Neuronal intranuclear hyaline inclusion disease showing motor-sensory and autonomic neuropathy

Review of Phenotypic Heterogeneity of Neuronal Intranuclear Inclusion Disease and NOTCH2NLC-Related GGC Repeat Expansion Disorders

Neuronal intranuclear inclusion disease (NIID) is an underdiagnosed neurodegenerative disorder caused by pathogenic GGC expansions in NOTCH2NLC. However, an increasing number of reports of NOTCH2NLC GGC expansions in patients with Alzheimer disease, essential tremor, Parkinson disease, amyotrophic lateral sclerosis, and oculopharyngodistal myopathy have led to the proposal of a new concept known as NOTCH2NLC-related GGC repeat expansion disorders (NREDs). The majority of studies have mainly focused on screening for NOTCH2NLC GGC repeat variation in populations previously diagnosed with the associated disease, subsequently presenting it as a novel causative gene for the condition. These studies appear to be clinically relevant but do have their limitations because they may incorrectly regard the lack of MRI abnormalities as an exclusion criterion for NIID or overlook concomitant clinical presentations not typically observed in the associated diseases. Besides, in many instances within these reports, patients lack pathologic evidence or undergo long-term follow-up to conclusively rule out NIID. In this review, we will systematically review the research on NOTCH2NLC 5' untranslated region GGC repeat expansions and their association with related neurologic disorders, explaining the limitations of the relevant reports. Furthermore, we will integrate subsequent studies to further demonstrate that these patients actually experienced distinct clinical phenotypes of NIID.

Utility of labial salivary gland biopsy in the histological diagnosis of neuronal intranuclear inclusion disease

BACKGROUND AND PURPOSE

Neuronal intranuclear inclusion disease (NIID) poses a diagnostic challenge because of its diverse clinical manifestations. Detection of intranuclear inclusions remains the primary diagnostic criterion for NIID. Skin biopsies have traditionally been used, but concerns exist regarding postoperative complications and scarring. We sought to investigate the diagnostic utility of labial salivary gland biopsy, a less invasive alternative.

METHODS

This study included a total of 19 patients and 11 asymptomatic carriers who underwent labial gland biopsies, while 10 patients opted for skin biopsies. All these individuals were confirmed to have pathogenic GGC repeat expansions in the NOTCH2NLC gene. The control group comprised 20 individuals matched for age and sex, all with nonpathogenic GGC repeat expansions, and their labial gland tissue was sourced from oral surgery specimens.

RESULTS

Labial gland biopsies proved to be a highly effective diagnostic method in detecting eosinophilic intranuclear inclusions in NIID patients. The inclusions showed positive staining for p62 and ubiquitin, confirming their pathological significance. The presence of uN2CpolyG protein in the labial gland tissue further supported the diagnosis. Importantly, all patients who underwent lip gland biopsy experienced fast wound healing without any noticeable scarring. In contrast, skin biopsies led to varying degrees of scarring and one instance of a localized infection.

CONCLUSION

Labial salivary gland biopsy emerged as a minimally invasive, efficient diagnostic method for NIID, with rapid healing and excellent sensitivity.

Not your usual neurodegenerative disease: a case report of neuronal intranuclear inclusion disease with unconventional imaging patterns

Background

Neuronal intranuclear inclusion disease (NIID) is a rare neurodegenerative illness with characteristic brain magnetic resonance imaging (MRI) manifestations: diffuse symmetric white-matter hyperintensities in lateral cerebral ventricle areas in fluid-attenuated inversion recovery (FLAIR) and high-intensity signals along the corticomedullary junction of the frontal-parietal-temporal lobes in diffusion weighted imaging (DWI). Here, we report a case of adult-onset NIID who was misdiagnosed with Susac syndrome (SS) due to unusual corpus callosum imaging findings.

Case presentation

A 39-year-old man presented with chronic headache, blurred vision, tinnitus, and numbness in the hands as initial symptoms, accompanied by cognitive slowing and decreased memory. Brain MRI revealed round hypointense lesions on T1-weighted imaging (T1WI) and hyperintense lesions on T2WI/FLAIR/DWI in the genu and splenium of the corpus callosum. An initial diagnosis of SS was made based on the presence of the SS-typical symptoms and SS-characteristic radiology changes. Furthermore, the patient's symptoms improved upon completion of a combined pharmacotherapy plan. However, no significant changes were evident 18 months after the brain MRI scan. Eventually, the patient was then diagnosed with NIID based on a skin biopsy and detection of expanded GGC (guanine, guanine, cytosine) repeats in the NOTCH2NLC gene.

Conclusion

The present NIID case in which there was simultaneous onset of altered nervous and visual system functioning and atypical imaging findings, the atypical imaging findings may reflect an initial change of NIID leukoencephalopathy.

Clinical phenotypic diversity of NOTCH2NLC-related disease in the largest case series of inherited peripheral neuropathy in Japan

BACKGROUND

NOTCH2NLC GGC repeat expansions have been associated with various neurogenerative disorders, including neuronal intranuclear inclusion disease and inherited peripheral neuropathies (IPNs). However, only a few NOTCH2NLC-related disease studies in IPN have been reported, and the clinical and genetic spectra remain unclear. Thus, this study aimed to describe the clinical and genetic manifestations of NOTCH2NLC-related IPNs.

METHOD

Among 2692 Japanese patients clinically diagnosed with IPN/Charcot-Marie-Tooth disease (CMT), we analysed NOTCH2NLC repeat expansion in 1783 unrelated patients without a genetic diagnosis. Screening and repeat size determination of NOTCH2NLC repeat expansion were performed using repeat-primed PCR and fluorescence amplicon length analysis-PCR.

RESULTS

NOTCH2NLC repeat expansions were identified in 26 cases of IPN/CMT from 22 unrelated families. The mean median motor nerve conduction velocity was 41 m/s (range, 30.8-59.4), and 18 cases (69%) were classified as intermediate CMT. The mean age of onset was 32.7 (range, 7-61) years. In addition to motor sensory neuropathy symptoms, dysautonomia and involuntary movements were common (44% and 29%). Furthermore, the correlation between the age of onset or clinical symptoms and the repeat size remains unclear.

CONCLUSIONS

These findings of this study help us understand the clinical heterogeneity of NOTCH2NLC-related disease, such as non-length-dependent motor dominant phenotype and prominent autonomic involvement. This study also emphasise the importance of genetic screening, regardless of the age of onset and type of CMT, particularly in patients of Asian origin, presenting with intermediate conduction velocities and dysautonomia.

