, 95% CI: 0.22 to 0.48), Malays (0.29%, 95% CI: 0.13 to 0.67), and Indians (0.28%, 95% CI: 0.12 to 0.67) were the same (p = 1.0).

CONCLUSIONS

The prevalence of PD in Singapore was comparable to that of Western countries. Race-specific rates were also similar to previously reported rates and similar among the three races. Environmental factors may be more important than racially determined genetic factors in the development of PD.

Genes influencing Parkinson disease onset

A genome screen to identify genes influencing the age at Parkinson disease (PD) onset was completed using 276 families without parkin mutations. Significant evidence of linkage to chromosome 2p near the PARK3 locus (logarithm of odds [lod] = 4.8) was observed. Evidence of linkage was also detected to chromosomes 1q (lod = 3.0) and 8q (lod = 2.6). These data suggest that the genes influencing age at PD onset likely differ from those that contribute to PD susceptibility.

Detection ofParkin(PARK2) andDJ1(PARK7) mutations in early-onset Parkinson disease:Parkinmutation frequency depends on ethnic origin of patients

Mutations in the Parkin (PARK2) and the DJ1 (PARK7) gene cause early-onset Parkinson disease (EOPD). We tested 75 Serbian EOPD patients for mutations in both genes by conventional mutational screening (SSCP/dHPLC/sequencing) to detect small sequence alterations and by gene dosage studies (quantitative PCR) to reveal deletions or multiplications of one or more exons. A compound heterozygous Parkin mutation (exon deletion and point mutation; [c.836_972del]+[c.1411C>T]; +1 is first nucleotide of GenBank AB009973.1) was identified in a patient who showed a relatively benign course after a disease onset at 41 years. Another case had a heterozygous exon deletion in DJ1 ([c.253_322del]+[?]) and presented with an age at onset of 45 years and a rapid disease course. In conclusion, Parkin mutations are surprisingly rare in our Serbian EOPD sample, suggesting that the mutation rate depends on the ethnic origin of the patients. Although DJ1 mutations appear to be rare, we confirm their role in EOPD and demonstrate the importance of gene dosage studies.

Prevalence of Parkinson's disease in a Chinese population

BACKGROUND

Ethnic differences in the prevalence of Parkinson's disease have been observed, but may be due to differences in screening instruments and diagnostic criteria.

AIMS

To compare the prevalence of Parkinson's disease in Hong Kong Chinese and Australians in Sydney.

METHODS

A door-to-door community survey in the Hong Kong Chinese population was carried out using a two-staged procedure (screening questionnaire followed by physical examination), which had been validated for use in the community in a survey among Australians, to determine the prevalence in Chinese and to compare with that in Australians.

RESULTS

A total of 1080 households were contacted, the non-response rate was 27%. The prevalence among those aged 55 years in the community and above was 0.5%, and 0.186% for the overall population assuming no subjects were below 55 years. These figures are lower than the 3.6% for Australians, aged >55 years.

CONCLUSION

There appears to be a difference in prevalence of Parkinson's disease between Hong Kong Chinese and Australians in Sydney. Such differences may be due to documented differences in prevalence of genetic polymorphisms associated with Parkinson's disease between Chinese and Australians, or to differences in environmental factors.

Comparison of Environmental and Genetic Factors for Parkinson’s Disease between Chinese and Caucasians

This review paper compares the differences in prevalence, and environmental and genetic risk factors for Parkinson's disease between Chinese and Caucasian subjects. Comparison of age-specific prevalence between Chinese people and Caucasians suggests that the prevalence is lower in the Chinese (at least in the past), although the prevalence rate in China appears to be rising. Distinctions in environmental risk factors and genetic factors are discussed. The difference in prevalence may be due to distinctions in environmental and genetic risk factors as well as the complex interaction between these environmental and genetic factors, although discrepancies in methodology for prevalence surveys can also be an explanation.

