The CGG repeat expansion in RILPL1 is associated with oculopharyngodistal myopathy type 4.

Recent studies indicate that CGG repeat expansions in LRP12, GIPC1, and NOTCH2NLC are associated with oculopharyngodistal myopathy (OPDM) types 1, 2, and 3, respectively. However, some clinicopathologically confirmed OPDM cases continue to have unknown genetic causes. Here, through a combination of long-read whole-genome sequencing (LRS), repeat-primed polymerase chain reaction (RP-PCR), and fluorescence amplicon length analysis PCR (AL-PCR), we found that a CGG repeat expansion in the 5' UTR of RILPL1 is associated with familial and simplex OPDM type 4 (OPDM4). The number of repeats ranged from 139 to 197. Methylation analysis indicates that the methylation levels in RILPL1 were unaltered in OPDM4 individuals. Analyses of muscle biopsies suggested that the expanded CGG repeat might be translated into a toxic poly-glycine protein that co-localizes with p62 in intranuclear inclusions. Moreover, analyses suggest that the toxic RNA gain-of-function effects also contributed to the pathogenesis of this disease. Intriguingly, all four types of OPDM have been found to be associated with the CGG repeat expansions located in 5' UTRs. This finding suggests that a common pathogenic mechanism, driven by the CGG repeat expansion, might underlie all cases of OPDM.

Multiomics analysis reveals serine catabolism as a potential therapeutic target for MELAS.

Mitochondrial disease is a devastating genetic disorder, with mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) and m.3243A>G being the most common phenotype and genotype, respectively. The treatment for MELAS patients is still less effective. Here, we performed transcriptomic and proteomic analysis in muscle tissue of MELAS patients, and discovered that the expression of molecules involved in serine catabolism were significantly upregulated, and serine hydroxymethyltransferase 2 (SHMT2) increased significantly in both the mRNA and protein levels. The SHMT2 protein level was also increased in myoblasts with m.3243A>G mutation, which was transdifferentiated from patients derived fibroblasts, accompanying with the decreased nicotinamide adenine dinucleotide (NAD+)/reduced NAD+ (NADH) ratio and cell viability. After treating with SHMT2 inhibitor (SHIN1), the NAD+/NADH ratio and cell viability in MELAS myoblasts increased significantly. Taken together, our study indicates that enhanced serine catabolism plays an important role in the pathogenesis of MELAS and that SHIN1 can be a potential small molecule for the treatment of this disease.

Non-coding CGG repeat expansion in LOC642361/NUTM2B-AS1 is associated with a phenotype of oculopharyngodistal myopathy.

BACKGROUND: Oculopharyngodistal myopathy (OPDM) is a rare adult-onset neuromuscular disease, associated with CGG repeat expansions in the 5' untranslated region of LRP12, GIPC1, NOTCH2NLC and RILPL1. However, the genetic cause of a proportion of pathoclinically confirmed cases remains unknown. METHODS: A total of 26 OPDM patients with unknown genetic cause(s) from 4 tertiary referral hospitals were included in this study. Clinical data and laboratory findings were collected. Muscle samples were observed by histological and immunofluorescent staining. Long-read sequencing was initially conducted in six patients with OPDM. Repeat-primed PCR was used to screen the CGG repeat expansions in LOC642361/NUTM2B-AS1 in all 26 patients. RESULTS: We identified CGG repeat expansion in the non-coding transcripts of LOC642361/NUTM2B-AS1 in another two unrelated Chinese cases with typical pathoclinical features of OPDM. The repeat expansion was more than 70 times in the patients but less than 40 times in the normal controls. Both patients showed no leucoencephalopathy but one showed mild cognitive impairment detected by Montreal Cognitive Assessment. Rimmed vacuoles and p62-positive intranuclear inclusions (INIs) were identified in muscle pathology, and colocalisation of CGG RNA foci with p62 was also found in the INIs of patient-derived fibroblasts. CONCLUSIONS: We identified another two unrelated cases with CGG repeat expansion in the long non-coding RNA of the LOC642361/NUTM2B-AS1 gene, presenting with a phenotype of OPDM. Our cases broadened the recognised phenotypic spectrum and pathogenesis in the disease associated with CGG repeat expansion in LOC642361/NUTM2B-AS1.