Characteristics of autonomic dysfunction in neuronal intranuclear inclusion disease

Background

This study aimed to investigate the features of autonomic dysfunction (AutD) in a large cohort of patients with neuronal intranuclear inclusion disease (NIID).

Methods

A total of 122 patients with NIID and 122 controls were enrolled. All participants completed the Scales for Outcomes in Parkinson's Disease-Autonomic Questionnaire (SCOPA-AUT) and genetic screening for GGC expanded repeats within the NOTCH2NLC gene. All patients underwent neuropsychological and clinical assessments. SCOPA-AUT was performed to compare AutD between patients and controls. The associations between AutD and disease-related characteristics of NIID were studied.

Results

94.26% of patients had AutD. Compared with controls, patients had more severe AutD in total SCOPA-AUT, gastrointestinal, urinary, cardiovascular, thermoregulatory, pupillomotor and sexual domains (all p < 0.05). The area under the curve (AUC) value for the total SCOPA-AUT (AUC = 0.846, sensitivity = 69.7%, specificity = 85.2%, cutoff value = 4.5) was high in differentiating AtuD of patients with NIID from controls. The total SCOPA-AUT was significantly and positively associated with age (r = 0.185, p = 0.041), disease duration (r = 0.207, p = 0.022), Neuropsychiatric Inventory (NPI) (r = 0.446, p < 0.01), and Activities of Daily Living (ADL) (r = 0.390, p < 0.01). Patients with onset-of-AutD had higher SCOPA-AUT scores than patients without onset-of-AutD (p < 0.001), especially in the urinary system (p < 0.001) and male sexual dysfunction (p < 0.05).

Conclusion

SCOPA-AUT can be used as a diagnostic and quantitative tool for autonomic dysfunction in NIID. The high prevalence of AutD in patients suggests that NIID diagnosis should be considered in patients with AutD, especially in those with unexplained AutD alone. AutD in patients is related to age, disease duration, impairment of daily living ability, and psychiatric symptoms.

NOTCH2NLC GGC repeat expansion causes retinal pathology with intranuclear inclusions throughout the retina and causes visual impairment

The retinal pathology of genetically confirmed neuronal intranuclear inclusion disease (NIID) is yet unknown. We report the ocular findings in four NIID patients with NOTCH2NLC GGC repeat expansion to investigate the pathology of retinopathy. All four NIID patients were diagnosed by skin biopsy and NOTCH2NLC GGC repeat analysis. Ocular findings in patients with NIID were studied using fundus photographs, optical coherence tomographic images (OCT), and full-field electroretinograms (ERGs). The histopathology of the retina was studied on autopsy samples from two cases with immunohistochemistry. All patients had an expansion of the GGC repeat (87-134 repeats) in the NOTCH2NLC. Two patients were legally blind and had been diagnosed with retinitis pigmentosa prior to the diagnosis of NIID and assessed with whole exome sequencing to rule out comorbidity with other retinal diseases. Fundus photographs around the posterior pole showed chorioretinal atrophy in the peripapillary regions. OCT showed thinning of the retina. ERGs showed various abnormalities in cases. The histopathology of autopsy samples showed diffusely scattered intranuclear inclusions throughout the retina from the retinal pigment epithelium to the ganglion cell layer, and optic nerve glial cells. And severe gliosis was observed in retina and optic nerve. The NOTCH2NLC GGC repeat expansion causes numerous intranuclear inclusions in the retina and optic nerve cells and gliosis. Visual dysfunction could be the first sign of NIID. We should consider NIID as one of the causes of retinal dystrophy and investigate the GGC repeat expansion in NOTCH2NLC.

Current advances in neuronal intranuclear inclusion disease

Neuronal intranuclear inclusion disease (NIID) is a rare but probably underdiagnosed neurodegenerative disorder due to pathogenic GGC expansions in the NOTCH2NLC gene. In this review, we summarize recent developments in the inheritance features, pathogenesis, and histopathologic and radiologic features of NIID that subvert the previous perceptions of NIID. GGC repeat sizes determine the age of onset and clinical phenotypes of NIID patients. Anticipation may be absent in NIID but paternal bias is observed in NIID pedigrees. Eosinophilic intranuclear inclusions in skin tissues once considered pathological hallmarks of NIID can also present in other GGC repeat diseases. Diffusion-weighted imaging (DWI) hyperintensity along the corticomedullary junction once considered the imaging hallmark of NIID can frequently be absent in muscle weakness and parkinsonism phenotype of NIID. Besides, DWI abnormalities can appear years after the onset of predominant symptoms and may even disappear completely with disease progression. Moreover, continuous reports of NOTCH2NLC GGC expansions in patients with other neurodegenerative diseases lead to the proposal of a new concept of NOTCH2NLC-related GGC repeat expansion disorders (NRED). However, by reviewing the previous literature, we point out the limitations of these studies and provide evidence that these patients are actually suffering from neurodegenerative phenotypes of NIID.

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.

Clinical characteristics of two patients with neuronal intranuclear inclusion disease and literature review

Background

Neuronal intranuclear inclusion disease (NIID) is a rare chronic progressive neurodegenerative disease, with complex and diverse clinical manifestations and pathological eosinophilic hyaline intranuclear inclusions in the central and peripheral nervous systems and visceral organs. Improvements in diagnostic methods such as skin biopsy and gene testing are helpful in revealing the clinical and genetic characters of NIID.

Materials and methods

We presented two cases of NIID diagnosed by using NOTCH2NLC gene testing and skin biopsy. Diffusion weighted imaging (DWI) showed high linear intensity in corticomedullary junction. We also reviewed all the published NIID cases with positive NOTCH2NLC GGC repeat expansion and skin biopsy results in PubMed.

Results

Patient 1 was a 63-year-old male who carried 148 GGC repeats and presented with progressive tremor and limb weakness. Patient 2 was a 62-year-old woman who carried 131 GGC repeats and presented with tremors, memory loss and headaches. The most common clinical manifestation of 63 NIID patients in this study was cognitive impairment, followed by tremors. In our study, almost all the patients were from East Asia, the male to female ratio was 1:1.26, with an age of onset of 54.12 ± 14.12 years, and an age of diagnosis of 60.03 ± 12.21 years. Symmetrical high signal intensity at the corticomedullary junction on DWI were revealed in 80.96% of the patients. For the GGC repeat numbers, the majority of GGC repeats were in the 80-119 intervals, with few GGC repeats above 160. The number of GGC repetitions was significantly higher in patients presented with muscle weakness than in other clinical manifestations.

