Early autoimmunity and outcome in virus encephalitis: a retrospective study based on tissue-based assay.

To explore the autoimmune response and outcome in the central nervous system (CNS) at the onset of viral infection and correlation between autoantibodies and viruses. METHODS: A retrospective observational study was conducted in 121 patients (2016-2021) with a CNS viral infection confirmed via cerebrospinal fluid (CSF) next-generation sequencing (cohort A). Their clinical information was analysed and CSF samples were screened for autoantibodies against monkey cerebellum by tissue-based assay. In situ hybridisation was used to detect Epstein-Barr virus (EBV) in brain tissue of 8 patients with glial fibrillar acidic protein (GFAP)-IgG and nasopharyngeal carcinoma tissue of 2 patients with GFAP-IgG as control (cohort B). RESULTS: Among cohort A (male:female=79:42; median age: 42 (14-78) years old), 61 (50.4%) participants had detectable autoantibodies in CSF. Compared with other viruses, EBV increased the odds of having GFAP-IgG (OR 18.22, 95% CI 6.54 to 50.77, p<0.001). In cohort B, EBV was found in the brain tissue from two of eight (25.0%) patients with GFAP-IgG. Autoantibody-positive patients had a higher CSF protein level (median: 1126.00 (281.00-5352.00) vs 700.00 (76.70-2899.00), p<0.001), lower CSF chloride level (mean: 119.80±6.24 vs 122.84±5.26, p=0.005), lower ratios of CSF-glucose/serum-glucose (median: 0.50[0.13-0.94] vs 0.60[0.26-1.23], p=0.003), more meningitis (26/61 (42.6%) vs 12/60 (20.0%), p=0.007) and higher follow-up modified Rankin Scale scores (1 (0-6) vs 0 (0-3), p=0.037) compared with antibody-negative patients. A Kaplan-Meier analysis revealed that autoantibody-positive patients experienced significantly worse outcomes (p=0.031). CONCLUSIONS: Autoimmune responses are found at the onset of viral encephalitis. EBV in the CNS increases the risk for autoimmunity to GFAP.

Whole-Exome Sequencing Identified a Novel Mutation in RNF216 in a Family with Gordon Holmes Syndrome.

Gordon Holmes syndrome (GHS) is a rare disease characterized by hypogonadotropic hypogonadism (HH), progressive cognitive decline and variable movement disorders. Mutations in RNF216 have been found to be associated with GHS. Here, we identify a novel homozygous RNF216 p.E650X mutation causing GHS. The proband presented with onset dysarthria and developed cerebellar ataxia and cognitive impairment, with a history of azoospermia at the age of 28 years. Cerebellar atrophy and white matter lesions were found in the cerebral hemispheres and brainstem. Low gonadotropin serum levels were also observed. Whole-exome sequencing (WES) revealed a novel homozygous nonsense variant in RNF216, c.1948G>T; p.E650X. Our finding furthers the genetic knowledge of GHS and extends the ethnic distribution of RNF216 mutations.

Common genetic variants in PRRC2A are associated with both neuromyelitis optica spectrum disorder and multiple sclerosis in Han Chinese population.

BACKGROUND: The proline-rich coiled-coil 2A (PRRC2A) gene has been reported to underlie risk of various autoimmune diseases. However, no data reveal the risk susceptibility of PRRC2A to neuromyelitis optica spectrum disorder (NMOSD) and multiple sclerosis (MS) so far. OBJECTIVES: To explore the association between PRRC2A variants and NMOSD and MS susceptibility in Han Chinese population. METHODS: Totally, 207 NMOSD (98 AQP4+ and 109 AQP4-) patients, 141 MS and 196 healthy controls (HC) were enrolled. Candidate tagging single nucleotide polymorphisms (tag-SNPs) were selected from the 1000G database based on the Chinese data. SNP genotyping was performed using MassArray and Sanger sequencing. RESULTS: PRRC2A variants rs2736171, rs2736157, rs2844470 alter susceptibility to AQP4+ NMOSD, while rs2242659 to MS. Genotype AT of rs2844470 and AG of rs2242659 increased risk susceptibility for AQP4+ NMOSD and MS, respectively. AQP4+ NMOSD exhibited a higher frequency of genotype AG of rs2736157 compared with AQP4- NMOSD. Haplotype TCAAGGTAG was conferred risk susceptibility to AQP4+ NMOSD and haplotype TTAGAGTAG had a protective effect on both AQP4+ and AQP4- NMOSD. Further, we identified various gene expression levels in disease-related regions that are significantly modulated by three cis-eQTL SNPs rs2736157, rs2736171 and rs2242659 (p < 1.05 × 10-4). CONCLUSIONS: PRRC2A variants are first reported to be associated with NMOSD and MS. The identified PRRC2A variants may shed light on the pathogenesis of NMOSD and MS and potentially lead to an individualized therapeutic approach for both distinct disease entities.