Novel TUBA4A variant causes congenital myopathy with focal myofibrillar disorganisation.

BACKGROUND: Congenital myopathies are a clinical, histopathological and genetic heterogeneous group of inherited muscle disorders that are defined on peculiar architectural abnormalities in the muscle fibres. Although there have been at least 33 different genetic causes of the disease, a significant percentage of congenital myopathies remain genetically unresolved. The present study aimed to report a novel TUBA4A variant in two unrelated Chinese patients with sporadic congenital myopathy. METHODS: A comprehensive strategy combining laser capture microdissection, proteomics and whole-exome sequencing was performed to identify the candidate genes. In addition, the available clinical data, myopathological changes, the findings of electrophysiological examinations and thigh muscle MRIs were also reviewed. A cellular model was established to assess the pathogenicity of the TUBA4A variant. RESULTS: We identified a recurrent novel heterozygous de novo c.679C>T (p.L227F) variant in the TUBA4A (NM_006000), encoding tubulin alpha-4A, in two unrelated patients with clinicopathologically diagnosed sporadic congenital myopathy. The prominent myopathological changes in both patients were muscle fibres with focal myofibrillar disorganisation and rimmed vacuoles. Immunofluorescence showed ubiquitin-positive TUBA4A protein aggregates in the muscle fibres with rimmed vacuoles. Overexpression of the L227F mutant TUBA4A resulted in cytoplasmic aggregates which colocalised with ubiquitin in cellular model. CONCLUSION: Our findings expanded the phenotypic and genetic manifestations of TUBA4A as well as tubulinopathies, and added a new type of congenital myopathy to be taken into consideration in the differential diagnosis.

CGG repeat expansion in NOTCH2NLC causes mitochondrial dysfunction and progressive neurodegeneration in Drosophila model.

Neuronal intranuclear inclusion disease (NIID) is a neuromuscular/neurodegenerative disease caused by the expansion of CGG repeats in the 5' untranslated region (UTR) of the NOTCH2NLC gene. These repeats can be translated into a polyglycine-containing protein, uN2CpolyG, which forms protein inclusions and is toxic in cell models, albeit through an unknown mechanism. Here, we established a transgenic Drosophila model expressing uN2CpolyG in multiple systems, which resulted in progressive neuronal cell loss, locomotor deficiency, and shortened lifespan. Interestingly, electron microscopy revealed mitochondrial swelling both in transgenic flies and in muscle biopsies of individuals with NIID. Immunofluorescence and immunoelectron microscopy showed colocalization of uN2CpolyG with mitochondria in cell and patient samples, while biochemical analysis revealed that uN2CpolyG interacted with a mitochondrial RNA binding protein, LRPPRC (leucine-rich pentatricopeptide repeat motif-containing protein). Furthermore, RNA sequencing (RNA-seq) analysis and functional assays showed down-regulated mitochondrial oxidative phosphorylation in uN2CpolyG-expressing flies and NIID muscle biopsies. Finally, idebenone treatment restored mitochondrial function and alleviated neurodegenerative phenotypes in transgenic flies. Overall, these results indicate that transgenic flies expressing uN2CpolyG recapitulate key features of NIID and that reversing mitochondrial dysfunction might provide a potential therapeutic approach for this disorder.

Pathologic changes in neuronal intranuclear inclusion disease are linked to aberrant FUS interaction under hyperosmotic stress.