Conclusion

NIID is a neurodegenerative disease caused by aberrant polyglycine (polyG) protein aggregation. NIID mostly occurs in the elderly population in East Asia, with cognitive dysfunction as the most common symptom. Staging NIID based on clinical presentation is inappropriate because most patients with NIID have overlapping symptoms. In our study, there was no significant correlation between the number of GGC repeats and different phenotypes except for muscle weakness. Abnormal trinucleotides repeat and PolyG protein aggregation maybe common pathogenic mechanism in neurodegenerative diseases and cerebrovascular diseases, which needs to be confirmed by more studies.

Clinical features of NOTCH2NLC-related neuronal intranuclear inclusion disease

BACKGROUND

Abnormal expanded GGC repeats within the NOTCH2HLC gene has been confirmed as the genetic mechanism for most Asian patients with neuronal intranuclear inclusion disease (NIID). This cross-sectional observational study aimed to characterise the clinical features of NOTCH2NLC-related NIID in China.

METHODS

Patients with NOTCH2NLC-related NIID underwent an evaluation of clinical symptoms, a neuropsychological assessment, electrophysiological examination, MRI and skin biopsy.

RESULTS

In the 247 patients with NOTCH2NLC-related NIID, 149 cases were sporadic, while 98 had a positive family history. The most common manifestations were paroxysmal symptoms (66.8%), autonomic dysfunction (64.0%), movement disorders (50.2%), cognitive impairment (49.4%) and muscle weakness (30.8%). Based on the initial presentation and main symptomology, NIID was divided into four subgroups: dementia dominant (n=94), movement disorder dominant (n=63), paroxysmal symptom dominant (n=61) and muscle weakness dominant (n=29). Clinical (42.7%) and subclinical (49.1%) peripheral neuropathies were common in all types. Typical diffusion-weighted imaging subcortical lace signs were more frequent in patients with dementia (93.9%) and paroxysmal symptoms types (94.9%) than in those with muscle weakness (50.0%) and movement disorders types (86.4%). GGC repeat sizes were negatively correlated with age of onset (r=-0.196, p<0.05), and in the muscle weakness-dominant type (median 155.00), the number of repeats was much higher than in the other three groups (p<0.05). In NIID pedigrees, significant genetic anticipation was observed (p<0.05) without repeat instability (p=0.454) during transmission.

CONCLUSIONS

NIID is not rare; however, it is usually misdiagnosed as other diseases. Our results help to extend the known clinical spectrum of NOTCH2NLC-related NIID.

Expression of expanded GGC repeats within NOTCH2NLC causes behavioral deficits and neurodegeneration in a mouse model of neuronal intranuclear inclusion disease

GGC repeat expansions within NOTCH2NLC have been identified as the genetic cause of neuronal intranuclear inclusion disease (NIID). To understand the molecular pathogenesis of NIID, here, we established both a transgenic mouse model and a human neural progenitor cells (hNPCs) model. Expression of the NOTCH2NLC with expanded GGC repeats produced widespread intranuclear and perinuclear polyglycine (polyG), polyalanine (polyA), and polyarginine (polyR) inclusions, leading to behavioral deficits and severe neurodegeneration, which faithfully mimicked the clinical and pathological features associated with NIID. Furthermore, conserved alternative splicing events were identified between the NIID mouse and hNPC models, among which was the enrichment of the binding motifs of hnRNPM, an RNA binding protein known as alternative splicing regulator. Expanded NOTCH2NLC-polyG and NOTCH2NLC-polyA could interact with and sequester hnRNPM, while overexpression of hnRNPM could ameliorate the cellular toxicity. These results together suggested that dysfunction of hnRNPM could play an important role in the molecular pathogenesis of NIID.

Case report: Adult-onset neuronal intranuclear inclusion disease with an amyotrophic lateral sclerosis phenotype

Amyotrophic lateral sclerosis (ALS) is one of the differential diagnoses of diseases that occur in adulthood and lead to progressive generalized muscle weakness. Neuronal intranuclear inclusion disease (NIID) is a disease in which histopathologically eosinophilic nuclear inclusion bodies are found in various systems. Both familial and sporadic forms of the disease have been reported. Most cases of sporadic NIID are of the dementia type, in which the main symptom is dementia at the first onset. Familial NIID is more diverse, with the main dominant symptoms being muscle weakness (NIID-M), dementia (NIID-D), and parkinsonism (NIID-P). Furthermore, recently, a GGC-repeat expansion in the Notch 2 N-terminal like C (NOTCH2NLC) gene, which produces a toxic polyglycine-containing protein (uN2CpolyG) in patients with NIID, has been associated with the pathogenesis of ALS. These results suggest that sporadic NIIDs may have more diverse forms. To date, no autopsy cases of NIID patients with an ALS phenotype have been reported. Here, we describe the first autopsy case report of a patient with sporadic NIID who had been clinically diagnosed with ALS. A 65-year-old Japanese man with no family history of neuromuscular disease developed progressive muscle atrophy and weakness in all limbs. The patient was diagnosed with ALS (El Escoriral diagnostic criteria: probable ALS, laboratory-supported ALS). He had no cognitive dysfunction or neuropathies suggestive of NIID. He required respiratory assistance 48 months after onset. He died of pneumonia at the age of 79 years. Postmortem examinations revealed neuronal loss in the spinal anterior horns and motor cortex. In these affected regions, eosinophilic, round neuronal intranuclear inclusions were evident, which were immunopositive for ubiquitin, p62, and uN2CpolyG. No Bunina bodies or TDP-43-positive inclusions were observed in the brain or spinal cord. Our findings suggest that a small proportion of patients with NIID can manifest a clinical phenotype of ALS. Although skin biopsy is commonly used for the clinical diagnosis of NIID, it may also be useful to identify cases of NIID masquerading as ALS.