Dose-dependent protective effect of coffee, tea, and smoking in Parkinson's disease: a study in ethnic Chinese

INTRODUCTION

Few studies have examined the relationship of coffee and tea in Parkinson's disease (PD). The potential protective effect of coffee intake and risk of PD has not been studied in a Chinese population. There is a high prevalence of caffeine takers among Chinese in our population.

OBJECTIVE

We undertook a case control study to examine the relationship between coffee and tea drinking, cigarette smoking, and other enviromental factors and risk of PD among ethnic Chinese in our population.

METHODS AND RESULTS

300 PD and 500 population controls were initially screened. Two hundred case control pairs matched for age, gender, and race were finally included in the analysis. Univariate analysis revealed significant association of PD with coffee drinking (p<0.0005), tea drinking (p=0.019), alcohol drinking (p=0.001), cigarette smoking (p<0.0005), and exposure to heavy metals (p=0.006). Conditional logistic regression analysis demonstrated that amount of coffee drunk (OR 0.787, 95%CI 0.664-0.932, p=0.006), amount of tea drunk (OR 0.724, 95%CI 0.559-0.937, p=0.014), number of cigarettes smoked (OR 0.384, 95%CI 0.204-0.722, p=0.003), history of heavy metal and toxin exposure (OR 11.837, 95%CI 1.075-130.366, p=0.044), and heart disease (OR 5.518, 95%CI 1.377-22.116, p=0.016) to be significant factors associated with PD. One unit of coffee and tea (3 cups/day for 10 years) would lead to a 22% and 28% risk reduction of PD. One unit of cigarette smoke (3 packs/day for 10 years) reduced the risk of PD by 62%.

CONCLUSIONS

We demonstrated a dose-dependent protective effect of PD in coffee and tea drinkers and smokers in an ethnic Chinese population. A history of exposure to heavy metals increased the risk of PD, supporting the multifactorial etiologies of the disease.

The role of pathogenic DJ-1 mutations in Parkinson's disease

Mutations in DJ-1 (PARK7) have been reported in two consanguineous families with young-onset Parkinson's disease (YOPD). This study aims to confirm the presence of pathogenic DJ-1 mutations and determine their contribution in young-onset and more typical later onset Parkinson's disease (PD). The entire open reading frame of the DJ-1 gene was screened by direct sequencing in 185 unrelated YOPD patients and a separate cohort of 190 pathologically proven cases of PD. Ethnically matched controls were screened for all mutations identified. We report a low frequency of pathogenic DJ-1 mutations in our cohort of patients. One homozygous missense mutation and one heterozygous mutation were found in two YOPD samples. In addition, several variants were found in the coding sequence of the gene, which are likely to represent polymorphisms. In one case, the polymorphism was population specific. The reported 14Kbp deletion was not found in any of our samples or controls. We confirm the presence of pathogenic DJ-1 mutations in YOPD and estimate their frequency at approximately 1%. No mutations were found in our cohort of later onset sporadic pathologically confirmed cases, suggesting that DJ-1 mutations may only rarely contribute to the cause of this more typical sporadic form of the disease.

The Saitohin 'Q7R' polymorphism and tau haplotype in multi-ethnic Alzheimer disease and Parkinson's disease cohorts

In a multi-ethnic cohort we analyzed the Saitohin (STH) gene 'Q7R' polymorphism in 200 late-onset Alzheimer's disease cases (LOAD), 60 Parkinson's disease cases with dementia (PDD), 84 Parkinson's disease cases without dementia and 458 controls. We found no significant differences in genotype or allele frequencies when LOAD or PD cases were compared to controls. Ethnic differences in STH genotype frequencies for cases and controls were observed and these were statistically significant (cases n=344, P<0.03; controls n=458, P<0.001). We also observed a trend in non-Hispanic white PDD cases with the STH 'QQ' (Tau H1/H1) genotype increased (76%) compared to PD cases without dementia (61.7%) and controls (56.6%); however, this difference was not statistically significant (PDD vs. controls OR 2.1; 95% CI: 0.8-5.8, P=0.2).

