Genetic Modifiers of Age at Onset for Amyotrophic Lateral Sclerosis: A Genome-Wide Association Study.

OBJECTIVE: Age at onset (AAO) is an essential clinical feature associated with disease progression and mortality in amyotrophic lateral sclerosis (ALS). Identification of genetic variants and environmental risk factors influencing AAO of ALS could help better understand the disease's biological mechanism and provide clinical guidance. However, most genetic studies focused on the risk of ALS, while the genetic background of AAO is less explored. This study aimed to identify genetic and environmental determinants for AAO of ALS. METHODS: We performed a genome-wide association analysis using a Cox proportional hazards model on AAO of ALS in 10,068 patients. We further conducted colocalization analysis and in-vitro functional exploration for the target variants, as well as Mendelian randomization analysis to identify risk factors influencing AAO of ALS. RESULTS: The total heritability of AAO of ALS was ~0.16 (standard error [SE] = 0.03). One novel locus rs2046243 (CTIF) was significantly associated with earlier AAO by ~1.29 years (p = 1.68E-08, beta = 0.10, SE = 0.02). Functional exploration suggested this variant was associated with increased expression of CTIF in multiple tissues including the brain. Colocalization analysis detected a colocalization signal at the locus between AAO of ALS and expression of CTIF. Causal inference indicated higher education level was associated with later AAO. INTERPRETATION: These findings improve the current knowledge of the genetic and environmental etiology of AAO of ALS, and provide a novel target CTIF for further research on ALS pathogenesis and potential therapeutic options to delay the disease onset. ANN NEUROL 2023;94:933-941.

Mutation screening of SPTLC1 and SPTLC2 in amyotrophic lateral sclerosis.

BACKGROUND: Recently, several rare variants of SPTLC1 were identified as disease cause for juvenile amyotrophic lateral sclerosis (ALS) by disrupting the normal homeostatic regulation of serine palmitoyltransferase (SPT). However, further exploration of the rare variants in large cohorts was still necessary. Meanwhile, SPTLC2 plays a similar role as SPTLC1 in the SPT function. METHODS: To explore the genetic role of SPTLC1 and SPTLC2 in ALS, we analyzed the rare protein-coding variants in 2011 patients with ALS and 3298 controls from the Chinese population with whole exome sequencing. Fisher's exact test was performed between each variant and disease risk, while at gene level over-representation of rare variants in patients was examined with optimized sequence kernel association test (SKAT-O). RESULTS: Totally 33 rare variants with minor allele frequency < 0.01 were identified, including 17 in SPTLC1 and 16 in SPTLC2. One adult-onset patient carried the variant p.E406K (SPTLC1) which was reported in previous study. Additionally, three adult-onset patients carried variants in the same amino acids as the variants identified in previous studies (p.Y509C, p.S331T, and p.R239Q in SPTLC1). At gene level, rare variants of SPTLC1 and STPLC2 were not enriched in patients. CONCLUSION: These results broadened the variant spectrum of SPTLC1 and SPTLC2 in ALS, and paved the way for future research. Further replication was still needed to explore the genetic role of SPTLC1 in ALS.

Motor progression marker for newly diagnosed drug-naïve patients with Parkinson's disease: A resting-state functional MRI study.

The effective early prediction of clinical outcomes of Parkinson's disease (PD) is of great significance in the implementation of appropriate interventions. We aimed to propose a method based on the use of baseline resting-state functional characteristics (i.e., fractional amplitude of low-frequency fluctuations, fALFF) to predict motor progression in PD patients. Resting-state functional magnetic resonance imaging was performed on 48 newly-diagnosed drug-naïve PD patients and 27 age- and sex- matched healthy controls (HCs). Two PD subgroups were defined with different annual increase of Unified PD Rating Scale Part III motor scores. Least absolute shrinkage and selection operator regression analysis was performed to explore the baseline region-functional indicators for PD discrimination as well as the predictors for future motor deficits. Two significant models composed of baseline fALFF values from cerebral subregions were proposed. The classification model that distinguished PD patients from HCs (area under the curve [AUC] = 0.897) showed the most significant imaging characteristics in the putamen and precentral gyrus. The other prediction model that evaluated the degree of future deterioration of motor symptoms in PD patients (AUC = 0.916) showed the most significant imaging characteristics in the superior occipital gyrus and caudate nucleus. Furthermore, the increased regional function in bilateral caudate nuclei was correlated with the lower annual increase in motor deficits in all PD patients. The caudate nucleus might be the core region responsible for future motor deficits in newly-diagnosed PD patients, which may aid the development of disease progression preventive strategies in clinical practice.