[Neuronal intranuclear inclusion disease in a patient who exhibited abnormal behavior]

A 63-year-old woman with no medical history of note developed acute-onset abnormal behavior persisting for one week. Mild disturbance of consciousness was noted on physical examination. Her blood and spinal fluid test results were normal. On brain MRI, diffusion-weighted image showed a high-intensity signal in U-fiber areas of the bilateral frontal lobes, and fluid-attenuated inversion recovery showed white matter lesions. We suspected neuronal intranuclear inclusion disease (NIID) based on brain MRI findings; therefore, we performed a skin biopsy and genetic test. Pathological findings of the skin biopsy revealed the presence of anti-p62-positive intranuclear inclusion bodies in fibroblasts and adipocytes. The genetic test showed GGC repeat expansion of NOTCH2NLC, but no mutation of FMR1. Thus, we diagnosed her with NIID. The acute-onset abnormal behavior was improved by levetiracetam. The present case indicates that patients with a high-intensity area in the corticomedullary junction should undergo a skin biopsy, even though they may present with non-specific symptoms such as acute-onset abnormal behavior.

Neuronal intranuclear inclusion disease in patients with adult-onset non-vascular leukoencephalopathy

Neuronal intranuclear inclusion disease (NIID), caused by an expansion of GGC repeats in the 5'-untranslated region of NOTCH2NLC, is an important but underdiagnosed cause of adult-onset leukoencephalopathies. The present study aimed to investigate the prevalence, clinical spectrum, and brain MRI characteristics of NIID in adult-onset nonvascular leukoencephalopathies and assess the diagnostic performance of neuroimaging features. One hundred and sixty-one unrelated Taiwanese patients with genetically undetermined nonvascular leukoencephalopathies were screened for the NOTCH2NLC GGC repeat expansions using fragment analysis, repeat-primed PCR, southern blot analysis and/or nanopore sequencing with Cas9-mediated enrichment. Among them, 32 (19.9%) patients had an expanded NOTCH2NLC allele and diagnosed with NIID. We enrolled another two affected family members from one patient for further analysis. The size of the expanded NOTCH2NLC GGC repeats in the 34 patients ranged from 73 to 323 repeats. Skin biopsy from five patients all showed eosinophilic, p62-positive intranuclear inclusions in the sweat gland cells and dermal adipocytes. Among the 34 NIID patents presenting with nonvascular leukoencephalopathies, the median age at symptom onset was 61 years (range, 41-78 years) and the initial presentations included cognitive decline (44.1%; 15/34), acute encephalitis-like episodes (32.4%; 11/34), limb weakness (11.8%, 4/34), and parkinsonism (11.8%; 4/34). Cognitive decline (64.7%; 22/34) and acute encephalitis-like episodes (55.9%; 19/34) were also the most common overall manifestations. Two-thirds of the patients had either bladder dysfunction or visual disturbance. Comparing the brain MRI features between the NIID patients and individuals with other undetermined leukoencephalopathies, corticomedullary junction curvilinear lesion on diffusion weighted imaging (DWI) was the best biomarker to diagnose NIID with high specificity (98.4%) and sensitivity (88.2%). However, such DWI abnormality was absent in 11.8% of the NIID patients. When only fluid-attenuated inversion recovery images were available, presence of white matter hyperintensity lesions (WMH) either in paravermis or middle cerebellar peduncles also favored the diagnosis of NIID with a specificity of 85.3% and a sensitivity of 76.5%. Among the ten patients' MRI performed within 5 days of the onset of acute encephalitis-like episodes, five showed cortical DWI hyperintense lesions and two revealed focal brain edema. In conclusion, NIID accounts for 19.9% (32/161) of patients with adult-onset genetically undiagnosed nonvascular leukoencephalopathies in Taiwan. Half of the NIID patients ever developed encephalitis-like episodes with restricted diffusion in the cortical regions at the acute stage DWI. Corticomedullary junction hyperintense lesions, WMH in paravermis or middle cerebellar peduncles, bladder dysfunction and visual disturbance are useful hints to diagnose NIID.

Neurodegenerative diseases associated with non-coding CGG tandem repeat expansions

Non-coding CGG repeat expansions cause multiple neurodegenerative disorders, including fragile X-associated tremor/ataxia syndrome, neuronal intranuclear inclusion disease, oculopharyngeal myopathy with leukodystrophy, and oculopharyngodistal myopathy. The underlying genetic causes of several of these diseases have been identified only in the past 2-3 years. These expansion disorders have substantial overlapping clinical, neuroimaging and histopathological features. The shared features suggest common mechanisms that could have implications for the development of therapies for this group of diseases - similar therapeutic strategies or drugs may be effective for various neurodegenerative disorders induced by non-coding CGG expansions. In this Review, we provide an overview of clinical and pathological features of these CGG repeat expansion diseases and consider the likely pathological mechanisms, including RNA toxicity, CGG repeat-associated non-AUG-initiated translation, protein aggregation and mitochondrial impairment. We then discuss future research needed to improve the identification and diagnosis of CGG repeat expansion diseases, to improve modelling of these diseases and to understand their pathogenesis. We also consider possible therapeutic strategies. Finally, we propose that CGG repeat expansion diseases may represent manifestations of a single underlying neuromyodegenerative syndrome in which different organs are affected to different extents depending on the gene location of the repeat expansion.

GGC Repeat Expansion of NOTCH2NLC in Taiwanese Patients With Inherited Neuropathies

BACKGROUND AND OBJECTIVE

The GGC repeat expansion in the 5' untranslated region of NOTCH2NLC was recently identified as the cause of neuronal intranuclear inclusion disease (NIID), which may manifest with peripheral neuropathy. The aim of this study is to investigate its contribution to inherited neuropathy.

METHODS

This cohort study screened patients with molecularly undiagnosed Charcot-Marie-Tooth disease (CMT) and healthy control individuals for the GGC repeat expansion in NOTCH2NLC using repeat-primed PCR and fragment analysis. The clinical and electrophysiological features of the patients harboring the GGC repeat expansion were scrutinized. Skin biopsy with immunohistochemistry staining and electric microscopic imaging were performed.

RESULTS

One hundred and twenty-seven unrelated patients with CMT, including 66 cases with axonal CMT (CMT2), and 200 healthy control individuals were included.Among them, seven CMT patients carried a mutant NOTCH2NLC allele with GGC repeat expansion, but it was absent in controls. The sizes of the expanded GGC repeats ranged from 80 to 104 repeats. All seven patients developed sensory predominant neuropathy with an average age at disease onset of 37.1 years (range 21-55). The electrophysiological studies revealed mild axonal sensorimotor polyneuropathy. Leukoencephalopathy was absent in the five patients who received a brain MRI. Skin biopsy from two patients showed eosinophilic, ubiquitin- and p62-positive intranuclear inclusions in the sweat gland cells and dermal fibroblasts. Two of the seven patients had a family history of NIID.