A novel de novo RNF216 mutation associated with autosomal recessive Huntington-like disorder.

Mutations in RNF216 have been found to be associated with autosomal recessive Huntington-like disorder. Here, we describe a patient with Huntington-like disorder caused by a novel de novo RNF216 mutation. The patient started to have choreatic movements of both hands, slowly progressing to head, face, and four extremities, with prominent cognitive deterioration. White matter lesions in cerebral hemispheres and brainstem, cerebellar atrophy, and low gonadotropin serum levels have been demonstrated. We have identified a homozygous deletion of exon 2 in the RNF216 gene by whole-exome sequencing. Our findings increased genetic knowledge of autosomal recessive Huntington-like disorder and extended the ethnic distribution of RNF216 mutations.

Tuberous Sclerosis Complex in Chinese patients: Phenotypic analysis and mutational screening of TSC1/TSC2 genes.

PURPOSE: Tuberous sclerosis complex (TSC) is characterized by the development of hamartomas in multiple organ systems. This study attempted to screen mutations and to investigate the mutation distribution and related phenotypes including epilepsy of Chinese TSC patients. METHODS: We performed the genotypic analysis of TSC1 and TSC2 genes in 77 unrelated Chinese TSC patients using direct Sanger sequencing and Multiplex ligation-dependent probe amplification (MLPA). RESULTS: Mutations were identified in a total of 63 (81.8%) cases, including 18 TSC1 mutations (8 nonsense mutations, 6 frameshift, 1 in-frame shift, 1 missense and 2 splice-site) and 45 TSC2 mutations (13 missense, 3 nonsense, 6 splicing, 6 in-frame shift,12 frameshift mutations and 5 large deletions). Large deletions were presented exclusively in TSC2 gene, accounting for 7.9% of all mutations in this study. Fourteen novel mutations were identified in this study. CONCLUSIONS: Epilepsy occurs in approximately 75.3% (58/77) of patients. Hypomelanotic macules occurred significantly more often in patients with TSC2 mutations and cases with TSC1/TSC2 mutations had a significantly higher frequency of cortical nodule than patients with no mutations identified. Overall, our data expands the spectrum of mutations associated with the TSC loci and will be of value to the genetic counseling in patients with the disease.

Clinical features and mutation spectrum in Chinese patients with CADASIL: A multicenter retrospective study.

AIM: To characterize clinical features and mutation spectrum in Chinese patients with CADASIL. METHODS: We collected 261 clinically suspected Chinese CADASIL patients from three hospitals located in different regions of China. Sanger sequencing is performed to screen the exons 2 to 24 of NOTCH3 gene. Clinical and genetic data were retrospectively studied. Haplotype analyses were performed in patients carrying p.Arg544Cys and p.Arg607Cys, respectively. RESULTS: A total of 214 patients were finally genetically diagnosed as CADASIL, with 45 known NOTCH3 mutations and a novel c.1817G>T mutation. We found that patients carrying p.Arg607Cys or p.Arg544Cys mutation located in exon 11 occupied nearly 35% in our mutation spectrum. In retrospectively study of clinical data, we found a higher number of patients having cognitive impairment and a lower number of patients having migraine with aura. Furthermore, we identified that patients carrying mutations in exon 11 seemed to experience a later disease onset (p=6.8×10-5 ). Additionally, a common haplotype was found in patients from eastern China carrying p.Arg607Cys, and the patients from Fujian carrying p.Arg544Cys shared the same haplotype with patients from Taiwan carrying p.Arg544Cys. CONCLUSIONS: These findings broaden the mutational and clinical spectrum of CADASIL and provide additional evidences for the existence of founder effect in CADASIL patients.