Longitudinal evolution of sleep disturbances in early multiple system atrophy: a 2-year prospective cohort study.

BACKGROUND: The progression of sleep disturbances remains unclear in patients with early multiple system atrophy (MSA). We aimed to explore the frequency, severity, and coexistence of 2-year longitudinal changes of sleep disturbances including REM sleep behavior disorder (RBD), excessive daytime sleepiness (EDS), and Parkinson's disease-related sleep problems (PD-SP) in early MSA. METHODS: MSA patients with a disease duration < 3 years were enrolled to complete a 2-year follow-up visit. Sleep disturbances including RBD, EDS, and PD-SP were assessed using the RBD Screening Questionnaire, Epworth sleepiness scale, and PD sleep scale-2, respectively. RESULTS: A total of 220 patients with MSA enrolled in the study and 90 patients completed the 2-year follow-up visit. The score of all three sleep disturbances significantly increased over the 2-year follow-up in MSA and MSA with the predominant parkinsonism group (all p < 0.05). The frequency of PD-SP (from 14.5 to 26.7%) and EDS (from 17.7 to 37.8%) was progressively increased (all p < 0.05) except for RBD (from 51.8 to 65.6%, p = 0.152) over the 2-year follow-up in MSA. The frequency of coexistence of two or three sleep disturbances also increased over time. The most common sleep disturbance was RBD, followed by EDS and PD-SP over the 2-year follow-up. CONCLUSIONS: The present study demonstrated that the frequency of different types of sleep disturbances progressively increased except for RBD and the coexistence of two or three sleep disturbances became more common over time in early MSA. Our study suggested that the assessment and management of sleep disturbances should begin early in MSA.

Plasma glial fibrillary acidic protein as a biomarker of disease progression in Parkinson's disease: a prospective cohort study.

BACKGROUND: Reactive astrogliosis has been demonstrated to have a role in Parkinson's disease (PD); however, astrocyte-specific plasma glial fibrillary acidic protein (GFAP)'s correlation with PD progression remains unknown. We aimed to determine whether plasma GFAP can monitor and predict PD progression. METHODS: A total of 184 patients with PD and 95 healthy controls (HCs) were included in this prospective cohort study and followed-up for 5 years. Plasma GFAP, amyloid-beta (Aß), p-tau181, and neurofilament light chain (NfL) were measured at baseline and at 1- and 2-year follow-ups. Motor and non-motor symptoms, activities of daily living, global cognitive function, executive function, and disease stage were evaluated using the Unified Parkinson's Disease Rating Scale (UPDRS) part III, UPDRS-I, UPDRS-II, Montreal Cognitive Assessment (MoCA), Frontal Assessment Battery (FAB), and Hoehn and Yahr (H&Y) scales at each visit, respectively. RESULTS: Plasma GFAP levels were higher in patients with PD (mean [SD]: 69.80 [36.18], pg/mL) compared to HCs (mean [SD]: 57.89 [23.54], pg/mL). Higher levels of GFAP were observed in female and older PD patients. The adjusted linear mixed-effects models showed that plasma GFAP levels were significantly associated with UPDRS-I scores (ß: 0.006, 95% CI [0.001-0.011], p = 0.027). Higher baseline plasma GFAP correlated with faster increase in UPDRS-I (ß: 0.237, 95% CI [0.055-0.419], p = 0.011) and UPDRS-III (ß: 0.676, 95% CI [0.023-1.330], p = 0.043) scores and H&Y stage (ß: 0.098, 95% CI [0.047-0.149], p < 0.001) and faster decrease in MoCA (ß: - 0.501, 95% CI [- 0.768 to - 0.234], p < 0.001) and FAB scores (ß: - 0.358, 95% CI [- 0.587 to - 0.129], p = 0.002). Higher baseline plasma GFAP predicted a more rapid progression to postural instability (hazard ratio: 1.009, 95% CI [1.001-1.017], p = 0.033). CONCLUSIONS: Plasma GFAP might be a potential biomarker for monitoring and predicting disease progression in PD.