DISCUSSION

The NOTCH2NLC GGC repeat expansions are an underdiagnosed and important cause of inherited neuropathy. The expansion accounts for 10.6% (7/66) of molecularly unassigned CMT2 cases in the Taiwanese CMT cohort.

CLASSIFICATION OF EVIDENCE

This study provides Class III evidence that in Taiwanese patients with genetically undiagnosed CMT, 10.6% of the CMT2 cases have the GGC repeat expansion in NOTCH2NLC.

Coexistence of neuronal intranuclear inclusion disease and amyotrophic lateral sclerosis: an autopsy case

Background

Neuronal intranuclear inclusion disease (NIID) is a rare neurodegenerative disease. Pathologically, it is characterized by eosinophilic hyaline intranuclear inclusions in the cells of the visceral organs as well as central, peripheral, and autonomic nervous system cells. Recently, a GGC repeat expansion in the NOTCH2NLC gene has been identified as the etiopathological agent of NIID. Interestingly, this GGC repeat expansion was also reported in some patients with a clinical diagnosis of amyotrophic lateral sclerosis (ALS). However, there are no autopsy-confirmed cases of concurrent NIID and ALS.

Case presentation

A 60-year-old Taiwanese woman reported a four-month history of progressive weakness beginning in the right foot that spread to all four extremities. She was diagnosed with ALS because she met the revised El Escorial diagnostic criteria for definite ALS with upper and lower motor neuron involvement in the cervical, thoracic, and lumbosacral regions. She died of respiratory failure at 22 months from ALS onset, at the age of 62 years. Brain magnetic resonance imaging (MRI) revealed lesions in the medial part of the cerebellar hemisphere, right beside the vermis (paravermal lesions). The subclinical neuropathy, indicated by a nerve conduction study (NCS), prompted a potential diagnosis of NIID. Antemortem skin biopsy and autopsy confirmed the coexistence of pathology consistent with both ALS and NIID. We observed neither eccentric distribution of p62-positive intranuclear inclusions in the areas with abundant large motor neurons nor cytopathological coexistence of ALS and NIID pathology in motor neurons. This finding suggested that ALS and NIID developed independently in this patient.

Conclusions

We describe a case of concurrent NIID and ALS discovered during an autopsy. Abnormal brain MRI findings, including paravermal lesions, could indicate the coexistence of NIID even in patients with ALS showing characteristic clinical phenotypes.

GGC Repeat Expansion in the NOTCH2NLC Gene Is Associated With a Phenotype of Predominant Motor-Sensory and Autonomic Neuropathy

There is still a considerable proportion of patients with inherited peripheral neuropathy (IPN) whose pathogenic genes are unknown. This study was intended to investigate whether the GGC repeat expansion in the NOTCH2NLC is presented in some patients with IPN. A total of 142 unrelated mainland Chinese patients with highly suspected diagnosis of IPN without any known causative gene were recruited. Repeat-primed polymerase chain reaction (RP-PCR) was performed to screen GGC repeat expansion in NOTCH2NLC, followed by fluorescence amplicon length analysis-PCR (AL-PCR) to determine the GGC repeat size. Detailed clinical data as well as nerve, muscle, and skin biopsy were reviewed and analyzed in the NOTCH2NLC-related IPN patients. In total, five of the 142 patients (3.52%) were found to have pathogenic GGC expansion in NOTCH2NLC, with repeat size ranging from 126 to 206 repeats. All the NOTCH2NLC-related IPN patients presented with adult-onset motor-sensory and autonomic neuropathy that predominantly affected the motor component of peripheral nerves. While tremor and irritating dry cough were noted in four-fifths of the patients, no other signs of the central nervous system were presented. Electrophysiological studies revealed both demyelinating and axonal changes of polyneuropathy that were more severe in lower limbs and asymmetrically in upper limbs. Sural nerve pathology was characterized by multiple fibers with thin myelination, indicating a predominant demyelinating process. Muscle pathology was consistent with neuropathic changes. P62-positive intranuclear inclusions were observed in nerve, skin, and muscle tissues. Our study has demonstrated that GGC expansion in NOTCH2NLC is associated with IPN presenting as predominant motor-sensory and autonomic neuropathy, which expands the phenotype of the NOTCH2NLC-related repeat expansion spectrum. Screening of GGC repeat expansions in the NOTCH2NLC should be considered in patients presenting with peripheral neuropathy with tremor and irritating dry cough.

GGC repeat expansions in NOTCH2NLC causing a phenotype of distal motor neuropathy and myopathy

Background

The expansion of GGC repeat in the 5' untranslated region of the NOTCH2NLC has been associated with various neurogenerative disorders of the central nervous system and, more recently, oculopharyngodistal myopathy. This study aimed to report patients with distal weakness with both neuropathic and myopathic features on electrophysiology and pathology who present GGC repeat expansions in the NOTCH2NLC.

Methods

Whole‐exome sequencing (WES) and long‐read sequencing were implemented to identify the candidate genes. In addition, the available clinical data and the pathological changes associated with peripheral nerve and muscle biopsies were reviewed and studied.

Results

We identified and validated GGC repeat expansions of NOTCH2NLC in three unrelated patients who presented with progressive weakness predominantly affecting distal lower limb muscles, following negative results in an initial WES. We found intranuclear inclusions with multiple proteins deposits in the nuclei of both myofibers and Schwann cells. The clinical features of these patients are compatible with the diagnosis of distal motor neuropathy and rimmed vacuolar myopathy.

Interpretation

These phenotypes enrich the class of features associated with NOTCH2NLC‐related repeat expansion disorders (NRED), and provide further evidence that the neurological symptoms of NRED include not only brain, spinal cord, and peripheral nerves damage, but also myopathy, and that overlapping symptoms might exist.

