Genetic analysis of SCA 27 in ataxia and childhood onset postural tremor.
Explore the source record for details and available documents.
Adolescent↗
Biomedical subjects
Eng-King Tan
Publications and source records attributed to Eng-King Tan.
Impaired motor imagery in patients with essential tremor: a case control study.
Motor imagery (MI), which refers to the process of mental representation of movements, has not been studied in patients with essential tremor (ET). We investigated the presence of impaired MI in ET patients compared with healthy controls. A group of drug-naive and nondemented ET patients and age-matched controls were studied using transcranial magnetic stimulation, while they were specifically instructed to try and imagine themselves performing two motor tasks. The various clinical and electrophysiological variables were evaluated and compared. Repeated measures ANOVA demonstrated a significant difference between ET patients and controls with respect to mean motor-evoked potential (MEP) amplitudes (F(1,38) = 31.92, P < 0.005) during MI. The process of MI effectively facilitated MEP amplitude in controls but not in ET patients, regardless of side of stimulation or motor tasks. We provide evidence to demonstrate impairment of MI in a group of ET patients compared with healthy controls. The basis for this novel finding is unclear, and further studies are warranted to determine whether it is related to cerebellar or motor cortical dysfunction.
Adult↗
Valproate-induced Parkinsonism in epilepsy patients.
We systematically examined 226 epilepsy patients in a tertiary-referral center and found 6 (5.04%) to have valproate-induced Parkinsonism. There was a significantly higher prevalence of patients with Parkinsonism in the group of patients treated with valproate compared to those who were on other antiepileptic drugs (6 [5.04%] of 119 vs. 0 [0%] of 107; chi2 = 5.54; P = 0.025). These six patients had been on valproate for more than 3 years (mean, 75.67 +/- 25.32 months) at an average dose of 750 +/- 273.86 mg/day. The valproate doses were decreased or discontinued with supplementation from another antiepileptic medication. The mean UPDRS motor score significantly improved from 10.67 +/- 5.1 to 4.75 +/- 2.75 (P < 0.05). There was no relapse of seizures. Clinicians working in tertiary-referral centers should have a high index of suspicion for valproate-induced Parkinsonism. Early recognition and switching into another antiepileptic medication may help reduce unnecessary suffering in these patients.
Adult↗
LRRK2 G2019S founder haplotype in the Chinese population.
The G2019S mutation in the LRRK2 (leucine-rich repeat kinase) gene appears very rarely in the Chinese population. Among Chinese subjects who were non-G2019S carriers, we demonstrated the frequency of the LRRK2 G2019S founder haplotype (T-254-A-G-A-154) in Parkinson's disease and controls to be 33% and 30%. This rate is similar to the frequency in European noncarriers, indirectly supporting the association of this haplotype with G2019S carriers. The haplotype is likely to be more ancient than the G2019S mutation because it is also found in a population with a very low carrier rate.
Asian People↗
Persistent hand spasm: movement disorder or seizure?
Dystonia is a movement disorder characterized by involuntary, sustained or repetitive, patterned muscle contractions or spasms, frequently causing squeezing and twisting movements or abnormal postures. Dystonic posturing could be one of the accompanying features of epilepsy. We report an elderly lady with intractable focal seizure who presented with more than a year of persistent hand spasms. The clinical importance of differentiating epilepsy from movement disorders is discussed.
Aged↗
Comparing knowledge and attitudes towards genetic testing in Parkinson's disease in an American and Asian population.
INTRODUCTION: Recent discoveries of disease-causing genes in Parkinson's disease (PD) have generated considerable interest regarding genetic testing in PD. The attitudes toward genetic testing are largely influenced by knowledge and preconceived notions. OBJECTIVE: We investigated the relationship between knowledge of and attitude towards predictive genetic testing of PD in two independent centers in America and Asia involving PD patients and caregivers. METHODS: In a prospective study involving 515 subjects comprising of PD patients and their caregivers in two independent centers in America and Asia, the level of knowledge about genetic testing and patients' attitudes towards such testing were evaluated using a standardized questionnaire. RESULTS: American PD patients had a higher level of knowledge of PD genetics than Asian PD (31.1% vs. 12.3%, p=0.0002). A greater number of American PD patients and caregivers reported a positive attitude towards the potential medical benefits of genetic testing compared to their Asian counterparts (85.4% vs. 42.2%, 92.2% vs. 32.1%, p<0.00005), but a more negative attitude towards potential compromise in getting health and life insurance (43.7% vs. 25.8%, p=0.0002). However, in the Asian cohort, multivariate analysis revealed that a high level of genetics knowledge was associated with a positive attitude response regarding the potential medical benefits of testing (p<0.0005), but a negative attitude towards compromises in healthcare and life insurance, getting a job and starting a family (p<0.0005). These associations were not observed amongst American subjects. CONCLUSIONS: The relationship between level of genetic knowledge and attitude towards potential risks and benefits of predictive genetic testing in PD was distinctly different in two independent, racially and culturally different PD populations and caregivers. These observations have clinical implications in the development of PD genetic counseling programs.
Adult↗
CARD15 variants in patients with sporadic Parkinson's disease.