Cross-Ethnic Variant Screening and Burden Analysis of PTPA in Parkinson's Disease.

BACKGROUND: Recently, homozygous variants in PTPA were identified as the disease cause for two pedigrees with early-onset parkinsonism and intellectual disability. Although the initial link between PTPA and parkinsonism has been established, further replication was still necessary. OBJECTIVES: To evaluate the genetic role of PTPA in Parkinson's disease (PD). METHODS: We analyzed rare variants of PTPA in cohorts of Asian and European ancestries (Ncase = 2743, Ncontrol = 8177) with whole-exome sequencing, and further explored the functional effect of the target variant. RESULTS: One patient with early-onset PD from a consanguineous family carried the homozygous variant p.Met329Val, while her parents and elder sister with heterozygous p.Met329Val were healthy. This patient developed minor cognitive decline within 1 year, with a Montreal Cognitive Assessment (MoCA) score dropping from 28 to 25. Functional exploration with overexpression studies suggested that this variant was associated with decreased protein phosphatase 2A (PTPA) protein level by affecting protein stability, but not mRNA expression. CONCLUSIONS: These results have broadened the mutation spectrum of PTPA, and paved the way for further research into the role of PTPA in PD. © 2023 International Parkinson and Movement Disorder Society.

Lack of association of TP73 rare variants with amyotrophic lateral sclerosis in a Chinese cohort.

BACKGROUND: Recently, several rare variants of TP73 were identified as potential disease cause for amyotrophic lateral sclerosis (ALS) in the European population. However, further replication was still necessary, especially in cohorts with different ethnic backgrounds. METHODS: To explore the genetic role of TP73 in ALS in the Asian population, we analyzed the rare protein-coding variants in 2011 patients with ALS and 3298 controls with whole-exome sequencing. Fisher's exact test was performed between each variant and disease risk, while at gene level over-representation of rare variants in patients was examined with optimized sequence kernel association test. RESULTS: Totally 24 rare variants with minor allele frequency < 0.01 were identified, among which nine were absent in controls. One variant p.P335T was previously reported, and another three variants were in the same amino acids as the variants reported in previous studies (p.R36Q, p.R414Q, p.R78C). At gene level, rare variants of TP73 were not enriched in patients. CONCLUSIONS: Our findings did not support the genetic role of TP73 in ALS in the Chinese population. Replication of specific variants identified in patients from different cohorts might provide additional insight. The current results also broadened the mutation spectrum of TP73 and paved the way for further research.

TBK1 variants in Chinese patients with amyotrophic lateral sclerosis: Genetic analysis and clinical features.

BACKGROUND AND PURPOSE: Haploinsufficiency of TANK-binding kinase 1 (TBK1) loss-of-function (LoF) variants has been shown to be pathogenic in amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). However, the genetic spectrum of TBK1 and clinical features of ALS patients with TBK1 variants remain largely unknown in Asians. METHODS: Genetic analysis was performed on 2011 Chinese ALS patients. Software was used to predict the deleteriousness of missense variants in TBK1. In addition, PubMed, Embase and Web of Science were searched for related literature. RESULTS: Twenty-six TBK1 variants were identified in 33 of 2011 ALS patients, including six novel LoF variants (0.3%) and 20 rare missense variants, 12 of which were predicted to be deleterious (0.6%). In addition to TBK1 variants, 11 patients had other ALS-related gene variants. Forty-two previous studies found that the frequency of TBK1 variants was 1.81% in ALS/FTD patients. The frequency of TBK1 LoF variants in ALS was 0.5% (Asians 0.4%; Caucasian 0.6%) and that of missense variants was 0.8% (Asians 1.0%; Caucasian 0.8%). ALS patients with TBK1 LoF variants affecting the kinase domain had a significantly younger age of onset than patients carrying LoF variants affecting the coiled coil domains CCD1 and CCD2. FTD has a frequency of 10% in Caucasian ALS patients with TBK1 LoF variants, which was not found in our cohort. CONCLUSION: Our study expanded the genotypic spectrum of ALS patients with TBK1 variants and found that the clinical manifestations of TBK1 carriers are diverse.

