Polarized structured illumination microscopy using polarization gratings for optical sectioning: publisher's note.

This publisher's note contains corrections to Appl. Opt.62, 7373 (2023)APOPAI0003-693510.1364/AO.502290.

Polarized structured illumination microscopy using polarization gratings for optical sectioning.

In this investigation, we describe polarized structured illumination microscopy based on polarization gratings to generate a stable polarized illumination pattern in an extensive area. The visibility of the illumination pattern is immediately calculated by using a polarizing pixelated camera, and the 3D surface profile of the specimen can be successfully reconstructed. Moreover, a polarization grating pair was used to reasonably eliminate the unexpected pattern caused by the polarization grating itself. To experimentally characterize the system performance, a step height standard specimen was measured. Moreover, the axial response for the visibility of the illumination pattern was discussed with the consideration of the spectral bandwidth of the source and the spatial coherence of incident light.

Association between non-cystic fibrosis bronchiectasis and the risk of incident dementia: A nationwide cohort study.

BACKGROUND: Chronic lung diseases, such as chronic obstructive pulmonary disease or asthma, are associated with an increased risk of dementia. However, few data are available regarding the risk of dementia in individuals with bronchiectasis. OBJECTIVES: To explore the association between bronchiectasis and the risk of incident dementia using a longitudinal population-based cohort. METHODS: A total of 4,068,560 adults older than 50 years without previous dementia were enrolled from the Korean National Health Insurance Service database in 2009. They were followed up until the date of the diagnosis of dementia or December 31, 2020. The study exposure was the diagnosis of bronchiectasis, and the primary outcome was incident dementia comprising Alzheimer's disease and vascular dementia. RESULTS: During the median follow-up duration of 9.3 years, the incidence of all-cause dementia was 1.6-fold higher in individuals with bronchiectasis than in those without bronchiectasis (15.0 vs. 9.3/1000 person-years, p < .001). In the multivariable Cox regression analysis, the risk of all dementia was significantly higher in individuals with bronchiectasis than in those without bronchiectasis (adjusted hazard ratio [aHR] 1.09, 95% confidence interval [CI] 1.04-1.14). In a subgroup analysis by dementia type, individuals with bronchiectasis had an increased risk of Alzheimer's disease compared to those without bronchiectasis (aHR 1.07, 95% CI 1.01-1.12); the risk of vascular dementia did not significantly differ between the two groups (aHR 1.05, 95% CI 0.90-1.21). CONCLUSION: Bronchiectasis was associated with an increased risk of dementia, especially Alzheimer's disease.

Tuberculosis and Risk of Ischemic Stroke: A Nationwide Cohort Study.

BACKGROUND: Conflicting results exist regarding the risk of ischemic stroke in tuberculosis survivors. We aimed to estimate the risk of ischemic stroke using a nationwide population-based retrospective cohort. METHODS: We gathered data from the Korean National Health Insurance Service on tuberculosis survivors and 1:1 age- and sex-matched non-tuberculosis cases. Eligible participants were followed up from 1 year after tuberculosis diagnosis to the date of ischemic stroke event, date of death, or until the end of the study period (December 31, 2018), whichever came first. Cox proportional hazard regression and stratified analyses were performed to identify any related factors. RESULTS: During follow-up periods of 3.8 years for patients with tuberculosis and matched non-tuberculosis cases, 1.3% of patients with tuberculosis (941/72 863) and 1.0% of matched non-tuberculosis cases (707/72 863) developed ischemic stroke. The overall risk of ischemic stroke was higher in tuberculosis patients (adjusted hazard ratio: 1.22 [95% CI, 1.10-1.36]) compared with the matched non-tuberculosis cases. A stratified analysis showed that patients with tuberculosis had increased risk of ischemic stroke regardless of age, sex, smoking status, alcohol consumption, physical activity, body mass index, and Charlson Comorbidity Index score. CONCLUSIONS: Tuberculosis survivors had a higher risk of ischemic stroke than their matched non-tuberculosis cases. The results of this study suggest that tuberculosis is a crucial infectious factor associated with increased incidence of ischemic stroke.

Polarized imaging interpreter for simultaneous clocking metrology of multiple objects.