Lower risk of Parkinson's disease in an admixed population of European and Indian origins

We studied whether the occurrence of Parkinson's disease (PD) in the Anglo-Indians, an admixed population of European and Asian Indian origin, differs from Indians living in the same environment. Epidemiological studies show considerably higher prevalence of PD amongst white compared to non-white populations. Normal Indians contain a approximately 40% lower number of melanized nigral neurons compared to Caucasians from the UK. Anglo-Indians are an admixed population of European and Indian origin. We used the UK Parkinson's Disease Society Brain Bank clinical diagnostic criteria (steps 1 and 2) to diagnose PD in 84 of 493 residents (Indians, 409; Anglo-Indians, 84) living in elderly homes in Bangalore, India. Of these 84, 80 were Indians (19.5%) and 4 were Anglo-Indians (4.8%). Occurrence of PD is nearly five times higher amongst Indians compared to the Anglo-Indians (odds ratio, 3.9; 95% confidence interval, 1.3-12.9). We conclude that an admixture population of European and Indian origins, rather than averaging, might result in reduced occurrences of PD. Hence, studying an admixed population could provide crucial insights into understanding genetic mechanisms in the etiopathogenesis of PD.

Incidence of Parkinson's disease: variation by age, gender, and race/ethnicity

The goal of this study was to estimate the incidence of Parkinson's disease by age, gender, and ethnicity. Newly diagnosed Parkinson's disease cases in 1994-1995 were identified among members of the Kaiser Permanente Medical Care Program of Northern California, a large health maintenance organization. Each case met modified standardized criteria/Hughes diagnostic criteria as applied by a movement disorder specialist. Incidence rates per 100,000 person-years were calculated using the Kaiser Permanente membership information as the denominator and adjusted for age and/or gender using the direct method of standardization. A total of 588 newly diagnosed (incident) cases of Parkinson's disease were identified, which gave an overall annualized age- and gender-adjusted incidence rate of 13.4 per 100,000 (95% confidence interval (CI): 11.4, 15.5). The incidence rapidly increased over the age of 60 years, with only 4% of the cases being under the age of 50 years. The rate for men (19.0 per 100,000, 95% CI: 16.1, 21.8) was 91% higher than that for women (9.9 per 100,000, 95% CI: 7.6, 12.2). The age- and gender-adjusted rate per 100,000 was highest among Hispanics (16.6, 95% CI: 12.0, 21.3), followed by non-Hispanic Whites (13.6, 95% CI: 11.5, 15.7), Asians (11.3, 95% CI: 7.2, 15.3), and Blacks (10.2, 95% CI: 6.4, 14.0). These data suggest that the incidence of Parkinson's disease varies by race/ethnicity.

Strong association between N-acetyltransferase 2 genotype and PD in Hong Kong Chinese

BACKGROUND

The slow acetylator genotype for N-acetyltransferase 2 (NAT2 genotype) may be associated with PD in white subjects and the genotype is common in both white and Chinese populations. Whether there is a relationship between NAT2 genotype and PD in Chinese subjects is not known.

OBJECTIVE

To investigate the association between the slow acetylator genotype for N-acetyltransferase 2 and PD in a Chinese population.

METHODS

The authors obtained DNA samples and documented sex, age, and smoking history in 99 Chinese patients with PD and in 126 control subjects from two major Hong Kong hospitals. PCR-restriction fragment length polymorphism was used to identify M1, M2, and M3 mutant polymorphisms of the slow acetylator genotype for N-acetyltransferase 2. Logistic regression analyses were carried out to investigate the relationships between the different variables and PD.

RESULTS

The frequency of the slow acetylator genotype for N-acetyltransferase 2 in the PD group was significantly higher than that of the control group (68.7% vs 28.6%) with an OR of 5.53 (95% CI 3.08 to 9.92) after adjusting for age, sex, and smoking history. In a subgroup analysis smoking had no modifying effect on the association between genotype and PD.