CGG repeat expansion in NOTCH2NLC is the genetic cause of neuronal intranuclear inclusion disease (NIID). Previous studies indicated that the CGG repeats can be translated into polyglycine protein (N2CpolyG) which was toxic to neurons by forming intranuclear inclusions (IIs). However, little is known about the factors governing polyG IIs formation as well as its molecular pathogenesis. Considering that neurogenetic disorders usually involve interactions between genetic and environmental stresses, we investigated the effect of stress on the formation of IIs. Our results revealed that under hyperosmotic stress, N2CpolyG translocated from the cytoplasm to the nucleus and formed IIs in SH-SY5Y cells, recapitulating the pathological hallmark of NIID patients. Furthermore, N2CpolyG interacted/ co-localized with an RNA-binding protein FUS in the IIs of cellular model and NIID patient tissues, thereby disrupting stress granule formation in cytoplasm under hyperosmotic stress. Consequently, dysregulated expression of microRNAs was found both in NIID patients and cellular model, which could be restored by FUS overexpression in cultured cells. Overall, our findings indicate a mechanism of stress-induced pathological changes as well as neuronal damage, and a potential strategy for the treatment of NIID.

Encephalitis-like episodes with cortical edema and enhancement in patients with neuronal intranuclear inclusion disease.

OBJECTIVES: Neuronal intranuclear inclusion disease (NIID) exhibited significant clinical heterogeneities. However, the clinical features, radiographic changes, and prognosis of patients with encephalitis-like NIID have yet to be systematically elucidated. METHODS: Clinical data including medical history, physical examination, and laboratory examinations were collected and analyzed. Skin and sural nerve biopsies were conducted on the patient. Repeat-primed PCR (RP-PCR) and fluorescence amplicon length PCR (AL-PCR) were used to detect the expansion of CGG repeat. We also reviewed the clinical and genetic data of NIID patients with cortical enhancement. RESULTS: A 54-year-old woman presented with encephalitis-like NIID, characterized by severe headache and agitative psychiatric symptoms. The brain MRI showed cortical swelling in the temporo-occipital lobes and significant enhancement of the cortical surface and dura, but without hyperintensities along the corticomedullary junction on diffusion-weighted image (DWI). A biopsy of the sural nerve revealed a demyelinating pathological change. The intranuclear inclusions were detected in nerve and skin tissues using the p62 antibody and electron microscopy. RP-PCR and AL-PCR unveiled the pathogenic expansion of CGG repeats in the NOTCH2NLC gene. A review of the literature indicated that nine out of the 16 patients with cortical lesions and linear enhancement exhibited encephalitis-like NIID. CONCLUSION: This study indicated that patients with encephalitis-like NIID typically exhibited headache and excitatory psychiatric symptoms, often accompanied by cortical edema and enhancement of posterior lobes, and responded well to glucocorticoid treatment. Furthermore, some patients may not exhibit hyperintensities along the corticomedullary junction on DWI, potentially leading to misdiagnosis.

Novel mutations in FLVCR1 cause tremors, sensory neuropathy with retinitis pigmentosa.

The mutations of the feline leukemia virus subgroup C receptor-related protein 1 (FLVCR1) cause ataxia with retinitis pigmentosa. Recent studies indicated a large variation in the phenotype of FLVCR1-associated diseases. In this report, we describe an adult male who manifested first with tremors in his third decade, followed by retinitis pigmentosa, sensory ataxia, and sensory neuropathy in his fourth decade. While retinitis pigmentosa and sensory ataxia are well-recognized features of FLVCR1-associated disease, tremor is rarely described. Whole-exome sequencing revealed novel compound heterozygous pathogenic FLVCR1 variants: c.498 G > A; p.(Trp166*) and c.369 T > G; p.(Phe123Leu). In addition, we have highlighted the ultrastructural abnormalities of the sural biopsy in this patient.

Aquaporin 4 Mediates the Effect of Iron Overload on Hydrocephalus After Intraventricular Hemorrhage.