A polarized imaging interpreter to simultaneously measure rotational angles of multiple objects is proposed and experimentally verified. Based on the multiplexed optical configuration using a polarization pixelated camera, the proposed sensor has the unique feature to precisely monitor the standard and the non-standard clocking motions in static or dynamic applications at once.

A case report of adult-onset Alexander disease clinically presenting as Parkinson's disease: is the comorbidity associated with genetic susceptibility?

BACKGROUND: Alexander disease is a rare neurological disease characterized by progressive spastic quadriparesis and bulbar palsy. Moreover, certain patients with adult-onset Alexander disease were often misdiagnosed as other neurodegenerative disorders. CASE PRESENTATION: Herein, we report an adult a 58-year-old woman presented with typical parkinsonism with good levodopa-responsiveness. The patient's dopamine transporter scanning showed significant striatal depletion, while her brain magnetic resonance imaging revealed bilateral tadpole shape of medulla oblongata and bilateral high signal intensity at both cerebellar dentate nuclei in T2-weighted images, suggesting the possibility of a genetic disorder beyond Parkinson's disease. The patient's genetic test resulted in known pathogenic glial fibrillary acidic protein variant, indicating Alexander disease. CONCLUSION: This unique case highlights genetically diagnosed Alexander disease may present with clinical Parkinson's disease.

Characteristics of Sodium Polyacrylate/Nano-Sized Carbon Hydrogel for Biomedical Patch.

Conductive hydrogels were prepared for biomedical patch in order to improve the electrical conductivity. Sodium polyacrylate and nano-sized carbon were mixed and fabricated by aqueous solution gelation process in various contents of nano-sized carbon with 0.1, 0.5, 1.0 and 2.0 wt%. Sodium polyacrylate/nano-sized carbon conductive hydrogels were investigated by molecular structure, surface morphology and electrical conductivity. The conductivity of the hydrogel/nano-sized carbon conductive hydrogel proved to be 10% higher than conductive hydrogel without nano-sized carbon. However, it was founded that conductive hydrogels with nano-sized carbon content from 0.5 up to 2.0 wt% were remarkably decreased. This may be due to the non-uniform distribution of nano-sized carbon, resulting from agglomerates of nano-sized carbon. The developed hydrogel is intended for use in the medical and cosmetic fields that is applicable to supply micro-current from device to human body.

Effect of the Manganese Phosphate Solution with Additive Agent of Tartaric Acid.

In this study, the correlation between morphology and friction of manganese phosphate coating layer with additive agent of tartaric acid by 2, 4, 6 g were investigated. The microstructure and morphology of the coatings were studied by scanning electron microscopy (SEM), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS) and atomic force microscopic (AFM). Potentiodynamic polarization test was carried out in order to evaluate the corrosion protection properties of manganese phosphate coating in 3.5 wt.% NaCl solution. Also, the tribology property of manganese phophate coating was tested by ball-on disk. In the results of EDS analysis, coating layer consists of elements such as Mn, P, Fe, O, and C. XRD showed that (Mn, Fe)5H2(PO4)4·4H2O in manganese phosphate coating layer was formed by the chemical reaction between manganese phosphate and elements in SM45C alloy. The corrosion resistance of manganese phosphate coating with additive agent was superior than the one without additive agent. Also, in the Fe amount in sludge, manganese phosphate coating layer with additive agent was observed to be considerably decreased.

Differential Progression of Midbrain Atrophy in Parkinsonism: Longitudinal MRI Study.

AIMS: To elucidate different patterns of progression of midbrain atrophy in patients with Richardson's syndrome (RS), progressive supranuclear palsy-parkinsonism (PSP-P), and Parkinson's disease (PD) using magnetic resonance imaging (MRI)-based visual rating indexes. METHODS: We recruited 12 patients with PSP-RS, 12 with PSP-P, and 23 with PD for whom MRIs had been followed up for at least 2 years (mean ± SD, 4.9 ± 1.6 years) after the initial MRI. MRI-based visual rating indexes were used to estimate midbrain atrophy, including the ratio of the pontine to midbrain tegmental areas (P/M ratio) on a midsagittal image, the length between the interpeduncular fossa and the center of the cerebral aqueduct at the midmammillary-body level (MTEGM) on axial images, and the morning glory sign. RESULTS: Initially, there were no differences in MRI-based visual rating indexes between PSP-P and PD, while PSP-RS showed a higher P/M ratio and lower MTEGM compared with PSP-P and PD. In PD, the P/M ratio and MTEGM remained stable with disease progression. However, the extent of changes between initial and follow-up indexes was similarly greater for both PSP-RS and PSP-P than for PD. Finally, PSP-P showed a higher P/M ratio and lower MTEGM compared with PD in the follow-up, while PSP-RS still exhibited the most profound changes. CONCLUSIONS: Midbrain atrophy progresses differentially in patients with PSP-RS, PSP-P, and PD. Longitudinal measurements of midbrain atrophy using MRI-based visual rating indexes can help distinguish patients with PSP-P from those with PSP-RS and PD.