CONCLUSIONS

There is a significant association between PD and the slow acetylator genotype for N-acetyltransferase 2 in Hong Kong Chinese. The OR found is among the highest reported so far in all susceptibility gene studies for PD in both Chinese and white subjects and provides evidence for a possible functional relationship between NAT2 slow acetylator genotype and PD in both racial groups.

Female preponderance of Parkinson's disease in Japan

A male preponderance of Parkinson's disease (PD) has been reported in European countries and the USA. To verify this issue in Japanese patients with PD, we examined the age- and gender-specific prevalence of PD in Yamagata Prefecture (population 1,244,040), Japan. The prevalence of PD was 61.3/100,000 men and 91.0/100,000 women, showing that women were significantly more affected by PD than men (p < 0.001). Contrary to the findings in Europe and the USA, the results indicate a female preponderance of PD among the Japanese population.

Case-Control study of the extended tau gene haplotype in Parkinson's disease

We investigated the association of Parkinson's disease with tau gene haplotypes. In a sample of 319 unrelated Parkinson's disease patients and 196 control subjects, we observed an increased risk of Parkinson's disease for persons with the H1/H1 genotype (odds ratio = 1.5; 95% confidence interval: 0.98-2.23); however, the finding was not statistically significant. The results remained similar after adjusting for the possible misclassification of progressive supranuclear palsy patients as Parkinson's disease, but became statistically significant after restricting the analysis to nondemented subjects.

Risk factors of Parkinson's disease in Indian patients

Epidemiological data on risk factors of Parkinson's disease (PD) are not available from India. In a case control study, we investigated environmental and genetic risk factors in the etiology of idiopathic Parkinson's disease. Three hundred seventy-seven patients of Parkinson disease (301 men, 76 women, mean+/-SD age 56.78+/-11.08 years) and equal number of age matched (+/-3 years) neurological controls (271 men, 106 women, mean+/-SD age 56.62+/-11.17 years) were included in the study. Conditional logistic regression model was used to determine the risk factors of PD. We found that male gender, family history of Parkinson's disease, past history of depression of up to 10-year duration and well water drinking of more than 10-year duration were significantly associated with occurrence of Parkinson's disease, whereas tobacco smoking of up to 20-year duration and exposure to pets had protective effect. However, tobacco smoking of more than 20-year duration, well water drinking of up to 10-year duration, vegetarian dietary habit, occupation involving physical exertion, rural living, farming, exposure to insecticides, herbicides, rodenticides, alcohol intake and family history of neurodegenerative diseases had no significant correlation with occurrence of PD in the patient population studied. Results of our study support the hypothesis of multifactorial etiology of PD with environmental factors acting on a genetically susceptible host.

A polymorphic variation of serine to tyrosine at codon 18 in the ubiquitin C-terminal hydrolase-L1 gene is associated with a reduced risk of sporadic Parkinson's disease in a Japanese population

Recent studies suggest that ubiquitin C-terminal hydrolase-L1 (UCH-L1), a neuronal deubiquitinating enzyme, represents a candidate gene responsible for either the development of familial Parkinson's disease (PD) or the protection against sporadic PD in Caucasian populations, although these findings are not fully verified in non-Caucasian populations. To determine an association of the variations in the UCH-L1 gene with development of sporadic PD in a Japanese population, a Ser18Tyr polymorphism and an Ile93Met mutation were studied by PCR-RFLP analysis in 74 Japanese patients with sporadic PD and 155 age-matched non-PD controls. The frequency of 18Tyr allele was significantly lower in PD patients than the controls (38.5% vs. 53.5%) (chi(2)=9.064, p=0.0026; the odds ratio=1.84, 95% confident interval=1.23-2.74). Furthermore, the frequency of 18Tyr/Tyr homozygotes was significantly lower in PD patients than the controls (14.9% vs. 33.5%), compared with that of two other genotypes combined (chi(2)=8.767, p=0.0031; the odds ratio=0.35, 95% confident interval=0.27-0.45). The Ile93Met substitution was not detected in any Japanese subjects examined. These results indicate that the presence of 18Tyr allele and 18Tyr/Tyr homozygosity in the UCH-L1 gene is associated with a reduced risk for development of sporadic PD in a Japanese population, supporting the previous observations on sporadic PD in Caucasian populations.