Spectrum and Classification of ATP7B Variants in a Large Cohort of Chinese Patients with Wilson's Disease Guides Genetic Diagnosis.

BACKGROUND: Wilson's disease (WD) is an autosomal recessive disorder of copper metabolism caused by ATP7B pathogenic mutations. The symptoms of WD can be effectively prevented if the affected individuals are identified and intervened early. However, clinical utility of this molecular analysis is challenging due to hundreds of variants with various clinical effects in the gene. Here, we aim to describe the spectrum of ATP7B variants and assess their clinical effects in the Han Chinese population. METHODS: The ATP7B gene was directly sequenced in 632 unrelated WD patients and 503 unrelated healthy individuals. The effects of identified variants were classified according to the American College of Medical Genetics and Genomics (ACMG) standards and guidelines. Different frequency of variants observed in both cases and controls were tested using Chi-square or Fisher's exact tests. RESULTS: We detected 161 non-synonymous variants in these 632 WD patients, 58 of which were novel. Among these variants, 78, 64, 8, 4, and 7 were classified as 'pathogenic variants', 'likely pathogenic variants', 'variants with uncertain significance', 'likely benign variants', and 'benign variants', respectively. Ninety percent (569/632) of these WD patients can be genetically diagnosed with two or more 'pathogenic' or 'likely pathogenic' variants. The 14 most common disease-causing variants were found at least once in 94% (537/569) of genetically diagnosed patients. CONCLUSIONS: These data expand the spectrum of ATP7B variants and facilitate effective screening for ATP7B variants for early diagnosis of WD and development of individualized treatment regimens.

Variants of Interleukin-7/Interleukin-7 Receptor Alpha are Associated with Both Neuromyelitis Optica and Multiple Sclerosis Among Chinese Han Population in Southeastern China.

BACKGROUND: Neuromyelitis optica (NMO) and multiple sclerosis (MS) are autoimmune demyelinating diseases of the central nerve system. Interleukin-7 (IL-7) and interleukin-7 receptor alpha (IL-7Rα) were proved to be important in the pathogenesis of both diseases because of the roles they played in the differentiations of autoimmune lymphocytes. The variants of both genes had been identified to be associated with MS susceptibility in Caucasian, Japanese and Korean populations. However, the association of these variants with NMO and MS has not been well studied in Chinese Southeastern Han population. Here, we aimed to evaluate the association of six IL-7 variants (rs1520333, rs1545298, rs4739140, rs6993386, rs7816065, and rs2887502) and one variant of IL-7RA (rs6897932) with NMO and MS among Chinese Han population in southeastern China. METHODS: Matrix-assisted laser desorption/ionization time of flight mass spectrometry (MassARRAY system) and Sanger sequencing were used to determine the variants of IL-7 and IL-7RA in 167 NMO patients, 159 MS patients and 479 healthy controls among Chinese Han population in southeastern China. Samples were excluded if the genotyping success rate <90%. RESULTS: Statistical differences were observed in the genotypes of IL-7 rs1520333 in MS patients and IL-7RA rs6897932 in NMO patients, compared with healthy controls (P = 0.035 and 0.034, respectively). There was a statistically significant difference in the genotypes of IL-7 rs2887502 between MS and NMO patients (P = 0.014). And there were statistically significant differences in the rs6897932 genotypes (P = 0.004) and alleles (P = 0.042) between NMO-IgG positive patients and healthy controls. CONCLUSIONS: The study suggested that among Chinese Han population in southeastern China, the variant of IL-7RA (rs6897932) was associated with NMO especially NMO-IgG positive patients while the variant of IL-7 (rs1520333) with MS patients. And the genotypic differences of IL-7 rs2887502 between MS and NMO indicated the different genetic backgrounds of these two diseases.

Variants of Interferon Regulatory Factor 5 are Associated with Neither Neuromyelitis Optica Nor Multiple Sclerosis in the Southeastern Han Chinese Population.