Levodopa dose maintenance or reduction in patients with Parkinson's disease transitioning to levodopa/carbidopa/entacapone.

BACKGROUND: Levodopa bioavailability is enhanced by adding entacapone. However, the optimal dose of levodopa while transitioning to levodopa/carbidopa/entacapone (LCE) in Parkinson's disease (PD) during the wearing-off period is unclear. AIMS: The relative therapeutic efficacy and safety of different doses of levodopa were assessed when transitioning to the LCE combination for optimizing combined levodopa therapy. MATERIALS AND METHODS: A randomized, multicenter, double-arm, open-label study was conducted in Korea. The patients were randomly assigned to either a maintained levodopa dose (Group 1, n = 66) or a reduced levodopa dose by 15-25% (Group 2, n = 41). Treatment efficacy, safety, and tolerability were assessed during an 8-week treatment period. RESULTS: Eighty of the 107 (74.8%) participants completed the study (Group 1, n = 50; Group 2, n = 30). The patients' global impression of a change in scores indicated significant benefits of maintaining the levodopa dose (Group 1) compared to reducing the dose (Group 2). Although changes in the unified Parkinson's disease rating scale (UPDRS) scores, Hoehn and Yahr (H and Y) stages, and duration of ON, OFF and dyskinesia were not statistically different between the groups, an increased ON time and a reduced OFF time occurred in both the groups after LCE administration. Twenty-four participants (26.7%) experienced adverse events and 15 of them did not complete the study in the safety population (Group 1, n = 57; Group 2, n = 38). Significant drug-related withdrawal caused troublesome dyskinesia and aggravation of Parkinsonism in both Group 1 and Group 2, respectively. CONCLUSIONS: Direct transitioning to LCE, without levodopa dose reduction, is recommended in Asian patients with PD and wearing-off.

Lifestyle factors associated with symptoms suggestive of restless legs syndrome in Korean adolescents.

OBJECTIVE: Restless legs syndrome (RLS) is a common sleep disorder among adolescents. This study aimed to investigate the lifestyle factors and sleep disturbances associated with the symptoms suggestive of RLS in Korean adolescents. METHODS: In this cross-sectional study, we investigated a total of 25,789 adolescents (mean age, 15.8 ± 1.7 years; male, 48.5 %). The presence of symptoms suggestive of RLS was assessed with a single question about RLS in the Global Sleep Assessment Questionnaire. We performed multiple logistic regression analysis to estimate the odds ratios (ORs) and 95 % confidence intervals (CIs) of lifestyle factors and sleep disturbances that were independently associated with adolescent RLS. RESULTS: The prevalence of RLS-suggestive symptoms was 5.1 % among adolescents. After adjustment, lifestyle factors associated with symptoms suggestive of RLS were occasional alcohol consumption (OR, 1.245; 95 % CI, 1.006-1.540) and proneness to Internet addiction (OR, 1.027; 95 % CI, 1.021-1.033). Bedtime behaviors associated with RLS-suggestive symptoms were sleeping with a doll or pet (OR, 1.194; 95 % CI, 1.032-1.381) and sleeping with a TV or radio on (OR, 1.366; 95 % CI, 1.156-1.614). Male sex, frequent snoring and witnessed apnea, perceived sleep insufficiency, excessive daytime sleepiness were also associated with RLS-suggestive symptoms in adolescents. CONCLUSIONS: Adolescents with symptoms suggestive of RLS were associated with different lifestyle factors compared to adults with RLS. Further research is needed to determine the clinical implications of lifestyle factors in adolescent RLS.

Risk of dementia in survivors of active tuberculosis in Korea: A nationwide cohort study.