CYP2D6*4 polymorphism is not associated with Parkinson's disease and has no protective role against Alzheimer's disease in the Korean population

CYP2D6*4 polymorphism is reported to be associated with Parkinson's disease (PD) and to have protective role against Alzheimer's disease (AD). Such findings are not extensively studied in the Oriental population, especially Koreans. The effects of CYP2D6*4 polymorphism on AD and PD were investigated by polymerase chain reaction-restriction fragment length polymorphism in Korean subjects. Heterozygous mutant allele was found in four of 93 patients with PD, 0 of 32 patients with AD and one of 121 control subjects (59 stroke, 59 normal controls and four other psychiatric disorders), but no homozygous mutant allele was found. There were no statistically significant differences between the AD group and controls, and between the PD group and controls. In conclusion, we suggest that CYP2D6*4 polymorphism does not confer susceptibility to PD in the Korean population. Also, due to such a rare occurrence of the CYP2D6*4 polymorphism, we can not confirm the protective role of the polymorphism against AD in the Korean population.

Mitochondrial myopathy, parkinsonism, and multiple mtDNA deletions in a Sephardic Jewish family

The authors describe a family of Sephardic Jews with progressive external ophthalmoparesis, skeletal muscle weakness, and parkinsonism. Autosomal recessive inheritance was suggested by many consanguineous marriages, although a dominant disorder could not be excluded. No linkage to known progressive external ophthalmoparesis locus was found. The presence of cytochrome c oxidase-negative ragged-red fibers, biochemically reduced respiratory chain complexes, and multiple mitochondrial DNA deletions in muscle biopsies from four patients suggested a new mitochondrial disorder of intergenomic communication.

Polymorphisms of the parkin gene in sporadic Parkinson's disease among Chinese in Taiwan

The role of genetics in Parkinson's disease (PD), previously controversial, is now documented by several studies. A major breakthrough has been the discovery of two single-gene defects in familial PD. A single base pair change at position 209 from G to A (G209A) in the fourth exon of the alpha-synuclein gene has been identified in cases of autosomal dominant familial PD. Mutations in the Parkin gene can induce autosomal recessive juvenile parkinsonism. A polymorphism of R/W366 in the Parkin gene was found to be associated with a protective factor for sporadic PD. We surveyed the polymorphisms of the Parkin gene, including S/N167, R/W366 and V/L380, in 92 cases of sporadic PD and 98 nonaffected individuals in Taiwanese Chinese. The allele frequencies of these polymorphisms are not significantly different between PD and nonaffected controls. We conclude that polymorphisms of the Parkin gene, S/N167, R/W366, V/L380, are not genetic factors for sporadic PD among Chinese in Taiwan.

No mutation of G209A in the alpha-synuclein gene in sporadic Parkinson's disease among Taiwan Chinese

The role of genetics in Parkinson's disease (PD), previously controversial, is now supported by several studies. A major breakthrough has been the discovery of a single gene defect in familial Parkinson's disease. A single base pair change at position 209 from G to A (G209A) in the fourth exon of the alpha-synuclein gene has been identified in cases of familial PD. We looked for this mutation in 65 cases of sporadic PD in Taiwan Chinese patients but found none of these patients with this mutation. We conclude that mutation of G209A in the alpha-synuclein gene plays no role in sporadic PD among Taiwan Chinese.