BACKGROUND: Iron overload plays an important role in hydrocephalus development following intraventricular hemorrhage (IVH). Aquaporin 4 (AQP4) participates in the balance of cerebrospinal fluid secretion and absorption. The current study investigated the role of AQP4 in the formation of hydrocephalus caused by iron overload after IVH. METHODS: There were three parts to this study. First, Sprague-Dawley rats received an intraventricular injection of 100 µl autologous blood or saline control. Second, rats had IVH and were treated with deferoxamine (DFX), an iron chelator, or vehicle. Third, rats had IVH and were treated with 2-(nicotinamide)-1,3,4-thiadiazole (TGN-020), a specific AQP4 inhibitor, or vehicle. Rats underwent T2-weighted and T2* gradient-echo magnetic resonance imaging to assess lateral ventricular volume and intraventricular iron deposition at 7, 14, and 28 days after intraventricular injection and were then euthanized. Real-time quantitative polymerase chain reaction, western blot analysis, and immunofluorescence analyses were conducted on the rat brains to evaluate the expression of AQP4 at different time points. Hematoxylin and eosin-stained brain sections were obtained to assess the ventricular wall damage on day 28. RESULTS: Intraventricular injection of autologous blood caused a significant ventricular dilatation, iron deposition, and ventricular wall damage. There was increased AQP4 mRNA and protein expression in the periventricular tissue in IVH rats through day 7 to day 28. The DFX treatment group had a lower lateral ventricular volume and less intraventricular iron deposition and ventricular wall damage than the vehicle-treated group after IVH. The expression of AQP4 protein in periventricular tissue was also inhibited by DFX on days 14 and 28 after IVH. The use of TGN-020 attenuated hydrocephalus development after IVH and inhibited the expression of AQP4 protein in the periventricular tissue between day 14 and day 28 without a significant effect on intraventricular iron deposition or ventricular wall damage. CONCLUSIONS: AQP4 located in the periventricular area mediated the effect of iron overload on hydrocephalus after IVH.

Expansion of GGC Repeat in GIPC1 Is Associated with Oculopharyngodistal Myopathy.

Oculopharyngodistal myopathy (OPDM) is an adult-onset inherited neuromuscular disorder characterized by progressive ptosis, external ophthalmoplegia, and weakness of the masseter, facial, pharyngeal, and distal limb muscles. The myopathological features are presence of rimmed vacuoles (RVs) in the muscle fibers and myopathic changes of differing severity. Inheritance is variable, with either putative autosomal-dominant or autosomal-recessive pattern. Here, using a comprehensive strategy combining whole-genome sequencing (WGS), long-read whole-genome sequencing (LRS), linkage analysis, repeat-primed polymerase chain reaction (RP-PCR), and fluorescence amplicon length analysis polymerase chain reaction (AL-PCR), we identified an abnormal GGC repeat expansion in the 5' UTR of GIPC1 in one out of four families and three sporadic case subjects from a Chinese OPDM cohort. Expanded GGC repeats were further confirmed as the cause of OPDM in an additional 2 out of 4 families and 6 out of 13 sporadic Chinese individuals with OPDM, as well as 7 out of 194 unrelated Japanese individuals with OPDM. Methylation, qRT-PCR, and western blot analysis indicated that GIPC1 mRNA levels were increased while protein levels were unaltered in OPDM-affected individuals. RNA sequencing indicated p53 signaling, vascular smooth muscle contraction, ubiquitin-mediated proteolysis, and ribosome pathways were involved in the pathogenic mechanisms of OPDM-affected individuals with GGC repeat expansion in GIPC1. This study provides further evidence that OPDM is associated with GGC repeat expansions in distinct genes and highly suggests that expanded GGC repeat units are essential in the pathogenesis of OPDM, regardless of the genes in which the expanded repeats are located.

CAG Repeat Expansion in THAP11 Is Associated with a Novel Spinocerebellar Ataxia.