Role of genetics in amyotrophic lateral sclerosis: a large cohort study in Chinese mainland population.

BACKGROUND: A large number of new causative and risk genes for amyotrophic lateral sclerosis (ALS) have been identified mostly in patients of European ancestry. In contrast, we know relatively little regarding the genetics of ALS in other ethnic populations. This study aims to provide a comprehensive analysis of the genetics of ALS in an unprecedented large cohort of Chinese mainland population and correlate with the clinical features of rare variants carriers. METHODS: A total of 1587 patients, including 64 familial ALS (FALS) and 1523 sporadic ALS (SALS), and 1866 in-house controls were analysed by whole-exome sequencing and/or testing for G4C2 repeats in C9orf72. Forty-one ALS-associated genes were analysed. FINDINGS: 155 patients, including 26 (40.6%) FALS and 129 (8.5%) SALS, carrying rare pathogenic/likely pathogenic (P/LP) variants of ALS causative genes were identified. SOD1 was the most common mutated gene, followed by C9orf72, FUS, NEK1, TARDBP and TBK1. By burden analysis, rare variants in SOD1, FUS and TARDBP contributed to the collective risk for ALS (p<2.5e-6) at the gene level, but at the allelic level TARDBP p.Gly294Val and FUS p.Arg521Cys and p.Arg521His were the most important single variants causing ALS. Clinically, P/LP variants in TARDBP and C9orf72 were associated with poor prognosis, in FUS linked with younger age of onset, and C9orf72 repeats tended to affect cognition. CONCLUSIONS: Our data provide essential information for understanding the genetic and clinical features of ALS in China and for optimal design of genetic testing and evaluation of disease prognosis.

Genetic analysis of and clinical characteristics associated with ANXA11 variants in a Chinese cohort with amyotrophic lateral sclerosis.

BACKGROUND: Variants in the annexin A11 gene (ANXA11) have been reported to be associated with amyotrophic lateral sclerosis (ALS). These variants may be involved in the pathogenesis of ALS by causing defects in intracellular protein trafficking. However, the genetic spectrum and clinical characteristics of ALS patients with ANXA11 variants are largely unknown. METHODS: Genetic analysis was performed on 1587 Chinese patients with ALS. Eight software packages were used to predict the deleteriousness of missense variants. In addition, we searched PubMed, Embase, and Web of Science for relevant literature and meta-analysed variant frequencies. RESULTS: In our ALS cohort, we identified 20 non-synonymous variants in 29 ALS patients, including one stop-gain, one frameshift, and 18 rare missense variants with seven predicted pathogenic variants. In a literature review of 11 reported studies that included 69 patients, 37 ANXA11 variants were reported, with a frequency of 1.7%, which was similar to that in our cohort (1.8%). Both our cohort and previous reports showed that ANXA11 carriers were more commonly males than females (12/17 vs. 19/31). Patients carrying ANXA11 variants affecting the C-terminal of the protein had earlier disease onset and shorter survival times than those carrying variants affecting the N-terminal. We found a relatively longer median survival time than that previously reported (53.6 months vs. 46.0 months). Additionally, Caucasian ANXA11 carriers were more likely to have cognitive impairment, typically frontotemporal dementia (FTD) than their Asian counterparts (20.0% vs. 14.3%). While more than half of the patients in our cohort had cognitive impairment, none had FTD. CONCLUSION: In our and previously published cases, ALS-associated ANXA11 variants predominantly affected the N- and C-terminal conserved domains. ANXA11 variant carriers are typically male and cognitively impaired. Our study extends the genotypic and phenotypic spectra of ALS patients with ANXA11 variants. Further expansion of the sample size is needed to analyse the clinical and non-motor symptom characteristics of patients and to deepen the understanding of the pathogenesis of ANXA11-associated ALS.

Longitudinal evolution of motor and non-motor symptoms in early-stage multiple system atrophy: a 2-year prospective cohort study.

