Association of TRMT2B gene variants with juvenile amyotrophic lateral sclerosis.

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by progressive degeneration of motor neurons, and it demonstrates high clinical heterogeneity and complex genetic architecture. A variation within TRMT2B (c.1356G>T; p.K452N) was identified to be associated with ALS in a family comprising two patients with juvenile ALS (JALS). Two missense variations and one splicing variation were identified in 10 patients with ALS in a cohort with 910 patients with ALS, and three more variants were identified in a public ALS database including 3317 patients with ALS. A decreased number of mitochondria, swollen mitochondria, lower expression of ND1, decreased mitochondrial complex I activities, lower mitochondrial aerobic respiration, and a high level of ROS were observed functionally in patient-originated lymphoblastoid cell lines and TRMT2B interfering HEK293 cells. Further, TRMT2B variations overexpression cells also displayed decreased ND1. In conclusion, a novel JALS-associated gene called TRMT2B was identified, thus broadening the clinical and genetic spectrum of ALS.

Mutation and clinical analysis of the CLCC1 gene in amyotrophic lateral sclerosis patients from Central South China.

INTRODUCTION: Recently, chloride channel CLIC-like 1 (CLCC1) was reported to be a novel ALS-related gene. We aimed to screen CLCC1 variants in our ALS cohort and further explore the genotype-phenotype correlation of CLCC1-related ALS. METHODS: We screened rare damaging variants in CLCC1 from our cohorts of 1005 ALS patients and 1224 healthy controls with whole-exome sequencing in Central South China. Fisher's exact test was conducted for association analysis at the entire gene level and single variant level. RESULTS: In total, four heterozygous missense variants in CLCC1 were identified from four unrelated sporadic ALS patients and predicted to be putative pathogenic by in silico tools and protein model prediction, accounting for 0.40% of all patients (4/1005). The four variants were c.A275C (p.Q92P), c.G1139A (p.R380K), c.C1244T (p.T415M), and c.G1328A (p.R443Q), respectively, which had not been reported in ALS patients previously. Three of four variants were located in exon 10. Patients harboring CLCC1 variants seemed to share a group of similar clinical features, including earlier age at onset, rapid progression, spinal onset, and vulnerable cognitive status. Statistically, we did not find CLCC1 to be associated with the risk of ALS at the entire gene level or single variant level. CONCLUSION: Our findings further expanded the genetic and clinical spectrum of CLCC1-related ALS and provided more genetic evidence for anion channel involvement in the pathogenesis of ALS, but further investigations are needed to verify our findings.

ALS-plus related clinical and genetic study from China.

BACKGROUND: Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disorder. An increasing number of researchers have found extra motor features in ALS, which are also called ALS-plus syndromes. Besides, a great majority of ALS patients also have cognitive impairment. However, clinical surveys of the frequency and genetic background of ALS-plus syndromes are rare, especially in China. METHODS: We investigated a large cohort of 1015 patients with ALS, classifying them into six groups according to different extramotor symptoms and documenting their clinical manifestations. Meanwhile, based on their cognitive function, we divided these patients into two groups and compared demographic characteristics. Genetic screening for rare damage variants (RDVs) was also performed on 847 patients. RESULTS: As a result, 16.75% of patients were identified with ALS-plus syndrome, and 49.5% of patients suffered cognitive impairment. ALS-plus group had lower ALSFRS-R scores, longer diagnostic delay time, and longer survival times, compared to ALS pure group. RDVs occurred less frequently in ALS-plus patients than in ALS-pure patients (P = 0.042) but showed no difference between ALS-cognitive impairment patients and ALS-cognitive normal patients. Besides, ALS-cognitive impairment group tends to harbour more ALS-plus symptoms than ALS-cognitive normal group (P = 0.001). CONCLUSION: In summary, ALS-plus patients in China are not rare and show multiple differences from ALS-pure patients in clinical and genetic features. Besides, ALS-cognitive impairment group tends to harbour more ALS-plus syndrome than ALS-cognitive normal group. Our observations correspond with the theory that ALS involves several diseases with different mechanisms and provide clinical validation.

Brain metabolic signatures in patients with genetic and nongenetic amyotrophic lateral sclerosis.