BACKGROUND: Concern has been growing regarding post-tuberculosis (TB) morbidities, including neurologic and vascular comorbidities. However, the association between post-TB status and the risk of dementia has been evaluated in only few studies. Therefore, in the present study, the risk of dementia was investigated in a nationwide population-based cohort. METHODS: Using the Korean National Health Insurance Service (KNHIS) database, this study included TB survivors (n = 50,182) and matched controls (n = 50,182) for age, sex, and year of index date. The risk of dementia was estimated using Cox proportional hazards regression, and stratified analyses for related factors were performed. RESULTS: During a mean 3.5 years of follow-up, the incidence of dementia was 9.32 for Alzheimer disease and 1.17 for vascular dementia per 1000 person-years for TB survivors and 7.21 and 0.67, respectively, for matched controls. The overall risk of Alzheimer disease was 1.11 (95% confidence interval (CI) 1.03-1.20)-fold higher in TB survivors than in matched controls. For vascular dementia, 1.48 (95% CI 1.16-1.89)-fold higher risk was found in TB survivors than in matched controls. The strength of the association between TB and dementia was higher in CNS TB (aHR 1.76, 95% CI 1.18 -2.64) than non-CNS TB (aHR 1.11, 95% CI 1.05-1.19) compared to controls, especially for patients with vascular dementia (3.33, 95% CI 1.06-10.49). CONCLUSION: TB survivors had a significantly higher risk of dementia than the general population.

Tailoring tokamak error fields to control plasma instabilities and transport.

A tokamak relies on the axisymmetric magnetic fields to confine fusion plasmas and aims to deliver sustainable and clean energy. However, misalignments arise inevitably in the tokamak construction, leading to small asymmetries in the magnetic field known as error fields (EFs). The EFs have been a major concern in the tokamak approaches because small EFs, even less than 0.1%, can drive a plasma disruption. Meanwhile, the EFs in the tokamak can be favorably used for controlling plasma instabilities, such as edge-localized modes (ELMs). Here we show an optimization that tailors the EFs to maintain an edge 3D response for ELM control with a minimized core 3D response to avoid plasma disruption and unnecessary confinement degradation. We design and demonstrate such an edge-localized 3D response in the KSTAR facility, benefiting from its unique flexibility to change many degrees of freedom in the 3D coil space for the various fusion plasma regimes. This favorable control of the tokamak EF represents a notable advance for designing intrinsically 3D tokamaks to optimize stability and confinement for next-step fusion reactors.

Numerical verification of bounce-harmonic resonances in neoclassical toroidal viscosity for tokamaks.

This Letter presents the first numerical verification for the bounce-harmonic (BH) resonance phenomena of the neoclassical transport in a tokamak perturbed by nonaxisymmetric magnetic fields. The BH resonances were predicted by analytic theories of neoclassical toroidal viscosity (NTV), as the parallel and perpendicular drift motions can be resonant and result in a great enhancement of the radial momentum transport. A new drift-kinetic δf guiding-center particle code, POCA, clearly verified that the perpendicular drift motions can reduce the transport by phase-mixing, but in the BH resonances the motions can form closed orbits and particles radially drift out fast. The POCA calculations on resulting NTV torque are largely consistent with analytic calculations, and show that the BH resonances can easily dominate the NTV torque when a plasma rotates in the perturbed tokamak and therefore, is a critical physics for predicting the rotation and stability in the International Thermonuclear Experimental Reactor.

Whole exome sequencing and clinical investigation of young onset dystonia: What can we learn?

BACKGROUND: Dystonia is a heterogeneous movement disorder involving various genetic backgrounds, and the implication of whole exome sequencing (WES) has yet to be clearly elucidated. In this study, we performed WES in Korean patients with young-onset dystonia. METHODS: We recruited patients with young-onset dystonia based on the new MDS dystonia classification at Samsung Medical Centre from 2015 to 2019. We excluded subjects diagnosed by single gene tests (GCH1, TOR1A, PANK2, PRRT2, and SGCE) or levodopa trials and subjects with focal or possible secondary dystonia. We performed WES in all enrolled subjects and confirmed the results with Sanger sequencing. RESULTS: Of the 43 patients, we detected 11 disease-causing variants, classified as either pathogenic or likely pathogenic, in 9 patients (20.9%). Generalized dystonia, infancy-childhood-onset dystonia, and other combined neurologic manifestations were related with PV/LPV. When we retrospectively reviewed the patients with PV/LPV, brain imaging was diagnostic in 3 subjects (HTRA1, SCL20A, and WDR45), clinical characteristics of paroxysmal presentation were observed in 2 (ADCY5 and ATP1A3), and microcephaly was noted in 1 patient (KMT2B). CONCLUSION: Clinical exome sequencing is helpful for the diagnosis of dystonia, especially for that with infancy-childhood onset, and generalized dystonia with other neurologic manifestations. Additionally, careful evaluations and examinations could provide information for selecting candidates for genetic testing.