Translation of GGC repeat expansions into a toxic polyglycine protein in NIID defines a novel class of human genetic disorders: The polyG diseases

Neuronal intranuclear inclusion disease (NIID) is a neurodegenerative disease characterized by the presence of intranuclear inclusions of unknown origin. NIID is caused by an expansion of GGC repeats in the 5′ UTR of the NOTCH2NLC (N2C) gene. We found that these repeats are embedded in a small upstream open reading frame (uORF) (uN2C), resulting in their translation into a polyglycine-containing protein, uN2CpolyG. This protein accumulates in intranuclear inclusions in cell and mouse models and in tissue samples of individuals with NIID. Furthermore, expression of uN2CpolyG in mice leads to locomotor alterations, neuronal cell loss, and premature death of the animals. These results suggest that translation of expanded GGC repeats into a novel and pathogenic polyglycine-containing protein underlies the presence of intranuclear inclusions and neurodegeneration in NIID.

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NIID is a neurodegenerative disease caused by expansion of GGC repeats in NOTCH2NLC

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These GGC repeats are translated into a polyglycine (polyG) protein

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The polyG protein is toxic and forms intranuclear inclusions in cells and animals

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Similarities between FXTAS and NIID define a new set of disorders: polyG diseases

Neuronal intranuclear inclusion disease: recognition and update

Neuronal intranuclear inclusion disease (NIID) used to be considered as a neurodegenerative disease. Due to the availability of skin biopsy, the diagnostic efficiency of the disease has been greatly improved. Recently, researchers have successfully identified that the GGC repeat expansion in the 5'-untranslated region of the NOTCH2NLC gene is the causative mutation of NIID. Besides the typical phenotype of brain degeneration, peripheral neuropathy, and autonomic disturbance, the gene mutation is also associated with Alzheimer's disease, frontotemporal dementia, Parkinson's disease, multiple system atrophy, essential tremor, adult leukoencephalopathy, and oculopharyngodistal myopathy. However, it still needs more studies to elucidate whether those variable NIID phenotypes can categorize into NOTCH2NLC repeat expansion related disorders. We update the discovery milestone, clinical phenotype, laboratory examinations, as well as new insight into the diagnosis and treatment of NIID. NIID is an unusual degenerative disease that can involve multiple systems, especially involves the nervous system. Originally, it is named after the pathological characteristics with extensive intranuclear eosinophilic inclusions in central and peripheral nervous tissues, as well as in multiple other organs (Sone et al., Brain 139:3170-3186, 2016). In 2019, several research teams from China and Japan have simultaneously identified that the GGC repeat expansion in the 5'-untranslated region (5'UTR) of the NOTCH2NLC gene is the pathogenic mutation of NIID (Ishiura et al., Nat Genet 51:1222-1232, 2019; Deng et al., J Med Genet 56:758-764, 2019; Sone et al., Nat Genet 51:1215-1221, 2019; Sun et al., Brain 143:222-233, 2020; Tian et al., Am J Hum Genet 105:166-176, 2019). Since then, the number of reported NIID cases is rapidly increasing, and the spectrum of NOTCH2NLC repeat expansion related disorders is significantly broadening (Westenberger and Klein, Brain 143:5-8, 2020). However, the NIID associated with GGC repeat expansion of the NOTCH2NLC gene might be account for a part of patients, probably more frequently in the Asian population, because this expansion has not been identified in an European series with postmortem confirmed NIID cases (Chen et al., Ann Clin Transl Neurol 2020). In order to better understand of the disease, we need to revisit the current state of NIID in combination with the findings based on our experiences in recent years and update the concepts about the clinical and pathogenic progression of NIID.

Cognitive profiles in adult-onset neuronal intranuclear inclusion disease: a case series from the memory clinic

OBJECTIVE

This study aimed to analyze the characteristics of cognitive impairment in adult-onset neuronal intranuclear inclusion disease (NIID).

METHODS

Seven patients with adult-onset NIID were collected consecutively from the memory clinic of Xuanwu hospital from February to December 2019. These cases were diagnosed with skin biopsy triggered by DWI high-intensity signals in corticomedullary junction on brain MRI. We used a battery of neuropsychological scales to detect the patient's performance in each cognitive domain, and made a detailed analysis on the characteristics of cognitive impairment.

RESULTS

All seven cases had cognitive impairment, and four of them had met the criteria for dementia. The scores of Montreal Cognitive Assessment and Frontal Assessment Battery were abnormal in all patients. The executive dysfunction was confirmed by the abnormal scores of Trail Making Test (5/7, 71%) and Clock Drawing Test (4/7, 57%). Bad performance in Auditory Verbal Learning Test (6/7, 86%) demonstrated that the memory was also a very commonly impaired cognitive domain. The low score on the animal fluency (4/7, 57%), Boston Naming Test (3/7, 43%), and Pentagon and Cube Copying Test (4/7, 57%) indicated that the language and visuospatial skills were also impaired. Fazekas scores were significantly correlated to the global cognition, executive and language functions (r = 0.788-0.906, P < 0.05).

CONCLUSIONS

There is obvious impairment in multiple cognitive domains in adult-onset NIID, and both the executive dysfunction and memory deficit are very common. Leukoencephalopathy may be the main course of cognitive impairment in adult-onset NIID.

[Neuronal intranuclear inclusion disease (NIID)]

Neuronal intranuclear inclusion disease (NIID) is a progressive neurodegenerative disease that had been diagnosed by autopsy until recently, but the number of cases has increased since skin biopsy was reported to be useful in 2011. In 2019, the genetical cause of NIID was identified as the extension of the GGC repeat sequence on the NOTCH2NLC gene, and genetic diagnosis became possible. In NIID, there are two groups: a group onset with cognitive dysfunction, and with leukoencephalopathy on head MRI and a high intensity signal at the corticomedurally junction on DWI, and a group with limb weakness. It is necessary to include NIID in the differential diagnosis of leukoencephalopathy and neuropathy, and it is necessary to combine skin biopsy and genetic testing to accurately diagnose of NIID and promote pathological elucidation.