Atypical parkinsonism in Afro-Caribbean and Indian origin immigrants to the UK

This article reviews evidence for the occurrence of atypical parkinsonism in Afro-Caribbean and Indian ethnic minority subjects living in western countries, particularly the UK. Current information on the frequency, pattern, and prevalence of Parkinson's disease and parkinsonism in these communities is unclear and controversial. While several workers have suggested that there is a low prevalence of Parkinson's disease in populations of African origin, other workers have suggested a higher prevalence of Parkinson's disease in African Americans. Furthermore, little information is available in relation to the pattern of parkinsonism in these subjects. A recent phenomenologic study of parkinsonism in the French West Indies by Caparros-Lefebvre and colleagues has indicated a significantly increased frequency of atypical parkinsonism in local non-white subjects. Since 1995, we have been studying the pattern and frequency of parkinsonism in Afro-Caribbean and Indian (originating from the Indian subcontinent) patients living in the UK, with London serving as the coordinating center. Our results indicate that there is a three- to fourfold increase in the frequency of occurrence of sporadic atypical parkinsonism characterized by levodopa hyporesponsiveness, bradykinesia-dominant disease, and early cognitive dysfunction in these patients even after exclusion of patients with clinically probable multiple system atrophy, progressive supranuclear palsy, and Lewy body dementia. These findings are similar to observations made in the French West Indies. Ongoing studies in India suggest that atypical parkinsonism also affects local patients, and the pattern of parkinsonism tends to differ from Afro-Caribbean subjects in the UK. Studies are currently underway to unravel the mechanism of increased frequency of atypical parkinsonism in these ethnic groups and include genetic studies addressing polymorphisms of enzymes metabolizing levodopa, dietary neurotoxin screen and functional imaging studies of the striatum using positron emission tomography. Furthermore, the contribution of diabetes mellitus and hypertension, commonly seen in these ethnic groups, is also being examined.

Absence of G209A and G88C mutations in the alpha-synuclein gene of Parkinson's disease in a Chinese population

A G209A mutation in the alpha-synuclein gene was recently discovered in a large Italian kindred and three unrelated Greek kindreds with autosomal dominant Parkinson's disease (PD). Subsequently, another mutation in the gene (G88C) was also identified in a German family with autosomal PD. These results indicate that the alpha-synuclein gene may have an important role in the pathogenesis of PD. This study was designed to screen the existence of both mutations of the alpha-synuclein gene among 100 Chinese patients with PD, including 80 with sporadic and 20 with familial PD. Results showed that none of our patients, both sporadic and familial PD, had either of the two mutations of this gene. We therefore conclude that although of great interest, these two mutations are not relevant for the pathogenesis of PD in a Han Chinese population.

Cytochrome P4502D6 (debrisoquine 4-hydroxylase) and Parkinson's disease in Chinese and Caucasians

Four polymorphic sites (C/T188, C/T2938, G/C4268, G/A1934) in the cytochrome P4502D6 (debrisoquine 4-hydroxylase) gene were investigated for their association with sporadic Parkinson's disease (PD). Three mutant alleles (C/T188, C/T2938 and G/C4268) result in amino acid changes which could alter the substrate specificity or alter its ability to metabolize their substrates; the fourth (G/A1934) causes a loss of enzyme activity. The study was carried out in two ethnically homogenous populations: Chinese (123 PD patients, 124 controls); and Caucasian (95 PD patients, 62 controls). Haplotype status, which took into account amino acid changes at three polymorphic sites, was deduced from genotyping results in order to investigate whether substrate specificity was important rather than loss of enzyme activity. There was no gender difference in the distribution of the alleles in either race. There was, however, significant association among the three polymorphic sites (C/T188, C/T2938, G/C4268) in both ethnic groups. T/T188:C/C2938:C/C4268 is the most common genotype in the Chinese population, in contrast to C/C188:C/T2938:C/G4268 (followed by C/C188:C/C2938:G/G4268) in Caucasians. All 69 of the sub-group of Chinese patients tested were homozygous for the wild-type allele at the G/A1934 polymorphic site. Neither the CYP2D6 allele nor haplotype was associated with PD in either ethnic group.