BACKGROUND: More than 50 loci are associated with spinocerebellar ataxia (SCA), and the most frequent subtypes share nucleotide repeats expansion, especially CAG expansion. OBJECTIVE: The objective of this study was to confirm a novel SCA subtype caused by CAG expansion. METHODS: We performed long-read whole-genome sequencing combined with linkage analysis in a five-generation Chinese family, and the finding was validated in another pedigree. The three-dimensional structure and function of THAP11 mutant protein were predicted. Polyglutamine (polyQ) toxicity of THAP11 gene with CAG expansion was assessed in skin fibroblasts of patients, human embryonic kidney 293 and Neuro-2a cells. RESULTS: We identified THAP11 as the novel causative SCA gene with CAG repeats ranging from 45 to 100 in patients with ataxia and from 20 to 38 in healthy control subjects. Among the patients, the number of CAA interruptions within CAG repeats was decreased to 3 (up to 5-6 in controls), whereas the number of 3' pure CAG repeats was up to 32 to 87 (4-16 in controls), suggesting that the toxicity of polyQ protein was length dependent on the pure CAG repeats. Intracellular aggregates were observed in cultured skin fibroblasts from patients. THAP11 polyQ protein was more intensely distributed in the cytoplasm of cultured skin fibroblasts from patients, which was replicated with in vitro cultured neuro-2a transfected with 54 or 100 CAG repeats. CONCLUSIONS: This study identified a novel SCA subtype caused by intragenic CAG repeat expansion in THAP11 with intracellular aggregation of THAP11 polyQ protein. Our findings extended the spectrum of polyQ diseases and offered a new perspective in understanding polyQ-mediated toxic aggregation. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Subclinical peripheral neuropathy is common in neuronal intranuclear inclusion disease with dominant encephalopathy.

BACKGROUND AND PURPOSE: Neuronal intranuclear inclusion disease (NIID) is associated with CGG repeat expansion in the NOTCH2NLC gene. Although pure or dominant peripheral neuropathy has been described as a subtype of NIID in a few patients, most NIID patients predominantly show involvements of the central nervous system (CNS). It is necessary to further explore whether these patients have subclinical peripheral neuropathy. METHODS: Twenty-eight NIID patients, clinically characterized by CNS-dominant involvements, were recruited from two tertiary hospitals. Standard nerve conduction studies were performed in all patients. Skin and sural nerve biopsies were performed in 28 and 15 patients, respectively. Repeat-primed polymerase chain reaction and amplicon length polymerase chain reaction were used to screen the CGG repeat expansion in NOTCH2NLC. RESULTS: All 28 patients can be diagnosed with NIID based on skin pathological and genetic changes. All patients predominantly showed CNS symptoms mainly characterized by episodic encephalopathy and cognitive impairments, but no clinical symptoms of peripheral neuropathy could be observed initially. Electrophysiological abnormalities were found in 96.4% (27/28) of these patients, indicating that subclinical peripheral neuropathy is common in NIID patients with CNS-dominant type. Electrophysiological and neuropathological studies revealed that demyelinating degeneration was the main pathological pattern in these patients, although mild axonal degeneration was also observed in some patients. No significant association between CGG repeat size and the change of nerve conduction velocity was found in these patients. CONCLUSIONS: This study demonstrated that most patients with CNS-dominant NIID had subclinical peripheral neuropathy. Electrophysiological examination should be the routinely diagnostic workflow for every NIID patient.

Genetic origin of sporadic cases and RNA toxicity in neuronal intranuclear inclusion disease.