A case of neuronal intranuclear inclusion disease with recurrent vomiting and without apparent DWI abnormality for the first seven years

Neuronal intranuclear inclusion disease (NIID) is a rare, neurodegenerative disorder characterized by the presence of eosinophilic hyaline intranuclear inclusions, which are ubiquitin-positive and p62-positive, in neuronal and somatic cells; this can be observed on skin biopsy. Although patients with NIID present with a variety of symptoms that often make the diagnosis difficult, characteristic high-signal intensity of the corticomedullary junction on diffusion-weighted imaging (DWI) often provides a clue to the diagnosis of NIID. We present a case of NIID in a 57-year-old woman who only had recurrent vomiting for four years, which is uncommon as the presenting symptom; moreover, DWI showed no apparent abnormality until a slightly abnormal intensity lesion appeared at the right frontal corticomedullary junction seven years after the first episode of recurrent vomiting. Skin biopsies revealed multiple p62-positive nuclear inclusions, and genetic test showed GGC repeat expansion in NOTCH2NLC; this may form the genetic basis for NIID. Retrospectively, we found that abnormal cerebellar signals besides the vermis in the fluid attenuation inversion recovery (FLAIR) images were detected early-on in the disease. Periodic vomiting may be the only symptom of NIID in the early stages of the disease, and cerebellar abnormalities in FLAIR may serve as an important finding in the diagnosis of NIID, even in the absence of characteristic clinical symptoms or abnormal DWI signals at the cerebral corticomedullary junction.

Neuronal intranuclear inclusion disease presenting with dysphagia: a report of three cases

Neuronal intranuclear inclusion disease (NIID) is a rare neurodegenerative disease that is pathologically characterized by the presence of eosinophilic hyaline intranuclear inclusions in neurons, astrocytes, and specific somatic cells. Previously reported cases of NIID displayed various neurological symptoms, including dementia, muscle weakness, ataxia, etc. However, dysphagia associated with NIID have rarely been reported. Here, we report on three cases of NIID with dysphagia. Bolus mastication and transport were impaired in all three cases. Delay of the initiation of pharyngeal swallowing and silent aspiration was observed in two cases. Combined with the brain magnetic resonance imaging (MRI) findings, oropharyngeal dysphagia associated with NIID was suggested to be attributed to diffuse subcortical lesions.

Phenotypic bases of NOTCH2NLC GGC expansion positive neuronal intranuclear inclusion disease in a Southeast Asian cohort

Neuronal intranuclear inclusion disease (NIID) is a neurodegenerative disorder associated with GGC repeats of >60 to 500 copies in the 5'-untranslated region of NOTCH2NLC. The clinical and genetic characterization of NIID outside of East Asia remains unknown. We identified twelve patients who underwent genetic testing using long-read sequencing or repeat primed polymerase chain reaction. All were positive for a GGC repeat expansion; the median repeat length was 107 (range 92-138). Ten were Chinese and two of Malay ethnicity. Age at onset ranged from 50 to 69 years. Eight (66.7%) patients had dementia, while four (33.3%) patients were oligosymptomatic, without typical NIID symptoms of dementia, Parkinsonism, or muscle weakness. GGA interruptions within the GGC expansion were present in four patients; the number of GGA interruptions was highest (6.71%) in the patient with the earliest age at onset (50 years). Median plasma neurofilament light level was 47.3 pg/mL in seven patients (range 26-380 pg/mL). The highest level (380 pg/mL) was found in one patient who experienced an encephalitic episode. Overall, we describe a cohort of genetically confirmed NIID patients from Southeast Asia and provide further information that the presence of GGA interruptions within GGC repeat expansions may serve as a potential genetic modifier in NIID.

Clinical and pathological features in adult-onset NIID patients with cortical enhancement

BACKGROUND

Neuronal intranuclear inclusion disease (NIID) is a neurodegenerative disease characterized by eosinophilic hyaline intranuclear inclusions in multiple organs. On conventional MRI, high signals on diffused weight image (DWI) along the corticomedullary junction have demonstrated great diagnostic values for adult-onset NIID. However, changes of contrast MRI in the acute period of the encephalopathy-like episode have rarely been investigated.

METHODS

Patients with enhanced lesions were retrieved in our database including 35 patients with adult-onset NIID between October 2017 and December 2019. Conventional and contrast MRI were conducted in all patients. Standard procedures of skin biopsy were performed in all patients. Repeat-primed PCR and amplicon length PCR were used to screen the GGC expansion in the 5'UTR of the NOTCH2NLC gene.

RESULTS

Four of 35 patients (11.4%) were identified to have a cortical enhancement in this study. The enhanced lesions were selectively spread along the surface of posterior cortex and were clinically associated with encephalopathy-like episodes. These patients had a younger age of onset, shorter duration of disease, and a higher incidence of a headache than those without enhancement. Typical p62-postive intranuclear inclusions were observed in all patients, while patient 1 simultaneously had many nuclei full of abnormal substance immunopositive to p62, as well as short-curly filament materials on electron microscopy. All patients were identified to have GGC repeat expansion in the NOTCH2NLC gene.

CONCLUSION

Post-contrast MRI should be routinely performed in the adult-onset NIID patients. Some patients with adult-onset NIID showed cortical enhancement and edema along the surface of posterior cortex, indicating that dehydrate and anti-inflammatory drugs might be potential therapies for these patients.

Identification of expanded repeats in NOTCH2NLC in neurodegenerative dementias

repeat expansion in the NOTCH2NLC gene has been identified to be associated with neuronal intranuclear inclusion disease (NIID). Given the clinical overlap of dementia-dominant NIID with neurodegenerative dementia, we therefore hypothesized that the NOTCH2NLC repeat expansion might also contribute to these diseases. In the present study, repeat primed polymerase chain reaction (RP-PCR) and GC-rich PCR were conducted to detect the repeats of NOTCH2NLC in a cohort of 1004 patients with neurodegenerative dementias from mainland China. As a result, 4 sporadic patients were found to carry the NOTCH2NLC repeats expansion, totally accounting for 0.4% of all dementia individuals, and the accurate repeated sizes were 110, 133,120 and 76 respectively. Of 4 mutation carriers, three and one were clinically diagnosed Alzheimer's disease (AD) and frontotemporal dementia (FTD) respectively. In addition, 3 out of them revealed leukoencephalopathy in T2-Flair imaging. This study revealed that although rare, the NOTCH2NLC repeat expansions may be associated with AD or FTD-like phenotype as well as leukoencephalopathy.