AIMS: To study the brain metabolic signature in Chinese amyotrophic lateral sclerosis (ALS) patients and compare the difference in brain metabolic patterns between ALS with and without genetic variants. METHODS: We included 146 patients with ALS and 128 healthy controls (HCs). All patients with ALS underwent genetic testing to screen for ALS related genetic variants and were then divided into genetic (n = 22) and nongenetic ALS (n = 93) subgroups. All participants underwent brain 18 F-FDG-PET scans. Group comparisons were performed using the two-sample t-test model of SPM12. RESULTS: We identified a large of hypometabolic clusters in ALS patients as compared with HCs, especially in the bilateral basal ganglia, midbrain, and cerebellum. Moreover, hypometabolism in the bilateral temporal lobe, precentral gyrus and hypermetabolism in the left anterior cingulate, occipital lobe, and bilateral frontal lobe were also found in ALS patients as compared with HCs. Compared with nongenetic ALS patients, genetic ALS patients showed hypometabolism in the right postcentral gyrus, precuneus, and middle occipital gyrus. The incidence of sensory disturbance in patients with genetic ALS was higher than that in patients with nongenetic ALS (5 of 22 [22.72%] vs. 7 of 93 [7.52%], p = 0.036). CONCLUSIONS: Our investigation provided unprecedented evidence of relative hypometabolism in the midbrain and cerebellum in ALS patients. Genetic ALS patients showed a specific signature of brain metabolism and a higher incidence of sensory disturbance, indicating that genetic factors may be an underlying cause affecting the brain metabolism and increasing the risk of sensory disturbance in ALS.

Genetic and clinical analysis of TP73 gene in amyotrophic lateral sclerosis patients from Chinese mainland.

Introduction: TP73 was recently identified as a novel causative gene for amyotrophic lateral sclerosis (ALS). We aimed to determine the contribution of variations in TP73 in the Chinese ALS population and to further explore the genotype-phenotype correlations. Methods: We screened rare, putative pathogenic TP73 mutations in a large Chinese ALS cohort and performed association analysis of both rare and common TP73 variations between cases and controls. Results: Of the 985 ALS patients studied, six rare, heterozygous putative pathogenic variants in TP73 were identified among six unrelated sALS patients. Exon 14 of TP73 might be a mutant hotspot in our cohort. Patients with ALS with only rare, putative pathogenic TP73 mutations exhibited a characteristic clinical profile. Patients harboring multiple mutations in TP73 and other ALS-related genes displayed a significantly earlier onset of ALS. Association analysis revealed that rare TP73 variants in the untranslated regions (UTRs) were enriched among ALS patients; meanwhile, two common variants in the exon-intron boundary were discovered to be associated with ALS. Discussion: We demonstrate that TP73 variations also have contributed to ALS in the Asian population and broaden the genotypic and phenotypic spectrum of TP73 variants in the ALS-frontotemporal dementia (FTD) spectrum. Furthermore, our findings first suggest that TP73 is not only a causative gene, but also exerts a disease-modifying effect. These results may contribute to a better understanding of the molecular mechanism of ALS.

Association of variants in the KIF1A gene with amyotrophic lateral sclerosis.

BACKGROUND: Amyotrophic lateral sclerosis (ALS) is a devastating progressive neurodegenerative disease that affects neurons in the central nervous system and the spinal cord. As in many other neurodegenerative disorders, the genetic risk factors and pathogenesis of ALS involve dysregulation of cytoskeleton and neuronal transport. Notably, sensory and motor neuron diseases such as hereditary sensory and autonomic neuropathy type 2 (HSAN2) and spastic paraplegia 30 (SPG30) share several causative genes with ALS, as well as having common clinical phenotypes. KIF1A encodes a kinesin 3 motor that transports presynaptic vesicle precursors (SVPs) and dense core vesicles and has been reported as a causative gene for HSAN2 and SPG30. METHODS: Here, we analyzed whole-exome sequencing data from 941 patients with ALS to investigate the genetic association of KIF1A with ALS. RESULTS: We identified rare damage variants (RDVs) in the KIF1A gene associated with ALS and delineated the clinical characteristics of ALS patients with KIF1A RDVs. Clinically, these patients tended to exhibit sensory disturbance. Interestingly, the majority of these variants are located at the C-terminal cargo-binding region of the KIF1A protein. Functional examination revealed that the ALS-associated KIF1A variants located in the C-terminal region preferentially enhanced the binding of SVPs containing RAB3A, VAMP2, and synaptophysin. Expression of several disease-related KIF1A mutants in cultured mouse cortical neurons led to enhanced colocalization of RAB3A or VAMP2 with the KIF1A motor. CONCLUSIONS: Our study highlighted the importance of KIF1A motor-mediated transport in the pathogenesis of ALS, indicating KIF1A as an important player in the oligogenic scenario of ALS.