BACKGROUND: The progression of motor and non-motor symptoms (NMS) and the sensitivity of each item of the Unified Multiple System Atrophy Rating Scale (UMSARS) to change remain unclear in Chinese patients with early-stage multiple system atrophy (MSA). We investigated the evolution of motor symptoms and NMS in early-stage MSA and the sensitivity of each item included in the UMSARS to change over a 2-year follow-up. METHODS: Motor symptoms and NMS were recorded at baseline and at 1- and 2-year follow-ups based on the UMSARS and the NMS scale. Generalized estimating equation models were used. The sensitivity of an item included in the UMSARS to change was assessed by calculating a standardized effect using the mean annual change divided by the standard deviation of the change. RESULTS: We enrolled 246 consecutive patients with MSA and 97 MSA completed the 2-year follow-up. The mean total UMSARS score increased by 11.90 and 22.54 points at the 1- and 2-year follow-ups, respectively. UMSARS-I items associated with motor functions were more sensitive to change and those associated with autonomic dysfunction showed less sensitivity to change. Items 4 (tremor at rest), 5 (action tremor), and 3 (ocular motor dysfunction) of the UMSARS-II were less sensitive to change. The prevalence and severity of NMS significantly increased over the 2-year follow-up. CONCLUSIONS: We observed significant progression in motor symptoms and NMS in patients with early-stage MSA. Our results provide useful information to support the revision of the UMSARS.

Mutation Screening of TFG in α-Synucleinopathy and Amyotrophic Lateral Sclerosis.

BACKGROUND: Recently, p.R383H in TFG was identified as the disease cause in a family with α-synucleinopathy and amyotrophic lateral sclerosis (ALS). However, no further replication has been conducted in larger cohorts. OBJECTIVE: The aim was to explore the genetic role of TFG in α-synucleinopathy and ALS. METHODS: We analyzed the rare protein-coding variants in patients with Parkinson's disease (PD), ALS, multiple system atrophy (MSA), spastic paraplegia (N = 2709), and 7536 controls with whole-exome sequencing. RESULTS: Nine rare variants were identified in PD and two in MSA. One PD patient carried the same variant p.R383H. Similarly, this patient developed early-onset PD with bradykinesia and rigidity on the left side as the initial symptoms. However, at the gene level, rare variants of TFG were not enriched in patients. CONCLUSIONS: Rare variants of TFG were not enriched in α-synucleinopathy and ALS. However, we could not deny the potential pathogenicity of specific variants such as p.R383H. Further exploration is still necessary. © 2022 International Parkinson and Movement Disorder Society.

Genetic Determinants of Survival in Parkinson's Disease in the Asian Population.

BACKGROUND: Patients with Parkinson's disease (PD) have reduced life expectancy compared to the general population. Genetic variation was shown to play a role in the heterogeneity of survival for patients with PD, although the underlying genetic background remains poorly studied. OBJECTIVE: The aim was to explore the genetic determinants influencing the survival of PD. METHODS: We performed a genome-wide association analysis using a Cox proportional hazards model in a longitudinal cohort of 1080 Chinese patients with PD. Furthermore, we built a clinical-genetic model to predict the survival of patients using clinical variables combined with polygenic risk score (PRS) of survival of PD. RESULTS: The cohort was followed up for an average of 7.13 years, with 85 incidents of death. One locus rs12628329 (RPL3) was significantly associated with reduced survival time by ~10.8 months (P = 2.72E-08, ß = 1.79, standard error = 0.32). Functional exploration suggested this variant could upregulate the expression of RPL3 and induce apoptosis and cell death. In addition, adding PRS of survival in the prediction model substantially improved survival predictability (concordance index [Cindex]: 0.936) compared with the clinical model (Cindex: 0.860). CONCLUSIONS: These findings improve the current understanding of the genetic cause of survival of PD and provide a novel target RPL3 for further research on PD pathogenesis and potential therapeutic options. Our results also demonstrate the potential utility of PRS of survival in identifying patients with shorter survival and providing personalized clinical monitoring and treatment. © 2022 International Parkinson and Movement Disorder Society.

Spatial-temporal pattern of propagation in amyotrophic lateral sclerosis and effect on survival: A cohort study.