BACKGROUND: GGC repeat expansion in NOTCH2NLC has been recently linked to neuronal intranuclear inclusion disease (NIID) via unknown disease mechanisms. Herein, we explore the genetic origin of the sporadic cases and toxic RNA gain-of-function mechanism in NIID. METHODS: Multiple genetic screenings were performed on NIID individuals and their available family members. Methylation status of blood DNA, NOTCH2NLC mRNA level from muscle biopsies and RNA foci from skin biopsies of NIID individuals or asymptomatic carriers were evaluated and compared. RESULTS: In two sporadic NIID families, we identified two clinically and pathologically asymptomatic fathers carrying large GGC repeat expansion, above 300 repeats, with offspring repeat numbers of 172 and 148, respectively. Further evaluation revealed that the GGC repeat numbers in the sperm from two asymptomatic fathers were only 63 and 98, respectively. The CpG island in NOTCH2NLC of the asymptomatic carriers was hypermethylated, and accordingly, the NOTCH2NLC mRNA levels were decreased in the asymptomatic fathers. GGC repeat expansion RNA formed RNA foci and sequestered RNA binding proteins into p62 positive intranuclear inclusions in NIID individuals but not in the control or asymptomatic carrier. CONCLUSION: Our study suggested the GGC repeat expansion in NOTCH2NLC might have a disease-causing number ranging from ~41 to ~300 repeats. The contraction of GGC repeat expansion in sperm could be a possible mechanism for the paternal-biased origin in some sporadic or recessive inherited NIID individuals. The toxic RNA gain-of-function mechanism was identified to be involved in the pathogenicity of this disease.

Oculopharyngodistal myopathy.

PURPOSE OF REVIEW: Oculopharyngodistal myopathy (OPDM) is a rare adolescent or adult-onset neuromuscular disease that is characterized by progressive ocular, facial, pharyngeal and distal limb muscle weakness. The rimmed vacuoles and intranuclear inclusions in myofibers constitute the pathological hallmark of OPDM. In this review, the latest findings related to the genetic, molecular and clinical features of OPDM, as well as the diagnosis and management are summarized. RECENT FINDINGS: Four gene mutations, CGG repeats in the 5'-untranslated region of LRP12 , GIPC1 , NOTCH2NLC and RILPL1 have been reported to be disease-causing genes in OPDM, namely OPDM1, OPDM2, OPDM3 and OPDM4, accordingly. So far, limited studies have suggested that CGG repeat expansion within the pathogenic range may play a key role in the pathogenesis of OPDM with the gain-of-function mechanism at the RNA and/or protein level, while repeat expansion over a threshold limit may cause hypermethylation, leading to the transcriptional silencing of the CGG repeats in the expanded allele, which results in the existence of mild phenotype or asymptomatic carriers. SUMMARY: Novel gene mutations, possible molecular mechanisms and the clinical features related to different causative genes are discussed in this review. More studies on the exact pathogenic mechanism are needed.

DNA2 mutation causing multisystemic disorder with impaired mitochondrial DNA maintenance.

PURPOSE: To describe a novel DNA2 variant contributing to defects in mtDNA maintenance and mtDNA depletion syndrome (MDS), and the clinical and histological findings associated with this variation. METHODS: Herein, we describe the case of a patient who presented with hearing loss and myopathy, given the family history of similar findings in the father, was evaluated by sequencing of the deafness gene panel, mitochondrial genome, and the exome. Furthermore, tissue staining, mtDNA copy number detection, mtDNA sequencing, and long-range polymerase chain reaction tests were also conducted on the muscle biopsy specimen. In vitro experiments, including analyses of the mtDNA copy number; levels of ATP, ATPase, and reactive oxygen species (ROS); and the membrane potential, were performed. RESULTS: The DNA2 heterozygous truncating variant c. 2368C > T (p.Q790X) was identified and verified as the cause of an mtDNA copy number decrement in both functional experiments and muscle tissue analyses. These changes were accompanied by reductions in ATP, ATPase, and ROS levels. CONCLUSION: The DNA2 variant was a likely cause of MDS in this patient. These findings expand the mutational spectrum of MDS and improve our understanding of the functions of DNA2 by revealing its novel role in mtDNA maintenance.

Diagnostic Value of Salivary Real-Time Quaking-Induced Conversion in Parkinson's Disease and Multiple System Atrophy.