Detection of changes in synaptic density in amyotrophic lateral sclerosis patients using 18 F-SynVesT-1 positron emission tomography.

BACKGROUND AND PURPOSE: Synaptic loss is well established as the major correlate of characteristic and consistent pathology in amyotrophic lateral sclerosis (ALS). We aimed to assess the possible discriminant diagnostic value of 18 F-SynVesT-1 positron emission tomography (PET) as a marker of ALS pathology and investigate whether specific synaptic density signatures are present in ALS with different subtypes. METHODS: Twenty-one patients with ALS and 25 healthy controls (HCs) were recruited. All participants underwent 18 F-SynVesT-1-PET. Synaptic density between ALS and HCs and between different ALS subgroups were compared. Correlation between synaptic density and clinical features in ALS was also analyzed. RESULTS: Low uptake distribution was found in the group comprising 21 ALS patients as compared with HCs in the right temporal lobe and the bilateral inferior frontal gyrus, anterior cingulate, and hippocampus-insula region. We also found low uptake in the bilateral superior temporal gyrus, hippocampus-insula, anterior cingulate, and left inferior frontal gyrus in ALS patients with cognitive impairment compared to HCs. Furthermore, compared to spinal onset ALS, bulbar onset ALS showed low uptake in the bilateral cingulate gyrus and high uptake in the bilateral superior temporal gyrus and left occipital lobe. No significant result was found in correlation analysis. CONCLUSIONS: This approach may provide a direct measure of synaptic density, and it therefore might represent a potentially useful biomarker for ALS diagnosis, as well as for estimating the cognitive decline and site of onset in ALS. 18 F-SynVesT-1-PET is presently not justified as a routine investigation to detect evidence of brain dysfunction leading to progression in ALS.

Profiling the Genome-Wide Landscape of Short Tandem Repeats by Long-Read Sequencing.

Background: Short tandem repeats (STRs) are highly variable elements that play a pivotal role in multiple genetic diseases and the regulation of gene expression. Long-read sequencing (LRS) offers a potential solution to genome-wide STR analysis. However, characterizing STRs in human genomes using LRS on a large population scale has not been reported. Methods: We conducted the large LRS-based STR analysis in 193 unrelated samples of the Chinese population and performed genome-wide profiling of STR variation in the human genome. The repeat dynamic index (RDI) was introduced to evaluate the variability of STR. We sourced the expression data from the Genotype-Tissue Expression to explore the tissue specificity of highly variable STRs related genes across tissues. Enrichment analyses were also conducted to identify potential functional roles of the high variable STRs. Results: This study reports the large-scale analysis of human STR variation by LRS and offers a reference STR database based on the LRS dataset. We found that the disease-associated STRs (dSTRs) and STRs associated with the expression of nearby genes (eSTRs) were highly variable in the general population. Moreover, tissue-specific expression analysis showed that those highly variable STRs related genes presented the highest expression level in brain tissues, and enrichment pathways analysis found those STRs are involved in synaptic function-related pathways. Conclusion: Our study profiled the genome-wide landscape of STR using LRS and highlighted the highly variable STRs in the human genome, which provide a valuable resource for studying the role of STRs in human disease and complex traits.

The Clinical and Polynucleotide Repeat Expansion Analysis of ATXN2, NOP56, AR and C9orf72 in Patients With ALS From Mainland China.

Background: Repeat expansions, including those in C9orf72 and ATXN2, have been implicated in amyotrophic lateral sclerosis (ALS). However, there have been few studies on the association of AR and NOP56 repeat expansion with ALS, especially in China. Accordingly, we aimed to evaluate the frequency of C9orf72 and ATXN2 repeat mutations and investigate whether NOP56 and AR repeat expansion are risk factors for ALS. Methods: In this study, 736 ALS patients and several hundred healthy controls were recruited. Polymerase chain reaction (PCR) and repeat-primed PCR (RP-PCR) were performed to determine the repeat lengths in C9orf72, ATXN2, AR, and NOP56. Results: GGGGCC repeats in C9orf72 were observed in six ALS patients (0.8%, 6/736) but not in any of the controls (0/365). The patients with pathogenic GGGGCC repeats showed shorter median survival times than those with a normal genotype (p = 0.006). Regarding ATXN2 CAG repeats, we identified that intermediate repeat lengths (29-34 copies) were associated with ALS (p = 0.033), and there was no difference in clinical characteristics between the groups with and without intermediate repeats (p > 0.05). Meanwhile, we observed that there was no association between the repeat size in AR and NOP56 and ALS (p > 0.05). Conclusions: Our results demonstrated that pathogenetic repeats in C9orf72 are rare in China, while intermediate CAG repeats in ATXN2 are more frequent but have no effect on disease phenotypes; the repeat size in AR and NOP56 may not be a risk factor for ALS.