BACKGROUND: Neuromyelitis optica (NMO) and multiple sclerosis (MS) are demyelinating disorders of the central nervous system. Interferon regulatory factor 5 (IRF5) is a common susceptibility gene to different autoimmune disorders. However, the association of IRF5 variants with NMO and MS patients has not been well studied. Therefore, we aimed to evaluate whether IRF5 variants were associated with NMO and MS in the Southeastern Han Chinese population. METHODS: Four single nucleotide polymorphisms (SNPs) were selected and genotyped by matrix-assisted laser desorption/ionization time of flight mass spectrometry in 111 NMO patients, 145 MS patients and 300 controls from Southeastern China. RESULTS: None of these 4 SNPs was associated with NMO or MS patients. CONCLUSIONS: Our preliminary study indicates that genetic variants in IRF5 may affect neither NMO nor MS in the Southeastern Han Chinese population. Further studies with a large sample size and diverse ancestry populations are needed to clarify this issue.

Variants of CYP27B1 are associated with both multiple sclerosis and neuromyelitis optica patients in Han Chinese population.

Multiple sclerosis (MS) and neuromyelitis optica (NMO) are chronic demyelinating diseases of the central nervous system (CNS). Recently, variants of vitamin D metabolizing genes, including rs12368653, rs10876994, rs118204009 and rs703842 in CYP27B1, and rs2248359 in CYP24A1 have been identified to be associated with the pathogenicity of MS in Caucasian populations. However, these results have not been replicated in Han Chinese population. Here we investigated the association of these variants with MS and NMO susceptibility in 149 MS patients, 110 NMO patients and 294 healthy controls using MassARRAY system and Sanger sequencing. We found that the frequencies of the A allele of rs703842 were higher in MS patients than controls (p=0.032), and statistical differences were observed in the genotypes of both rs703842 (p=0.013) and rs10876994 (p=0.001) between NMO patients and controls. In addition, we found difference in the genotype of rs12368653 between MS patients and controls (p=0.008). However, no difference was found in rs2248359 among these three groups. The reported rare mutation p.R389H (rs118204009) was not found in our study. In conclusion, our study suggested that variants of CYP27B1 were associated with both MS and NMO patients in Han Chinese population.

Variants of autophagy-related gene 5 are associated with neuromyelitis optica in the Southern Han Chinese population.

Neuromyelitis optica (NMO) and multiple sclerosis (MS) are autoimmune demyelinating diseases of the central nervous system. The discovery of NMO immunoglobulin G (NMO-IgG) antibody has improved the clinical definition of NMO. Recently, the autophagy-related genes (ATGs) have been proved to be associated with several autoimmune and inflammation diseases. Increased T cell expression of ATG5 may be correlated with the pathogenesis of inflammatory demyelination in MS. However, the association of ATG5 variants with MS and NMO patients has not been well studied. In this study, five ATG5 variants were genotyped in 144 MS patients, 109 NMO patients and 288 controls in the Han Chinese population. In the cohort of NMO patients, we observed that the CC genotype of rs548234 increased susceptibility to NMO (p = 0.016), while the allele T of rs548234 (p = 0.003) and the allele A of rs6937876 (p = 0.009) acted as protective factors for NMO-IgG positive NMO patients. However, no association was found between ATG5 variants and MS patients. These results indicated that ATG5 variants are associated with NMO but not MS patients, which may provide a clue for further clarifying the autoimmune mechanisms of autophagy-related pathogenesis in NMO.

No association between identified multiple sclerosis non-MHC risk loci and neuromyelitis optica.

Neuromyelitis optica (NMO) and multiple sclerosis (MS) are both autoimmune inflammatory and demyelinating disorders of the central nervous system. Recently, more than 50 MS-susceptibility single-nucleotide polymorphisms (SNPs) have been detected outside the major histocompatibility complex (MHC) region. In this study, we aimed to evaluate the association of these identified non-MHC MS risk loci with Chinese patients with NMO. Thirty-five non-MHC SNPs were selected and genotyped by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) in 110 NMO patients and 332 controls from southeastern China. Among the 35 SNPs, only one, rs1800693 in the TNFRSF1A locus, was nominally associated with NMO (P = 0.045, OR = 1.550, 95% CI = 1.007-2.384). However, none of the 35 SNPs was associated with NMO after Bonferroni correction. Our results showed no association between these identified non-MHC MS risk loci and NMO, suggesting there are genetic differences in the etiology of NMO and MS.

Novel SLC20A2 mutations identified in southern Chinese patients with idiopathic basal ganglia calcification.

