R. Pavanni

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 Parkinsons 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 G2019S LRRK2 mutation is uncommon in an Asian cohort of Parkinson's disease patients

A common heterozygous leucine-rich repeat kinase 2 (LRRK2) mutation 6055G > A transition (G2019S) accounts for about 3-7% of familial Parkinsons disease (PD) and 1-1.6% sporadic PD in a number of European populations. To determine the prevalence of the G1019S mutation in our Asian population, we conducted genetic analysis of this mutation in 1000 PD and healthy controls. The G2019S mutation was not detected in any of our study subjects. The prevalence of G2019S mutation is rare (< 0.1%) in our population, suggesting that occurrence of this mutation may vary amongst different ethnic races. This has important clinical implication when implementing guidelines for genetic testing.

Alpha-synuclein haplotypes implicated in risk of Parkinson’s disease

The authors examined four- and six-loci haplotype constructs (from five single nucleotide polymorphisms and three microsatellite regions) of the alpha-synuclein gene in patients with Parkinson’s disease (PD) and controls in an ethnic Chinese population. Logistic regression analysis demonstrated an association of NACP-Rep1 (p = 0.002) and L478 (p < 0.0001) with risk of PD after correction for the effects of age, sex, and the other polymorphic loci. Specific four-loci and six-loci haplotypes were significantly associated with an increased or decreased risk of PD.

PINK1 mutations in sporadic early‐onset Parkinson's disease

Pathogenic PINK1 mutations have been described in PARK6‐linked Parkinsons disease (PD) patients of Asian origin. However, data on the frequency of PINK1 mutations in sporadic early‐onset Parkinsons disease (EOPD) Asian patients are lacking. The objectives of this study were to report the frequency of PINK1 mutations of sporadic EOPD in an Asian cohort comprising of ethnic Chinese, Malays, and Indians, and to highlight a PINK1‐positive patient who presented with restless legs symptoms. Eighty consecutive sporadic EOPD patients from the movement disorder clinics of two major tertiary institutions in the country were included. We performed sequence analysis of all the coding and exon–intron junctions of the PINK1 using specific primer sets. In addition, we genotyped polymorphisms detected from the analysis in a group of sporadic PD patients and controls. Three different mutations (two homozygous nonsense and one heterozygous missense) in the putative kinase domain were found in three patients, giving a 3.7% frequency of PINK1 mutations in our EOPD cohort. All the mutations were absent in 200 healthy controls. One patient with a novel homozygous nonsense PINK1 mutation presented unusually with restless legs symptoms. Separately, analysis of the frequency of four PINK1 polymorphisms in a group of sporadic PD and controls did not reveal any significant differences. We highlight a 3.7% frequency of PINK1 mutations in an Asian cohort (ethnic Chinese, Malay, and Indian) of EOPD. The phenotypic spectrum associated with PINK1‐positive patients may be wider than previously reported. Polymorphisms of PINK1 do not appear to modulate risk of PD in our population.

Analysis of LRRK2 functional domains in nondominant Parkinson disease.

A comprehensive sequence analysis of 29 exons that code for the functional domains of LRRK2 in 160 nondominant Parkinson disease (PD) patients was performed. Novel variant screening in a further 470 sporadic PD patients and 630 controls revealed two novel variants (R1067Q and IVS33 + 6 T>A), which are likely to be pathogenic in five patients. One patient presented initially with a typical essential tremor phenotype, expanding the phenotypic spectrum of LRRK2 mutations.

Fragile X premutation alleles in SCA, ET, and parkinsonism in an Asian cohort

Among 367 subjects, the authors analyzed 167 patients with essential tremor, sporadic progressive cerebellar ataxia, multiple-system atrophy, and atypical parkinsonism and 200 healthy control subjects for FMR1 premutation alleles. None of the subjects carried alleles within the premutation range. These findings suggest that in the absence of other supportive clinical or imaging features, the cost-effectiveness of routine fragile X tremor/ataxia syndrome screening in this Asian cohort with movement disorders was low.