Mitochondrial genome variations are associated with amyotrophic lateral sclerosis in patients from mainland China.

BACKGROUND: Amyotrophic lateral sclerosis (ALS) is a late-onset neurodegenerative disorder. Mitochondrial dysfunction is involved in the complex pathophysiology of ALS; however, the role of mitochondrial DNA (mtDNA) variants in ALS is poorly understood. We aimed to elucidate the role of mtDNA variants in the pathogenesis of ALS. METHODS: The mitochondrial haplogroups of 585 ALS patients and 371 healthy controls were determined; 38 ALS patients and 42 controls underwent long-range polymerase chain reaction combined with next-generation sequencing technology to analyze whole mitochondrial genome variants. RESULTS: A higher percentage of variants accumulated in ALS patients than in controls. Analysis of coding region variations that were further stratified by mtDNA genes revealed that nonsynonymous variants were more vulnerable in ALS patients than in controls, particularly in the ND4L, ND5, and ATP8 genes. Moreover, pathogenic nonsynonymous variants tended to over-represent in ALS patients. Unsurprisingly, nonsynonymous variants were not related to the phenotype. Haplogroup analysis did not found evidence of association between haplogroups with the risk of ALS, however, patients belonging to haplogroup Y and M7c were prone to develop later onset of ALS. CONCLUSIONS: This is the first study to profile mtDNA variants in ALS patients from mainland China. Our results suggest that an increase in the number of nonsynonymous variants is linked to the pathogenesis of ALS. Moreover, haplogroup Y and M7c may modulate the clinical expression of ALS. Our findings provide independent, albeit limited, evidence for the role of mtDNA in the pathogenesis of ALS.

Mutation spectrum of amyotrophic lateral sclerosis in Central South China.

To analyze the mutational spectrum of known ALS causative genes in China ALS patients. We comprehensively analyzed 51 ALS causative genes by combining different sequencing technologies in 753 unrelated ALS patients from Central South China. The mean age at onset (AAO) was 53.7±11.4 years. The AAO was earlier in the autosomal dominant (AD) ALS patients than in the sporadic ALS (sALS) patients. Bulbar onset was more frequent in females than in males. SOD1 was the most frequently mutated gene in the AD-ALS and the sALS patients, followed by the ATXN2 and FUS genes in the AD-ALS patients and the NEK1 and CACNA1H genes in the sALS patients. Patients with RDVs in the SOD1 or FUS genes had an earlier AAO than the mean AAO of all the patients, while the patients with RDVs in the NEK1 gene showed later onset. SOD1 gene was the most commonly mutated gene in ALS patients in China, followed by ATXN2 and NEK1. The phenotype might be determined synergistically by sex and genetic variants.

Evaluation of Peripheral Immune Activation in Amyotrophic Lateral Sclerosis.

Accumulating evidence has revealed that immunity plays an important role in amyotrophic lateral sclerosis (ALS) progression. However, the results regarding the serum levels of immunoglobulin and complement are inconsistent in patients with ALS. Although immune dysfunctions have also been reported in patients with other neurodegenerative diseases, few studies have explored whether immune dysfunction in ALS is similar to that in other neurodegenerative diseases. Therefore, we performed this study to address these gaps. In the present study, serum levels of immunoglobulin and complement were measured in 245 patients with ALS, 65 patients with multiple system atrophy (MSA), 60 patients with Parkinson's disease (PD), and 82 healthy controls (HCs). Multiple comparisons revealed that no significant differences existed between patients with ALS and other neurodegenerative diseases in immunoglobulin and complement levels. Meta-analysis based on data from our cohort and eight published articles was performed to evaluate the serum immunoglobulin and complement between patients with ALS and HCs. The pooled results showed that patients with ALS had higher C4 levels than HCs. In addition, we found that the IgG levels were lower in early-onset ALS patients than in late-onset ALS patients and HCs, and the correlations between age at onset of ALS and IgG or IgA levels were significant positive. In conclusion, our data supplement existing literature on understanding the role of peripheral immunity in ALS.

Rare, pathogenic variants in LRP10 are associated with amyotrophic lateral sclerosis in patients from mainland China.