Idiopathic basal ganglia calcification (IBGC) is a rare neuropsychiatric disorder characterized by bilateral and symmetric cerebral calcifications. Recently, SLC20A2 was identified as a causative gene for familial IBGC, and three mutations were reported in a northern Chinese population. Here, we aimed to explore the mutation spectrum of SLC20A2 in a southern Chinese population. Sanger sequencing was employed to screen mutations within SLC20A2 in two IBGC families and 14 sporadic IBGC cases from a southern Han Chinese population. Four novel mutations (c.82G>A p.D28N, c.185T>C p.L62P, c.1470_1478delGCAGGTCCT p.Q491_L493del and c.935-1G>A) were identified in two families and two sporadic cases, respectively; none were detected in 200 unrelated controls. No mutation was found in the remaining 12 patients. Different mutations may result in varied phenotypes, including brain calcification and clinical manifestations. Our study supports the hypothesis that SLC20A2 is a causative gene of IBGC and expands the mutation spectrum of SLC20A2, which facilitates the understanding of the genotype-phenotype correlation of IBGC.

Variants in the promoter region of CYP7A1 are associated with neuromyelitis optica but not with multiple sclerosis in the Han Chinese population.

Multiple sclerosis (MS) and neuromyelitis optica (NMO) are common autoimmune demyelinating disorders of the central nervous system. The exact etiology of each remains unclear. CYP7A1 was reported to be associated with NMO in Korean patients, but this is yet to be confirmed in other populations. In this study, we used Sanger sequencing to detect SNPs in the promoter region of CYP7A1 in a population consisting of unrelated patients and controls from the Han Chinese population (129 MS; 89 NMO; 325 controls). Two known SNPs, -204A>C (rs3808607) and -469T>C (rs3824260), and a novel SNP (-208G>C) were identified in the 5'-UTR of CYP7A1. The -204A>C was in complete linkage with -469T>C and both were associated with NMO but not with MS. Results suggest that the CYP7A1 allele was associated with NMO. NMO and MS have different genetic risk factors. This further supports the emerging evidence that MS and NMO are distinct disorders.

High frequency of Machado-Joseph disease identified in southeastern Chinese kindreds with spinocerebellar ataxia.

BACKGROUND: Machado-Joseph disease (MJD), caused by a CAG repeat expansion located in exon10 of the ATXN3 gene, is now regarded as one of the most common spinocerebellar ataxia (SCA) in the world. The relative frequency of MJD among SCA has previously been estimated at about 50% in the Chinese population and has been reported to be related to the frequency of large normal alleles in some populations. Taq polymerase has been used for PCR in nearly all studies reported previously. METHODS: Normal and expanded alleles of ATXN3 were detected via PCR using LA Taq DNA polymerase (better for GC-rich sequences) and denaturing polyacrylamide gel electrophoresis in 150 normal individuals and 138 unrelated probands from autosomal dominant SCA families. To compare reaction efficiency, 12 MJD patients' expanded alleles were amplified with La Taq and Taq polymerase respectively in the same amplifying systems and reaction conditions. RESULTS: Normal alleles ranged from 12 to 42 CAG repeats. The most common allele contained 14 repeats with a frequency of 23.3%, which corroborates previous reports. The frequency of large normal alleles (>27 repeats) was 0.28, which was very high relative to previous reports. The frequency of MJD in SCA patients was 72.5%, which was significantly higher than those in previous reports about the Chinese and other Asian populations. This frequency was one of the highest reported worldwide, with only Portuguese and Brazilian populations exhibiting higher proportions. All 12 expanded alleles were amplified in PCR with La Taq polymerase, whereas only 2 expanded alleles were amplified with Taq polymerase. CONCLUSION: We have first reported the highest relative frequency of MJD in Asia, and we attribute this high frequency to a more efficient PCR using LA Taq polymerase and hypothesized that large ANs may act as a reservoir for expanded alleles in the Southeastern Chinese population.

Association between novel TARDBP mutations and Chinese patients with amyotrophic lateral sclerosis.