Analysis of GWAS-linked loci in Parkinson disease reaffirms PARK16 as a susceptibility locus

Objective: A genome-wide association study (GWAS) in the Japanese population identified 2 new Parkinson disease (PD) susceptibility loci on 1q32 (PARK16) (OMIM 613164) and BST1. We analyzed single nucleotide polymorphism (SNPs) located at the GWAS-linked loci (PARK16, PARK8, PARK1, and BST1) in a Chinese population and also conducted a meta-analysis in Asians by pooling 2 independent replication studies from Japan. Methods: We conducted an analysis of 13 SNPs associated with PD GWAS-linked loci in 2 case-control cohorts comprised of 1,349 ethnic Chinese subjects. Results: PARK16, PARK8, and PARK1 loci but not BST1 were found to be associated with PD. PARK16 SNPs were associated with a decreased risk while PARK1 and PARK8 SNPs were associated with an increased risk of PD. A pooled analysis of our Chinese cohorts and 2 Japanese replication cohorts involving 1,366 subjects with PD and 16,669 controls revealed robust association with these 3 loci and also BST1. There was a trend toward a stronger protective effect of SNPs at the PARK16 locus in sporadic PD compared to familial cases and in older compared to younger subjects. Conclusions: Our study reaffirms the role of GWAS-linked loci in PD in Asian subjects and the strength of association is similar between Chinese and Japanese subjects. Efforts to elucidate the associated gene within PARK16 locus are warranted.

Analysis of 14 LRRK2 mutations in Parkinson's plus syndromes and late-onset Parkinson's disease

The pleomorphic pathology of postmortem LRRK2‐positive patients and the frequent association with late‐onset Parkinsons disease (LOPD) symptoms suggest that LRRK2 mutations may play a role in Parkinsons Plus disorders and LOPD. Published studies primarily focus on the common G2019S mutation. Analysis of a spectrum of LRRK2 mutations in Parkinsons Plus disorders has yet to be reported. We investigated 14 leucine‐rich repeat kinase 2 (LRRK2) mutations in a cohort of Parkinsons Plus disorders and LOPD. A total of 458 patients with progressive supranuclear palsy (PSP), multiple system atrophy (MSA), corticobasal ganglionic degeneration (CBGD), atypical Parkinsonism (AP), and LOPD were screened for 14 mutations that span exons 19 to 41 of the LRRK2 gene. Among the LOPD cases, 1 patient was found to harbor the R1441C mutation. He presented with typical features of PD at age of 58 years old and responded well to levodopa. We did not detect any of the 14 mutations in PSP, MSA, CBGD, and AP patients. We highlight the first case of LRRK2 R1441C mutation in late onset sporadic PD of non‐European ancestry. Furthermore, extensive mutational screen found LRRK2 mutations to be rare among patients who presented with PSP, MSA, CBGD, and AP.