BACKGROUND: Aggregation of α-synuclein (oligomeric α-syn) has been considered as the pathological hallmark of Parkinson's disease (PD) and multiple system atrophy (MSA). Studies showed oligomeric α-syn/total α-syn ratio was increased in the saliva of patients with PD, suggesting that seeding activity of salivary oligomeric α-syn may be a novel biomarker for the diagnosis of PD and MSA. OBJECTIVE: This study aimed to evaluate the diagnostic value of salivary α-syn seeding activity in patients with PD and MSA. METHODS: A total of 75 patients with PD, 18 patients with MSA, and 36 nonneurodegenerative healthy control subjects underwent salivary α-syn real-time quaking-induced conversion (RT-QuIC) assay. RESULTS: Salivary α-syn RT-QuIC assay distinguished patients with PD with 76.0% sensitivity (95% confidence interval [CI], 66.1-85.9) and 94.4% specificity (95% CI, 86.6-100.0). RT-QuIC assay sensitivity reached 61.1% (95% CI, 36.2-86.1) in patients with MSA. No significant differences were observed in the diameter of salivary α-syn fibrils examined by electron microscopy and in thioflavin T fluorescence intensity of salivary α-syn fibrils detected by RT-QuIC assay between patients with PD and MSA. Notably, the lag phase of RT-QuIC assay from patients with PD was significantly shorter than that of patients with MSA, which might be clinically applicable to the discrimination between PD and MSA. CONCLUSIONS: Salivary α-syn seeding activity may serve as a novel biomarker for the clinical diagnosis of PD and MSA.© 2022 International Parkinson and Movement Disorder Society © 2022 International Parkinson and Movement Disorder Society.

Sporadic adult-onset neuronal intranuclear inclusion disease without high-intensity signal on DWI and T2WI: a case report.

BACKGROUND: Neuronal intranuclear inclusion disease (NIID) is a rare neurodegenerative disease characterized by eosinophilic hyaline intranuclear inclusions in cells in the central and peripheral nervous system. High-intensity signal in the corticomedullary junction on diffusion-weighted imaging (DWI) is supportive to the diagnosis of NIID. We describe a patient with sporadic adult-onset NIID but without any high-intensity signal on DWI and T2-weighted imaging (T2WI). CASE PRESENTATION: A 58-year-old woman without special family history developed mild persistent tremor in the right hand and deteriorated 2 years later. At 60 years of age, the patient began to conceive the bank, police and internet being deceptive, further presented apathy and confusion after two and a half years, as well as fabrication of non-existent things. Despite the treatment of antipsychotic drugs due to a diagnosis of mental disorder, the patient appeared weakness in the right limbs. Neurological examination revealed mutism, resting tremor, cogwheel-like rigidity in upper limbs, and weakness in all limbs. Brain magnetic resonance imaging displayed no cerebral atrophy initially but atrophy of frontal, temporal and parietal lobes 5 years later. No any high-intensity signal on DWI and T2WI was revealed. However, hypometabolism in the cortexes with atrophy and the right putamen nucleus were showed on 18F-fluoro-deoxy-glucose positron emission tomography/magnetic resonance. On the basis of 107 GGC repeats (normal number <40) in NOTCH2NLC gene and intranuclear inclusions with p62 immunoreactivity in the adipocyte of cutaneous sweat duct by skin biopsy, NIID was finally diagnosed. The symptomatic treatment was given but the patient had no evident improvement. CONCLUSIONS: Our case highlights that despite the lack of high-intensity signal on DWI and T2WI, NIID is still considered for patients with parkinsonism and mental impairment.

The Th17/Treg cell balance: crosstalk among the immune system, bone and microbes in periodontitis.