BACKGROUND: TARDBP mutations have been reported in patients with amyotrophic lateral sclerosis (ALS) in different populations except Chinese. The present aim is to investigate the association between TARDBP mutations and Chinese patients with ALS. METHODS: 71 SALS patients and 5 FALS families with non-SOD1 mutations were screened for TARDBP mutations via direct sequencing. RESULTS: A novel heterozygous variation, Ser292Asn (875G>A), was identified in the proband and 4 asymptomatic relatives including the children of the dead patient from a FALS family. Thus the dead patient, the proband's brother, was speculated to carry Ser292Asn though his sample was unavailable to the detection. This variation was not found in 200 unrelated control subjects. A homology search of the TDP-43 protein in different species demonstrated that it was highly conserved. Also, it was predicted to be deleterious to protein function with SIFT-calculated probabilities of 0.00. Therefore, Ser292Asn is predicted to be a pathogenic mutation. In addition, we have found two silent mutations (Gly40Gly and Ala366Ala) and one novel polymorphism (239-18t>c). CONCLUSIONS: The present data have extended the spectrum of TARDBP mutations and polymorphisms, and supported the pathological role of TDP-43 in Chinese ALS patients.

A novel mutation in the senataxin gene identified in a Chinese patient with sporadic amyotrophic lateral sclerosis.

Our objective was to investigate the association between senataxin mutations and sporadic amyotrophic lateral sclerosis (ALS) in Chinese patients. DNA from 45 sporadic ALS patients was screened for mutations in senataxin using polymerase chain reaction (PCR) and direct sequencing. A novel variation, Thr1118Ile, was identified in a 42-year-old individual with sporadic ALS. This variation was not detected in 200 unrelated control individuals. In conclusion, the presence of this variation in a patient with sporadic ALS, and its absence in 200 controls, supports an association between senataxin and sporadic ALS. This study has broadened the mutation spectrum of senataxin and expanded the clinical phenotypes of senataxin mutations.

Novel mutation in the ABCA1 gene identified in a chinese patient with dementia and atherothrombotic cerebral infarction.

BACKGROUND: To date, 81 mutations of ATP-binding cassette transporter 1 (ABCA1) have been reported. However, no ABCA1 mutation has been reported in the Chinese population. METHODS: We used direct sequencing to screen for ABCA1 mutations in 72 patients with both atherosclerotic cerebral infarction (ACI) and plasma high-density lipoprotein cholesterol (HDL-C) < 0.8 mmol/l. The functionality of the mutation was verified using 200 unrelated controls and 76 patients with ACI and normal HDL-C by PCR-RFLP analysis. RESULTS: One patient with dementia prior to ACI was found to carry the heterozygous Y2206D mutation, which has not been reported previously. The patient had a medical history of atherosclerosis in the coronary and carotid arteries going back 40 years and splenohepatomegalia for 13 years, with a low plasma HDL-C level (0.66 mmol/l) and apolipoprotein A1 level (0.61 mmol/l). During the past decade, he had developed symptoms of dementia. Sixteen months prior to the study, he was admitted to hospital for an ACI. CONCLUSION: The results suggest that this patient is most likely a patient with familial hypoalphalipoproteinemia and that the Y2206D mutation may be associated with not only a lower level of HDL-C, but also with dementia.

Mutation analysis of 218 Chinese patients with Wilson disease revealed no correlation between the canine copper toxicosis gene MURR1 and Wilson disease.

Wilson disease (WD) is the most common disorder resulting in hepatic copper overload. A similar form of copper-associated cirrhosis caused by mutations of the canine copper toxicosis MURR1 gene is also observed in Bedlington terriers. Recent studies indicate that MURR1 might influence human copper metabolism and the clinical presentations of WD. However, the correlation between the MURR1 gene and the Chinese patients with WD has not been reported. In the present study, all three exons of the MURR1 gene including the intron-exon boundaries were directly sequenced in 120 unrelated healthy Chinese and 218 unrelated Chinese patients with WD. No mutations were detected in coding and splice site sequence in the human MURR1 gene. A novel polymorphism 3'+119T-->A in the 3' untranslated region (UTR) was identified in three healthy individuals and four patients with two disease-causing mutations in the ATP7B gene and a great diversity of clinical presentations. Of the ATP7B mutations reported here, Gly1268Arg is a novel one. Also, the previously described nucleotide change IVS2+63C-->G was detected in 31.66% of normal chromosomes and 26.15% of WD chromosomes. The results have indicated that there is no correlation between MURR1 and WD in the Chinese population.