Low-density lipoprotein receptor-related protein 10 (LRP10) is associated with a series of neurodegenerative diseases, such as Alzheimer's disease and Parkinson's disease which share genetic risk factors and pathophysiological processes with amyotrophic lateral sclerosis (ALS). To investigate whether LRP10 variants could cause a predisposition to ALS, we screened rare, pathogenic LRP10 variants among a cohort of 584 patients with ALS from mainland China and performed burden analysis using data from a large external database. A total of 7 rare, pathogenic variants in LRP10, of which one (c.1182A>T, p.R394S) was novel, were identified in 11 unrelated patients. Burden analysis revealed significant associations between ALS and LRP10 at both the gene and single-variant levels (c.1721G>A, p.R574Q; c.1182A>T, p.R394S; and c.1681C>T, p.R561C). Interestingly, patients with sporadic ALS carrying variant c.1721G>A tended to have a bulbar onset, increased phenotype severity, and a worse prognosis. Our findings first provide independent evidence that rare, pathogenic LRP10 variants may be risk factors for ALS and delineate a special phenotype in patients with sporadic ALS carrying variant c.1721G>A.

Mutation analysis of MFSD8 in an amyotrophic lateral sclerosis cohort from mainland China.

Recent studies have suggested that rare variants in MFSD8 contribute to risk for frontotemporal dementia (FTD). Considering the common underlying pathogenesis and the shared genetic risk between amyotrophic lateral sclerosis (ALS) and FTD, we screened the coding region of MFSD8 in 551 unrelated patients with ALS (510 unrelated sporadic ALS and 41 familial ALS probands) from mainland China by whole-exome sequencing to assess its mutation frequency in patients with ALS and evaluate its association. Two rare deleterious variants, c.343G>A (p. V115M) and c.695T>C (p.L232P), were identified in this study. The variant c.695T>C (p.L232P) has not been previously reported and the carrier of this variant exhibits a relatively younger age of disease onset. Our studies provide some independent evidence showing that the rare variant p.L232P in MFSD8 might be a candidate risk factor for ALS. However, the relatively small sample size and the lack of patient-derived cells limit the power of the genetic exploration of this study, further robust multicenter studies with larger sizes and biological experiments with patient-derived cells are needed to elucidate the pathogenesis of the rare variant in MFSD8 in ALS.

A Novel Potentially Pathogenic Rare Variant in the DNAJC7 Gene Identified in Amyotrophic Lateral Sclerosis Patients From Mainland China.

Variants in the DNAJC7 gene have been shown to be novel causes of amyotrophic lateral sclerosis (ALS). However, the contributions of DNAJC7 mutations in Asian ALS patients remain unclear. In this study, we screened rare pathogenic variants in the DNAJC7 gene in a cohort of 578 ALS patients from Mainland China. A novel, rare, putative pathogenic variant c.712A>G (p.R238G) was identified in one sporadic ALS patient. The carrier with this variant exhibited symptom onset at a relatively younger age and experienced rapid disease progression. Our results expand the pathogenic variant spectrum of DNAJC7 and indicate that variants in the DNAJC7 gene may also contribute to ALS in the Chinese population.

Identification of GGC repeat expansion in the NOTCH2NLC gene in amyotrophic lateral sclerosis.

OBJECTIVE: To determine whether the GGC repeats in the NOTCH2NLC gene contribute to amyotrophic lateral sclerosis (ALS). METHODS: In this study, 545 patients with ALS and 1,305 healthy controls from mainland China were recruited. Several pathogenic mutations in known ALS-causative genes (including C9ORF72 and ATXN2) and polynucleotide repeat expansions in NOP56 and AR genes were excluded. Repeat-primed PCR and GC-rich PCR were performed to determine the GGC repeat size in NOTCH2NLC. Systematic and targeted clinical evaluations and investigations, including skin biopsy and dynamic electrophysiologic studies, were conducted in the genetically affected patients. RESULTS: GGC repeat expansion was observed in 4 patients (numbers of repeats 44, 54, 96, and 143), accounting for ≈0.73% (4 of 545) of all patients with ALS. A comparison with 1,305 healthy controls revealed that GGC repeat expansion in NOTCH2NLC was associated with ALS (Fisher exact test, 4 of 545 vs 0 of 1,305, p = 0.007). Compared to patients with the neuronal intranuclear inclusion disease (NIID) muscle weakness-dominant subtype, patients with ALS phenotype carrying the abnormal repeat expansion tended to have a severe phenotype and rapid deterioration. CONCLUSION: Our results suggest that ALS is a specific phenotype of NIID or that GGC expansion in NOTCH2NLC is a factor that modifies ALS. These findings may help clarify the pathogenic mechanism of ALS and may expand the known clinical spectrum of NIID.