Effect of Helicobacter pylori Eradication on Body Weight: A Multicenter Propensity Score-matched Analysis in Korea.

Background/Aims: There is growing interest in whether Helicobacter pylori eradication (HPE) can affect body weight. Methods: Data from 5 universities between January 2013 and December 2019 were analyzed retrospectively. H. pylori-positive subjects who had body weight measurements taken at least twice at intervals of 3 months or longer were included. Using propensity score (PS)-matched data, changes in body mass index (BMI) and the lipid profile after HPE were compared with the non-HPE group. Results: Among 363 eligible patients, 131 HPE patients were PS-matched to 131 non-HPE patients. The median intervals between the measurements were 610 (range, 154-1250) days and 606 (range, 154-1648) days in the HPE and non-HPE groups, respectively. In both groups, the mean BMI increased (from 24.5 kg/m2 to 24.7 kg/m2 in the HPE group, and from 24.4 kg/m2 to 24.5 kg/m2 in the non-HPE group). The 2 groups did not show significantly different changes (P = 0.921). In the lowest baseline BMI quartile, the BMI increased after HPE by 1.23 (standard deviation [SD], 3.72) kg/m2 (P = 0.060), and the non-HPE group showed a decreased BMI at the time of follow-up (by -0.24 [SD, 5.25] kg/m2; P = 0.937) (between-group P = 0.214). Triglyceride levels increased after HPE (mean: 135 [SD, 78] to 153 [SD, 100] mg/dL; between-group P = 0.053). Conclusion: The overall BMI change was not significantly different between the HPE and non-HPE groups, but patients with low BMI showed a tendency to gain weight after HPE. Triglyceride levels increased after HPE with marginal significance.

Association between Self-Perceived Periodic Limb Movement during Sleep and Excessive Daytime Sleepiness Depend on Restless Leg Symptoms in Korean Adolescents.

Although periodic limb movement during sleep (PLMS) and restless legs syndrome (RLS) are common in children and adolescents, they are relatively overlooked as a target of treatment. PLMS has been evaluated as having a lower clinical significance than RLS. This study examined the relationship of socio-behavioral factors of PLMS in Korean adolescents and checked whether PLMS is associated with excessive daytime sleepiness (EDS), depending on whether restless legs symptoms accompany it. In a cross-sectional study, 25,789 adolescents between 12 and 18 years of age (15.76 ± 1.73 years; female 51.49%) were evaluated using an online survey. Various self-report questionnaires were used to assess PLMS and RLS symptoms, EDS, sleep habits, and various socio-behavioral factors. The prevalence of self-perceived PLMS and restless legs symptoms were 903 (3.50%) and 1311 (5.08%), respectively. Of the 1311 participants, 399 had self-perceived PLMS. The odds ratios (ORs) for self-perceived PLMS in participants with restless legs symptoms were: males (OR = 1.528; 95% CI: 1.145-2.040), usually/always experienced apnea apnea (OR, 3.006; 95% CI, 1.954-4.624), increased proneness to Internet addiction (OR = 1.013; 95% CI: 1.001-1.025), sometimes/often consuming coffee (OR = 1.312; 95% CI: 1.015-1.695), EDS (OR = 0.826; 95% CI: 0.488-1.398), and perceived insufficient sleep (OR = 1.143; 95% CI: 0.835-1.565). The male gender, witness apnea, consuming coffee, and being prone to Internet addiction were identified as factors significantly associated with self-perceived PLMS in participants with restless legs symptoms. However, EDS and insufficient sleep were associated with self-perceived PLMS in the absence of restless legs symptoms.

Validation of the Korean version of the composite autonomic symptom scale 31 in patients with Parkinson's disease.