Is hypertension associated with hemifacial spasm

Hemifacial spasm (HFS) is characterized by intermittent twitching of the muscles innervated by the ipsilateral facial nerve.1 Reports of normalization of blood pressure after vascular decompression in hypertensive patients suggest an association of hypertension with brainstem compression.2 A recent multicenter case–control study demonstrated a significantly higher prevalence of hypertension in white patients with HFS.3 The cause and effect of hypertension in HFS might have an impact on the management of HFS. Using case–control methodology, we examined the association of hypertension and HFS among HFS patients in our population and investigated differences in neurovascular contact (NVC) of the root exit zone (REZ) of the seventh cranial nerve in HFS patients with and without hypertension using high-resolution MRI/MR angiography (MRA). Methods. Consecutive HFS patients (117) from the movement disorder clinic and controls (245) without HFS seen in the general outpatient clinic for conditions unrelated to hypertension were included in the study. For every HFS patient, we selected two controls of similar age, sex, ethnicity, and body mass index (BMI). A history of hypertension was not an exclusion criterion. All HFS patients were offered brain MRI/MRA as part of the evaluation. We defined hypertension by World Health Organization classification criteria,4 which we also used in our recent National Health Survey (http//www.moh.gov.sg): systolic pressure 140 mm Hg or diastolic pressure 90 mm Hg, or both. Blood pressure was measured using standardized methods3-5 over two to three visits for a period of months as recommended for the diagnosis of hypertension. The imaging comprised three-dimensional time-offlight MRA (TR35, TE6, FA20, 1 nex,192 512 matrix, 1.0-mm partitions) and constructive interference at steady-state sequences (TR12, TE6, FA70, 2 nex, 230 512 matrix, 0.7-mm partitions). A neuroradiologist blinded to the side of HFS interpreted the images. NVC of the seventh cranial nerve was defined as the presence of vascular contact, compression of its REZ, or both. The following data of HFS patients and controls were analyzed: age, sex, duration of HFS, side of HFS, duration of hypertension, associated medical conditions, and MRI/MRA findings. The history of the duration of hemifacial spasm and a history of hypertension were obtained from the patients and corroborated by family members or physicians. Results. The demographics of the study subjects are shown in the table. The mean duration of HFS was 3.9 3.7 (standard deviation [SD]) years (range 0.1 to 20). The mean duration of hypertension in HFS patients and controls was 7.1 8.3 (SD) years (range 0.1 to 30) and 7.2 6.5 (SD) years (range 0.5 to 40). There was no significant difference between the prevalence of hypertension in HFS and controls (see the table). We used multivariate logistic regression analysis with step-wise variable selection for the following variables for both patients and controls: hypertension, diabetes mellitus, renal impairment, ischemic heart disease, cerebrovascular accident, smoking, and alcohol. We did not find significant confounding variables for the association of hypertension with HFS. MRI/MRA was performed in 96 (82.0%) of the 117 HFS patients. NVC of seventh cranial nerve on the side of HFS was found in 90 (93.8%) of patients who underwent MRI/MRA examination. Fourteen of them (14.6%) had NVC bilaterally. The most common offending vessel was the anterior inferior cerebellar artery. The actual vessel could not be identified in 2 of 96 (2.1%). NVC of the seventh cranial nerve was found in 39 of 41 (95.1%) and 51 of 55 (92.7%) in hypertensive and nonhypertensive HFS. Discussion. Although the prevalence of hypertension in HFS was higher (42.7% versus 39.1%) compared to controls matched for age, sex, and BMI, the difference was not significant (see the table). Stratifying the patients and controls by age groups also did not reveal any significant difference of hypertension between the two groups. Similar conclusions were found when we compared the findings with our population controls (National Health Population Survey, 1998). A large difference in the hypertension prevalence (40% to 50%) between HFS and controls would be necessary to impact our clinical management of the majority of HFS patients. As there was probably a selection bias for the more severe HFS patients in the movement disorder clinic, a higher than expected prevalence of hypertension in HFS would have been observed. However, our findings suggested that hypertension was not a major risk factor for HFS in our population. Unlike previous studies,3,5,6 we used controls matched for age, sex, and BMI, and our patients were investigated with highresolution MRI/MRA techniques highly sensitive for NVC in HFS. The availability of population control data based on similar methodology has helped to increase the power of analysis. We did not have imaging data in our study controls and could not investigate the association of NVC of the REZ of the seventh nerve or the ventrolateral medulla with hypertension. However, in a previous MRI/MRA study, NVC of the seventh cranial nerve in our control population was 25%,7 much lower than the 95.1% and 92.7% in our hypertensive and nonhypertensive HFS patients in this study. This suggests that NVC of the REZ of the seventh cranial nerve is unlikely to be associated with hypertension. Our results suggest that there may be etiologic differences among the races. It is possible that anatomic differences in the

Genetic analysis of Nurr1 haplotypes in Parkinson's disease

Nurr1 gene plays an important role in the development of the mesencephalic dopaminergic system. Genetic variability of Nurr1 gene may be associated with risk of Parkinsons disease (PD). We found three polymorphic loci (c.-2922(C)2-3, IVS6+18insG and EX8+657 (9-10CA)) of the Nurr1 gene in our PD patients and a novel intron 7+33 C-->T variant in one PD patient. We proceeded to perform a haplotype analysis in a case control study. A total of 202 PD patients (mean age 65.04+/-9.44 years, 55.4% men) and 202 age, gender and race matched controls (mean age 64.33+/-10.12 years, 54.0% men) were studied. The intron 7+33 C-->T variant was present in only one of the PD patients (0.5%) but in none of the controls. The Nurr1 mRNA levels in the lymphocytes did not significantly differ between the affected patient and controls. We found complete linkage disequilibrium between c.-2922(C)2-3 and IVS6+18insG polymorphic loci (D=0.25). Analysis of the three loci haplotype frequencies did not demonstrate any significant difference between PD and controls. There were also no significant differences in the haplotype frequencies between young and late onset PD patients. In conclusion, we demonstrated a large common haplotype block spanning the Nurr1 gene in our population. The intron 7+33 C-->T variant most likely represents either a non-functional mutation or a rare polymorphism in our study population. Our study suggests that Nurr1 variability is unlikely to play a major role in the majority of our PD patients.