Recent reports have proven the importance of genetic factors and inflammation in the pathogenesis of sporadic Parkinson's disease (PD). In the current study, the frequency of CARD15/NOD2 gene variants (R702W, G908R, L1007fs), previously associated with Crohn's disease--a common inflammatory bowel disease, have been examined in a group of 308 sporadic PD patients and 220 healthy controls. Significantly higher frequency of total CARD15 variant alleles in PD patients (13.0%) compared to the controls (8.0%, p<0.02) was observed. 24.0% of PD patients carried at least one CARD15 variant allele compared to 15.5% of healthy controls (p<0.02, OR=1.73). The results of the study suggest, that the polymorphism in CARD15/NOD2 gene may be a risk factor for sporadic PD development, and support the concept of inflammatory pathogenesis of PD.
Adult↗
Isolated facial myorhythmia.
Myorhythmia, characterized by relatively rhythmic and regular 1- to 3-Hz muscle contractions, may involve isolated limbs or in combination with other various body regions. Isolated facial myorhythmia is rare. We highlight the clinical and electrophysiologic features of a unique case of isolated facial myorhythmia. Extensive investigations did not reveal any conclusive secondary causes. Dopaminergic dysfunction could be one of the etio-pathologic factors. However, the pathological basis why the facial region was selectively involved in our patient is unclear. Early recognition of the symptoms and signs would facilitate investigations for an underlying cause.
Aged↗
Collaborative analysis of alpha-synuclein gene promoter variability and Parkinson disease.
CONTEXT: Identification and replication of susceptibility genes for Parkinson disease at the population level have been hampered by small studies with potential biases. Alpha-synuclein (SNCA) has been one of the most promising susceptibility genes, but large-scale studies have been lacking. OBJECTIVE: To determine whether allele-length variability in the dinucleotide repeat sequence (REP1) of the SNCA gene promoter is associated with Parkinson disease susceptibility, whether SNCA promoter haplotypes are associated with Parkinson disease, and whether REP1 variability modifies age at onset. DESIGN, SETTING, AND PARTICIPANTS: We performed a collaborative analysis of individual-level data on SNCA REP1 and flanking markers in patients with Parkinson disease and controls. Study site recruitment, data collection, and analyses were performed between April 5, 2004, and December 31, 2005. Eighteen participating sites of a global genetics consortium provided clinical data. Genotyping was performed for SNCA REP1, -770, and -116 markers at individual sites; however, each site also provided 20 DNA samples for regenotyping centrally. MAIN OUTCOME MEASURES: Measures included estimations of Hardy-Weinberg equilibrium in controls; a test of heterogeneity; analyses for association of single variants or haplotypes; and survival analyses for age at onset. RESULTS: Of the 18 sites, 11 met stringent criteria for concordance with Hardy-Weinberg equilibrium and low genotyping error rate. These 11 sites provided complete data for 2692 cases and 2652 controls. There was no heterogeneity across studies (P>.60). The SNCA REP1 alleles differed in frequency for cases and controls (P<.001). Genotypes defined by the 263 base-pair allele were associated with Parkinson disease (odds ratio, 1.43; 95% confidence interval, 1.22-1.69; P<.001 for trend). Multilocus haplotypes differed in frequency for cases and controls (global score statistic, P<.001). Two-loci haplotypes were associated with Parkinson disease only when they included REP1 as one of the loci. However, genotypes defined by REP1 alleles did not modify age at onset (P = .55). CONCLUSION: This large-scale collaborative analysis demonstrates that SNCA REP1 allele-length variability is associated with an increased risk of Parkinson disease.
Adult↗
DYT1 mutations amongst adult primary dystonia patients in Singapore with review of literature comparing East and West.
BACKGROUND: Dystonia is a heterogenous group of movement disorders whose clinical spectrum is very wide. At least 13 different genes and gene loci have been reported. While a 3-bp deletion in the DYT1 gene is the most frequent cause of early limb-onset, generalized dystonia, it has also been found in non-generalized forms of sporadic dystonia. An 18-bp deletion in the DYT1 gene has also been reported. OBJECTIVES: We screened for the 3-bp and 18-bp deletions in the DYT1 gene among our sporadic, adult-onset primary dystonia patients in Singapore. We reviewed the literature to compare the frequency of DYT1 mutation between the East and the West. METHODS: We screened 54 patients with primary dystonia (focal: n=41; segmental: n=11; multifocal: n=1; generalized: n=1) for the deletions in the DYT1 gene. A careful review of all published literature on DYT1 screening among sporadic, non-familial, non-Ashkenazi Jewish patients was done. RESULTS: We did not detect any mutations in the exon 5 of the DYT1 gene in any of our patients. The frequency of DYT1 mutation amongst Asians (1.0%) was comparable to the West (1.56%) (p=NS). CONCLUSIONS: DYT1 mutations are uncommon amongst adult primary dystonia patients in Singapore.
Adult↗
Polymorphism in semaphorin 5A (Sema5A) gene is not a marker of Parkinson's disease risk.