Association Between Vitamins and Amyotrophic Lateral Sclerosis: A Center-Based Survey in Mainland China.

To date, conflicting results about the role of vitamins in amyotrophic lateral sclerosis (ALS) have been reported along with a lack of systematic studies on all types of serum vitamins in patients with ALS. Moreover, extensive studies have been conducted on vitamins in other neurodegenerative diseases; however, whether serum vitamin alterations in ALS are similar to those in other neurodegenerative diseases remains unclear. Therefore, we performed a study involving a large Chinese cohort of patients with ALS to address this gap. In this study, 202 patients with ALS, 214 with a neurodegenerative disease that mimicked ALS (mimics), and 208 healthy controls were enrolled. Serum vitamins of all subjects were examined under fasting state in Clinical Laboratory. As a result, we found that higher vitamin A and E levels and lower vitamin B2, B9, and C levels were in patients with ALS compared to healthy controls, and that high vitamin A and E levels, and low vitamin B2, B9, and C levels were associated with an increased risk for ALS. In addition, serum vitamin C was lower in early-onset ALS patients compared to those in late-onset ALS patients; however, there was no significant correlation between serum vitamins and age at onset, sites at onset, disease duration, or disease severity of ALS. We also found that patients with ALS showed similar vitamin alterations to mimics, with the exception of vitamin E. In summary, our study adds information to the literature on the role of vitamins in ALS and provides support for clinical guidance regarding dietary changes and vitamin supplements in patients with ALS.

Mutation analysis of GLT8D1 and ARPP21 genes in amyotrophic lateral sclerosis patients from mainland China.

Variants in exon 4 of gene encoding GLT8D1 (glycosyltransferase 8 domain containing 1) gene have recently been suggested as a novel cause of amyotrophic lateral sclerosis (ALS). In addition, there is a synergism between GLT8D1 and ARPP21 (cAMP Regulated Phosphoprotein 21) variants for ALS. However, this observation has not been validated in other ALS cohorts. In this study, we analyzed the rare pathogenic variants in GLT8D1 and ARPP21 genes in a cohort of 512 ALS patients and 3210 healthy controls from mainland China. A total of 25 rare variants in ARPP21 were identified in the patients and controls, but we did not find rare variants in exon 4 of GLT8D1 in the patients. By using Fisher's exact test, we did not find significant association between ALS and GLT8D1 or ARPP21. Therefore, GLT8D1 and ARPP21 are not likely the causative genes for ALS in mainland China.

Clinical findings of autosomal-dominant striatal degeneration and PDE8B mutation screening in parkinsonism and related disorders.

BACKGROUND: Autosomal-dominant striatal degeneration (ADSD) is a rare neurodegenerative movement disorder caused by mutations in the Phosphodiesterase 8B (PDE8B) gene. OBJECTIVE: To summarize the clinical and imaging features of a Chinese ADSD family and determine whether mutations in PDE8B are associated with Parkinson's disease (PD) or Parkinsonism. METHODS: Clinical, imaging and genetic findings in a Chinese ADSD family are reported. Rare, potentially pathogenic variants in PDE8B were searched in whole-exome sequencing datasets from 1714 PD or parkinsonism patients and 1039 controls. RESULTS: An ADSD diagnosis was confirmed by a nonsense mutation in PDE8B (p.E102X) in a patient and a presymptomatic carrier. Clinically, the patient exhibited progressive parkinsonism without tremor and ataxia phenotype. Neuroimaging showed an inhomogeneous increased signal in the patient's striatum on T1-weighted images but a decreased signal in the presymptomatic carrier. Diffusion tensor imaging (DTI) showed a disturbance in the white matter fiber distribution, especially between the lentiform nucleus and caudate nucleus, which was more prominent in the patient than in the presymptomatic carrier. Within the 1714 patients, three PDE8B missense variants were identified that were unlikely to be the cause of the parkinsonism phenotype according to the functional prediction and mutation types reported in ADSD. CONCLUSIONS: For the first time, we described the typical ataxia phenotype in ADSD. A loss of white matter fiber integrity was shown on DTI scanning. No causative PDE8B mutation was discovered in our cohort of PD or Parkinsonism patients.