Periodontopathic bacteria constantly stimulate the host, which causes an immune response, leading to host-induced periodontal tissue damage. The complex interaction and imbalance between Th17 and Treg cells may be critical in the pathogenesis of periodontitis. Furthermore, the RANKL/RANK/OPG system plays a significant role in periodontitis bone metabolism, and its relationship with the Th17/Treg cell imbalance may be a bridge between periodontal bone metabolism and the immune system. This article reviews the literature related to the Th17/Treg cell imbalance mediated by pathogenic periodontal microbes, and its mechanism involving RANKL/RANK/OPG in periodontitis bone metabolism, in an effort to provide new ideas for the study of the immunopathological mechanism of periodontitis.

The GGC repeat expansion in NOTCH2NLC is associated with oculopharyngodistal myopathy type 3.

Oculopharyngodistal myopathy (OPDM) is an adult-onset neuromuscular disease characterized by progressive ocular, facial, pharyngeal and distal limb muscle involvement. Trinucleotide repeat expansions in LRP12 or GIPC1 were recently reported to be associated with OPDM. However, a significant portion of OPDM patients have unknown genetic causes. In this study, long-read whole-genome sequencing and repeat-primed PCR were performed and we identified GGC repeat expansions in the NOTCH2NLC gene in 16.7% (4/24) of a cohort of Chinese OPDM patients, designated as OPDM type 3 (OPDM3). Methylation analysis indicated that methylation levels of the NOTCH2NLC gene were unaltered in OPDM3 patients, but increased significantly in asymptomatic carriers. Quantitative real-time PCR analysis indicated that NOTCH2NLC mRNA levels were increased in muscle but not in blood of OPDM3 patients. Immunofluorescence on OPDM muscle samples and expressing mutant NOTCH2NLC with (GGC)69 repeat expansions in HEK293 cells indicated that mutant NOTCH2NLC-polyglycine protein might be a major component of intranuclear inclusions, and contribute to toxicity in cultured cells. In addition, two RNA-binding proteins, hnRNP A/B and MBNL1, were both co-localized with p62 in intranuclear inclusions in OPDM muscle samples. These results indicated that a toxic protein gain-of-function mechanism and RNA gain-of-function mechanism may both play a vital role in the pathogenic processes of OPDM3. This study extended the spectrum of NOTCH2NLC repeat expansion-related diseases to a predominant myopathy phenotype presenting as OPDM, and provided evidence for possible pathogenesis of these diseases.

A novel compound heterozygous mutation in the COA7 gene responsible for a Chinese patient with spinocerebellar ataxia with axonal neuropathy type 3.

OBJECTIVE: Spinocerebellar ataxia with axonal neuropathy type 3 (SCAN3) is a very rare autosomal recessive hereditary disease. Mutations in the COA7 gene, which encodes cytochrome c oxidase assembly factor 7, have been recently reported as the causative gene of SCAN3. So far, only five SCAN3 patients with COA7 mutations have been documented. Herein, we report the clinical, electrophysiological, histological, and genetic findings of a Chinese patient with SCAN3. MATERIALS AND METHODS: The patient was a 31-year-old woman who presented with early-onset peripheral neuropathy and progressive ataxia. She was asked about her medical history and underwent electrophysiological examination, nerve and muscle biopsy, and gene detection. RESULTS: Whole exome next-generation sequencing identified a novel compound heterozygous mutation of COA7 (c.17A>G p.D6G; c.554G>A, p.W185*) in this patient. Magnetic resonance imaging showed cerebellum and spinal cord atrophy. Nerve conduction studies and sural nerve biopsies revealed sensorimotor axonal neuropathy. Muscle biopsies showed mitochondrial abnormalities. Respiratory chain enzyme assay of skin fibroblasts showed normal respiratory chain complex activities. Additionally, the clinical data on previously reported SCAN patients with identified genetic causes in PubMed was summarized. Compared with SCAN1 and SCAN2 patients, SCAN3 patients had earlier onset age, less cognitive impairment, and no ocular signs. CONCLUSION: We reported the first patient diagnosed with SCAN3 in China. A novel mutation in the gene COA7 (c.554G>A, p.W185*) expanded the genetic spectrum of the disease.