A SNP rs7702187 within the semaphorin 5A gene (Sema5A) has been recently associated with sporadic Parkinson's disease (PD) risk in American Caucasians. In the present study frequencies of rs7702187 was determined in two independent populations involving 427 sporadic PD patients (235 Polish Caucasians and 192 Asians from Singapore) and 412 healthy controls (220 Caucasians and 192 Asians), with the use of PCR-RFLP assay. The frequencies of the minor allele were found to be very similar in PD patients and healthy controls in both populations studied: 0.147 versus 0.143 in Caucasian, and 0.224 versus 0.221 in Asian, respectively. Our research does not confirm the previous observation, as no relationship was found between polymorphism within Sema5A gene and the risk of PD. It can be concluded that rs7702187 SNP in Sema5a gene is not a marker of PD risk in the studied populations.
Adult↗
Primary vs postparalytic hemifacial spasm.
Explore the source record for details and available documents.
Diagnosis, Differential↗
Genetic testing in Parkinson disease: promises and pitfalls.
Explore the source record for details and available documents.
Age of Onset↗
PINK1 mutations in sporadic early-onset Parkinson's disease.
Pathogenic PINK1 mutations have been described in PARK6-linked Parkinson's disease (PD) patients of Asian origin. However, data on the frequency of PINK1 mutations in sporadic early-onset Parkinson's 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.
Adult↗
Movement disorders associated with hyperthyroidism: expanding the phenotype.
Explore the source record for details and available documents.
Autoantibodies↗
Case-control study of UCHL1 S18Y variant in Parkinson's disease.
A recent meta-analysis observed a greater significant inverse association of the ubiquitin carboxy-terminal hydrolase L1 (UCHL1) S18Y variant with Parkinson's disease (PD) for Asian (predominantly Japanese) populations compared with Caucasian populations. We performed an independent case-control study in 335 PD and 341 control subjects with data from a Chinese population to investigate the age-of-onset effect of the UCHL1 variant in PD. The Y/Y and Y/S genotypes were less frequent in the PD young-onset group than in controls and the frequency of the Y alleles was higher in young controls compared to young-onset PD (age at examination <or= 65 years; P = 0.003). Multivariate analysis revealed the Y/Y genotype was significantly lower (P = 0.008) in the young-onset PD (Y/Y vs. S/S: odds ratio [OR]: 0.42; 95% confidence interval [CI]: 0.24, 0.74; S/Y vs. S/S: OR: 0.66, 95% CI: 0.41, 1.08) compared with controls, but this difference was not seen for the late-onset PD. Kaplan-Meier analysis carried out on PD subjects demonstrated that the Y/Y genotype was associated with a later onset of PD than Y/S plus S/S genotypes (P = 0.05). We provided an independent confirmation of the protective effect of the UCHL1 S18Y variant (Y/Y genotype) against PD in young Chinese subjects. Further functional studies of the S18Y variant in both cell and animal models will be of interest.
Adult↗
Case-control study of anxiety symptoms in hemifacial spasm.
In a case-control study, we evaluated symptoms in nine different psychological domains in hemifacial spasm (HFS; using the Symptom Checklist-90R [SCL-90R]) and found the anxiety score to be significantly greater in HFS compared to healthy controls in both the univariate (P = 0.004) and multivariate analysis (adjusted for sex, age, marital status, and educational level; P = 0.002). Similar findings were obtained when comparison was made with an independent group of outpatient controls. Compared to outpatient controls, the HFS patients had a higher mean Hamilton Anxiety Rating Score (HAM-A; 10.0 +/- 8.0 [range, 0 to 28] vs. 5.0 +/- 5.0 [range, 0 to 25]; P = 0.004), and 19.5% had HAM-A score of 18 or above compared to 3.8% in controls (P = 0.02). Among the HFS patients, the mean anxiety score in SCL-90R was significantly higher in those defined with mild to severe anxiety under HAM-A compared to those without anxiety (74.0 +/- 6.0 vs. 48.0 +/- 13.0) (P < 0.0005). There was good correlation of the anxiety score with the HAM-A in HFS patients (r = 0.915; P < 0.0001). HFS patients with anxiety reported significant improvement of their symptoms (mean HAM-A score 19.0 +/- 5.0 vs. 11.0 +/- 6.0; P = 0.001) following appropriate management. As stress and anxiety can aggravate HFS, diagnosis and early management of anxiety symptoms can improve quality of life in these patients.
Adult↗
Restless legs syndrome and Parkinson's disease: is there an etiologic link?
The etiologic link between restless legs syndrome (RLS) and Parkinson's disease (PD) has been debated. Since dopaminergic dysfunction and response to dopaminergic agents are consistent features in RLS and PD, some authors have suggested that these two diseases may share common pathophysiology. However, presently there is not enough evidence to suggest that the actual pathophysiologic mechanism in both diseases is identical. The nigrostriatal dopaminergic system is primarily involved in PD and it is possible that the extrastriatal dopaminergic system may be variably involved in those PD patients with RLS symptoms. Further clinical, imaging, pharmacologic, and genetic studies will be needed to address the many unanswered questions related to the link between RLS and PD.
Dopamine↗