BACKGROUND AND PURPOSE: Clarification of propagation patterns in amyotrophic lateral sclerosis (ALS) is challenging, but understanding these has implications for individual prognostication and clinical trial design. However, systematic knowledge in this area is lacking. The aim of this study was to characterize the spatial and temporal features of propagation patterns in ALS, and to evaluate the association between propagation patterns and survival. METHODS: A cohort of 833 patients with ALS, diagnosed between January 2018 and December 2019 and followed to August 2021, was analysed. Spatial and temporal features of propagation patterns were determined based on the involved functional regions (bulbar, cervical, thoracic/respiratory and lumbar) in time order. The final propagation pattern was identified in patients with at least three functional regions involved. Kaplan-Meier analysis and Cox regression analysis were performed. RESULTS: During a median follow-up of 21.2 months, 19 final propagation patterns were identified in 657 patients (78.9%). In survival analysis, we found that the earlier the respiratory functional region becomes involved, the higher the risk of death (time order: 1st: hazard ratio [HR], 3.35, 95% confidence interval [CI] 1.23-9.15; 2nd: HR 2.45, 95% CI 1.55-3.87; 3rd: HR 1.94, 95% CI 1.52-2.49), adjusting for age, sex, diagnostic delay, revised ALS Functional Rating Scale score, cognitive impairment and riluzole. Shorter interval time between involved regions was an independent adverse prognostic factor. CONCLUSIONS: The propagation patterns of ALS are varied. The order in which the respiratory region becomes involved and the interval time between involvement of functional regions are predictors for prognosis.

The mutation spectrum of Parkinson-disease-related genes in early-onset Parkinson's disease in ethnic Chinese.

BACKGROUND AND PURPOSE: Recent genetic progress has shown many causative/risk genes linked to Parkinson's disease (PD), mainly in patients of European ancestry. The study aimed to investigate the PD-related genes and determine the mutational spectrum of early-onset PD in ethnic Chinese. METHODS: In this study, whole-exome sequencing and/or gene dosage analysis were performed in 704 early-onset PD (EOPD) patients (onset age ≤45 years) and 1866 controls. Twenty-six PD-related genes and 20 other genes linked to neurodegenerative and lysosome diseases were analysed. RESULTS: Eighty-two (11.6%, 82/704) EOPD patients carrying rare pathogenic/likely pathogenic variants in PD-related genes were identified. The mutation frequency in autosomal recessive inheritance EOPD (42.9%, 27/63) was much higher than that in autosomal dominant inheritance EOPD (0.9%, 12/110) or sporadic EOPD (8.1%, 43/531). Bi-allelic mutations in PRKN were the most frequent, accounting for 5.1% of EOPD cases. Three common pathogenic variants, p.A53V in SNCA, p.G284R in PRKN and p.P53Afs*38 in CHCHD2, occur exclusively in Asians. The putative damaging variants from GBA, PRKN, DJ1, PLA2G6 and GCH1 contributed to the collective risk for EOPD. Notably, the protein-truncating variants in CHCHD2 were enriched in EOPD, especially for p.P53Afs*38, which was also found in three patients from an independent cohort of patients with late-onset PD (n = 1300). Functional experiments confirmed that truncated CHCHD2 variants cause loss of function and are linked to mitochondrial dysfunction. CONCLUSIONS: Our study reveals that the genetic spectrum of EOPD in Chinese, which may help develop genetic scanning strategies, provided more evidence supporting CHCHD2 in PD.

Genetic Modifiers of Age at Onset for Parkinson's Disease in Asians: A Genome-Wide Association Study.

BACKGROUND: Age at onset (AAO) is an essential feature of Parkinson's disease (PD) and can help predict disease progression and mortality. Identification of genetic variants influencing AAO of PD could lead to a better understanding of the disease's biological mechanism and provide clinical guidance. However, genetic determinants for AAO of PD remain mostly unknown, especially in the Asian population. OBJECTIVES: To identify genetic determinants for AAO of PD in the Asian population. METHODS: We performed a genome-wide association meta-analysis on AAO of PD in 5166 Chinese patients with PD (Ndiscovery  = 3628, Nreplication  = 1538). We then conducted a further cross-ethnic meta-analysis using our results and summary statistics for the AAO of PD from the European population. RESULTS: The total heritability of AAO of PD was around 0.10 ~ 0.14, similar to that (~0.11) estimated in populations of European ancestry. One novel significant intergenic locus rs9783733 (NDN; PWRN4) was identified (P = 3.14E-09, beta = 2.30, SE = 0.39). Remarkably, this variant could delay AAO of PD by ~2.43 years, with a more considerable effect on males (~3.18 years) than females (~1.45 years). The variant was suggestively significant in the cross-ethnic meta-analysis and suggested a positive selection in the East Asian population. Additionally, cross-ethnic meta-analysis identified a significant locus rs356203 in SNCA (P = 2.35E-11, beta = -0.71, SE = 0.01). CONCLUSIONS: These findings improve the current understanding of the genetic etiology of AAO of PD in different ethnic groups, and provide a new target for further research on PD pathogenesis and potential therapeutic options. © 2021 International Parkinson and Movement Disorder Society.