PURPOSE: The composite autonomic symptom scale-31 (COMPASS-31) is a self-rated questionnaire that evaluates diverse autonomic symptoms. In the present study, we developed the Korean version of the COMPASS-31 (K-COMPASS-31) with appropriate translation, and verified its reliability and internal and external validity in patients with Parkinson's disease (PD). METHODS: The original COMPASS-31 was translated independently into Korean by two bilingual neurologists. Test-retest reliability was evaluated at a 2-week interval. We investigated the correlations between the K-COMPASS-31, the scale for outcomes in PD-autonomic (SCOPA-AUT), and the results of an autonomic function test (AFT), respectively. RESULTS: A total of 90 patients with PD (47 females; mean age, 63.4 ± 10.8 years) were enrolled. The K-COMPASS-31 showed excellent test-retest reliability (intra-class correlation coefficient = 0.874, p < 0.001) and internal validity (Cronbach's α-coefficient = 0.878). The COMPASS-31 was positively correlated with SCOPA-AUT (r = 0.609, p < 0.001) and the results of the AFT. CONCLUSIONS: In conclusion, the K-COMPASS-31 showed excellent reliability and validity for the assessment of autonomic symptoms in PD patients. The K-COMPASS-31 is an easy-to-repeat and widely used tool for investigating autonomic dysfunction in various neurologic disorders and enables comparison of autonomic dysfunction among neurologic disorders. We recommend the K-COMPASS-31 as a valid instrument for use in clinical practice for patients with PD.

A stepped-plate bi-frequency source for generating a difference frequency sound with a parametric array.

An ultrasonic radiator is developed to generate a difference frequency sound from two frequencies of ultrasound in air with a parametric array. A design method is proposed for an ultrasonic radiator capable of generating highly directive, high-amplitude ultrasonic sound beams at two different frequencies in air based on a modification of the stepped-plate ultrasonic radiator. The stepped-plate ultrasonic radiator was introduced by Gallego-Juarez et al. [Ultrasonics 16, 267-271 (1978)] in their previous study and can effectively generate highly directive, large-amplitude ultrasonic sounds in air, but only at a single frequency. Because parametric array sources must be able to generate sounds at more than one frequency, a design modification is crucial to the application of a stepped-plate ultrasonic radiator as a parametric array source in air. The aforementioned method was employed to design a parametric radiator for use in air. A prototype of this design was constructed and tested to determine whether it could successfully generate a difference frequency sound with a parametric array. The results confirmed that the proposed single small-area transducer was suitable as a parametric radiator in air.

Clarification of undiagnosed ataxia using whole-exome sequencing with clinical implications.

BACKGROUND: Hereditary cerebellar ataxias exhibit heterogeneous phenotypes and genotypes. To date, advancement of next-generation sequencing technologies have identified many causative genes for ataxia in various population. In this study, whole-exome sequencing (WES) was utilized to explore the genetic cause of ataxia among Korean patients who remained undiagnosed following routine investigation. METHODS: Patients with ataxia were enrolled in this study. We excluded patients with acquired, degenerative, and trinucleotide repeat ataxias, such as spinocerebellar ataxia 1 (SCA1), SCA2, SCA3, SCA6, SCA7, SCA8, SCA17, Dentatorubral-pallidoluysian atrophy, and Friedreich ataxia. WES was performed. After basic filtering based on population databases, we then performed primary filtering to screen for known ataxia-associated genes, followed by expanded filtering customized for individual patients. RESULTS: We enrolled 77 ataxia patients from 68 families. Eighteen families had pathogenic or likely pathogenic variants in 14 different genes, including NEU1, APTX, SPG7, HTRA1, POLG2, SYNE1, CACNA1G, CACNA1A, ITPR1, AHI1, SPG11, ANO10, ATM, and C5orf42, resulting in a diagnostic yield of 26.5%. Hereditary spastic paraplegia was the most common diagnosis. Adult-onset ataxias and those without family history were frequently encountered. Variants of unknown significance were found in 14 (20.6%) families, some of which were highly probable from the clinical perspective. CONCLUSION: Using WES, we explored the molecular etiology of ataxia in patients whom were not diagnosed through routine clinical investigation. This study revealed unexpected rare disorders as well as the known ataxia-associated genes in a Korean population.