Abnormal eye movements in spinocerebellar ataxia type 3.

BACKGROUND: Abnormal eye movements are common in spinocerebellar ataxias Type 3 (SCA3). We conducted the research to explore the frequency of abnormal eye movements in Chinese patients with SCA3, to compare the demographic and clinical characteristics between SCA3 patients with and without each type of abnormal eye movement, and to explore the correlation between abnormal eye movements and the severity of ataxia. METHODS: Seventy-four patients with SCA3 were enrolled in this cross-sectional study. Six types of abnormal eye movements including impaired smooth pursuit, increased square-wave jerks (SWJ), gaze-evoked nystagmus (GEN), slowing of saccades, saccadic hypo/hypermetria and supranuclear gaze palsy were evaluated by experienced neurologists. The severity of ataxia was evaluated by Scale for the Assessment and Rating of Ataxia (SARA). RESULTS: The prevalence of impaired smooth pursuit, increased SWJ, GEN, slowing of saccades, saccadic hypo/hypermetria and supranuclear gaze palsy in Chinese SCA3 patients was 28.4, 13.5, 78.4, 41.9, 23.0, and 5.4%, respectively. SCA3 patients with GEN had higher scores of International Cooperative Ataxia Rating Scale (ICARS-IV) and total ICARS, and longer length of CAG repeat than patients without GEN. SCA3 patients with slowing of saccades had a longer disease duration, higher scores of ICARS-I, ICARS-II, total ICARS and SARA than patients without slowing of saccades. SCA3 patients with saccadic hypo/hypermetria had higher scores of ICARS-III, ICARS-IV, and SARA than patients without saccadic hypo/hypermetria. The demographic and clinical characteristics did not differ significantly between SCA3 patients with and without impaired smooth pursuit, increased SWJ, or supranuclear gaze palsy. Multivariate linear regression showed that the number of abnormal eye movements (0-6), disease duration, Hamilton Depression Rating Scale-24 (HDRS-24) score, and CAG repeat length were positively correlated with SARA score, whereas Montreal Cognitive Assessment (MoCA) score was negatively correlated with SARA score in SCA3. CONCLUSIONS: An increased number of abnormal eye movement types correlated with the severity of ataxia in SCA3.

Facial tremor in patients with Parkinson's disease: prevalence, determinants and impacts on disease progression.

BACKGROUND: Facial (lip and jaw) tremor (FT) is associated with Parkinson's disease (PD) but few studies have been conducted to explore its clinical profile. We performed this study to investigate the prevalence and clinical correlates of FT in PD, and further to evaluate its effect on disease progression. METHODS: A retrospective, cross-sectional (n = 2224) and longitudinal (n = 674) study was conducted. The presence of FT was based on a ≥ 1 score in the United PD Rating Scale (UPDRS) item 20A. Group comparisons were conducted, followed by a forward binary logistic regression analysis. Inverse probability of treatment weighting (IPTW) based on the propensity score and weighted or unweighted Cox regression models were used to explore the impact of FT on five clinical milestones including death, UPDRS III 11-point increase, Hoehn and Yahr (H&Y) stage reaching 3, dyskinesia development, and Montreal Cognitive Assessment 3-point decrease. RESULTS: FT was presented in 403 patients (18.1%), which showed increasing trends with disease duration and H&Y score. Age (P < 0.001), female (P < 0.001), disease duration (P = 0.001), speech (P = 0.011), rigidity (P = 0.026), rest tremor on limbs (P < 0.001), kinetic tremor on hands (P < 0.001), and axial symptoms (P = 0.013) were independent factors associated with FT. Both unweighted and weighted Cox regression models indicated that baseline FT and FT as the initial symptom were not associated with the five outcomes. CONCLUSIONS: Our study suggested that FT was not uncommon and provided a deeper insight into the characteristics of FT in PD. The predict value of FT on long-term progronis of PD may need future longer follwe-up study.

Mutation Analysis of DNAJC Family for Early-Onset Parkinson's Disease in a Chinese Cohort.

BACKGROUND: Recently, members of the DnaJ homolog C (DNAJC) family have been identified to be associated with Parkinson's disease (PD) and other neurodegenerative disorders. However, most studies are based on European-ancestry population and no comprehensive analysis is further conducted. OBJECTIVES: In this study, we aim to systematically explore the associations of DNAJCs by genetic analysis in a large Chinese early-onset PD (EOPD) cohort. METHODS: Rare variants were identified using whole exome sequencing in a cohort of 664 unrelated patients with EOPD. Allelic association analysis was performed with Fisher's exact test to clarify the associations at allele level. Gene-based burden analysis was conducted for both rare variants and damaging variants to illuminate the involvement of DNAJCs in EOPD at the gene level. RESULTS: In total, 61 rare variants were identified in the current study. At the allele level, 2 variants, p.T1109R and p.L174H, in DNAJC26 were significant after Bonferroni correction; 2 variants, p.V1271A and p.A476V, in DNAJC26; 2 variants, p.M477T and p.D1670G, in DNAJC13; 1 variant, p.L19I, in DNAJC10; and 1 variant, p.N526S, in DNAJC6 reached nominal significance. Moreover, a novel compound heterozygous mutation in DNAJC6 was identified. At the gene level, gene-based burden analysis showed a clear enrichment of rare variants in DNAJC26 in patients with EOPD, but not other DNAJCs. CONCLUSIONS: Our work identifies novel rare variants of DNAJC26 to be associated with EOPD and enhances our understanding of the role of DNAJC family members in EOPD. © 2020 International Parkinson and Movement Disorder Society.

Evaluating the Role of SNCA, LRRK2, and GBA in Chinese Patients With Early-Onset Parkinson's Disease.

BACKGROUND: Defects in the α-synuclein, leucine-rich repeat kinase 2, or glucocerebrosidase genes have been regarded as essential contributors to PD. However, genetic variability of these genes with respect to early-onset PD remains poorly defined for the Chinese demographic. OBJECTIVES: We aim to systematically characterize the clinical and genetic architecture of α-synuclein, leucine-rich repeat kinase 2, and glucocerebrosidase in Chinese early-onset PD patients. METHODS: Whole-exome sequencing and Sanger sequencing were used to identify variants of α-synuclein, leucine-rich repeat kinase 2, and glucocerebrosidase in 662 Chinese early-onset PD patients. Haplotype and burden analyses were conducted to investigate the role of rare variants of these three genes in early-onset PD. RESULTS: Sixty rare variants, including 23 novel variants, were identified in 73 patients (11.0%). Frequencies of patients with rare pathogenic/likely pathogenic variants of α-synuclein, leucine-rich repeat kinase 2, and glucocerebrosidase were 0.6%, 3.0%, and 5.4%, respectively. Evidences of two founder events exclusive to Asians were identified in 2 patients with leucine-rich repeat kinase 2 p.R1441C and 3 patients with α-synuclein p.A53V. Gene-based burden analysis supported glucocerebrosidase as a strong risk factor for early-onset PD, but argued against over-representation of rare variants in α-synuclein or leucine-rich repeat kinase 2 in early-onset PD. Clinically, no differences in motor or nonmotor symptoms were found between glucocerebrosidase variants carriers, and noncarriers or between leucine-rich repeat kinase 2 carriers and noncarriers. Patients with α-synuclein variants showed both rapid progression and worse cognitive impairment. CONCLUSION: Our study provides a better understanding of the clinical and genetic correlations of α-synuclein, leucine-rich repeat kinase 2, and glucocerebrosidase in early-onset PD, which may be beneficial for drafting genetic scanning strategies and evaluating disease progression. © 2020 International Parkinson and Movement Disorder Society.