Neuronal Intranuclear Inclusion Disease: Longitudinal Case Report of Motor and Nonmotor Symptoms

Neuronal intranuclear inclusion disease is a rare, neurodegenerative disorder with onset in childhood. We report a single case natural history over 10 years and present a review of juvenile parkinsonism and neuronal intranuclear inclusion disease. Our patient was initially seen at the University of Rochester at age 12 years after 4 years of progressive dysarthria, dysphagia, and clumsiness. His neurologic examination was notable for parkinsonism. He had excellent initial response to levodopa, but subsequently developed dopa-induced motor fluctuations, dyskinesias, psychosis, and dystonia. Later in the course, he developed multiple nonmotor symptoms and ultimately died from respiratory failure. Neuropathology demonstrated large eosinophilic nuclear inclusions and small ubiquitin-related modifier 1 (SUMO-1) immunoreactivity, confirming the diagnosis of neuronal intranuclear inclusion disease. This diagnosis should be considered in a patient presenting with juvenile parkinsonism. Clues to the diagnosis include early-onset dopa-induced dyskinesias, gastrointestinal dysfunction, and oculogyric crises.

Long-read sequencing identifies GGC repeat expansions in NOTCH2NLC associated with neuronal intranuclear inclusion disease

. The average onset age is 59.7 years among approximately 140 NIID cases consisting of mostly sporadic and several familial cases. By linkage mapping of a large NIID family with several affected members (Family 1), we identified a 58.1 Mb linked region at 1p22.1-q21.3 with a maximum logarithm of the odds score of 4.21. By long-read sequencing, we identified a GGC repeat expansion in the 5' region of NOTCH2NLC (Notch 2 N-terminal like C) in all affected family members. Furthermore, we found similar expansions in 8 unrelated families with NIID and 40 sporadic NIID cases. We observed abnormal anti-sense transcripts in fibroblasts specifically from patients but not unaffected individuals. This work shows that repeat expansion in human-specific NOTCH2NLC, a gene that evolved by segmental duplication, causes a human disease.

Expansion of Human-Specific GGC Repeat in Neuronal Intranuclear Inclusion Disease-Related Disorders

Neuronal intranuclear inclusion disease (NIID) is a slowly progressing neurodegenerative disease characterized by eosinophilic intranuclear inclusions in the nervous system and multiple visceral organs. The clinical manifestation of NIID varies widely, and both familial and sporadic cases have been reported. Here we have performed genetic linkage analysis and mapped the disease locus to 1p13.3-q23.1; however, whole-exome sequencing revealed no potential disease-causing mutations. We then performed long-read genome sequencing and identified a large GGC repeat expansion within human-specific NOTCH2NLC. Expanded GGC repeats as the cause of NIID was further confirmed in an additional three NIID-affected families as well as five sporadic NIID-affected case subjects. Moreover, given the clinical heterogeneity of NIID, we examined the size of the GGC repeat among 456 families with a variety of neurological conditions with the known pathogenic genes excluded. Surprisingly, GGC repeat expansion was observed in two Alzheimer disease (AD)-affected families and three parkinsonism-affected families, implicating that the GGC repeat expansions in NOTCH2NLC could also contribute to the pathogenesis of both AD and PD. Therefore, we suggest defining a term NIID-related disorders (NIIDRD), which will include NIID and other related neurodegenerative diseases caused by the expanded GGC repeat within human-specific NOTCH2NLC.

Two cases of sporadic adult-onset neuronal intranuclear inclusion disease preceded by urinary disturbance for many years

Neuronal intranuclear inclusion disease (NIID) is a neurodegenerative disease defined by the presence of eosinophilic hyaline intranuclear inclusions. The initial and main clinical feature of adult-onset NIID is predominantly dementia. We present herein 2 cases of sporadic adult-onset NIID with longstanding urinary disturbance prior to development of other neurological symptoms. Case 1: A 71-year-old woman was admitted after she lost consciousness while bathing. She presented slowly progressive bladder dysfunction starting at the age of 40. Recently, she complained of recurrent light-headedness on standing. Her neurological findings showed miosis, muscle weakness, rigidity, hyporeflexia, sensory disturbance, cerebellar ataxia, and orthostatic hypotension. Case 2: A 68-year-old man was admitted because of episodes of transient loss of consciousness. Ten years earlier, he had developed urinary dysfunction. His neurological findings revealed cognitive dysfunction, cerebellar ataxia, and hyporeflexia. Both patients had leukoencephalopathy and motor-sensory neuropathy. In both cases, diffusion-weighted imaging showed high-intensity signals in the corticomedurally junction; and skin biopsy samples revealed ubiquitin-positive intranuclear inclusions. Therefore, we made a diagnosis of adult-onset NIID. Although numerous cases of this disorder have been reported in the past, there were only a few cases showing the development of other neurological symptoms after longstanding urinary disturbance. Our cases suggest that it is worthwhile considering the possibility of NIID in cases with a long-term history of neurogenic bladder dysfunction.

[Sporadic adult-onset neuronal intranuclear inclusion disease with abnormal electroretinogram, nerve conduction studies and somatosensory evoked potential]

A 70-year-old man, a urinary retention of unknown origin from 10 years ago, decreased cognitive function from 4 years ago, vision impairment advanced a year ago. Brain MRI with DWI showed high intensity erea in the cortico-medullary junction. We diagnosed as intranuclear inclusion body disease (NIID) because of p62-positive intranuclear inclusion bodies by skin biopsy. Electroretinogram revealed amplitude reduction in the cone response superiority. Nerve conduction test showed mild conduction velocity reduction. Furthermore, in the somatosensory evoked potential of the lower limb, latency of the first cortical component was prolonged. These electrophysiological abnormalities were considered to be associated with the pathological features of NIID.

Adult-onset neuronal intranuclear hyaline inclusion disease is not rare in older adults

Neuronal intranuclear hyaline inclusion disease (NIHID) is a rare neurodegenerative disorder pathologically characterized by localized neuronal loss, and the presence of eosinophilic intranuclear inclusions in neurons and glial cells. NIHID is a heterogeneous disease entity. It is divided into three clinical subgroups: infantile, juvenile and adult forms. Recently, reports of adult-onset cases have increased. Typical adult-onset NIHID consists of cognitive dysfunction with leukoencephalopathy. This type of adult-onset NIHID can be predicted by characteristic magnetic resonance images, high intensity areas on T2-weighted/fluid-attenuated inversion recovery images and persistent high intensity at the corticomedullary junction in diffusion-weighted images. When clinically suspected, the ante-mortem diagnosis can be made by biopsy. In adult-onset NIHID, nuclear inclusions are found more frequently in glial cells, and moderate to severe white matter degeneration is often associated. Although the underlying pathological mechanisms of NIHID are largely unknown, abnormal intranuclear accumulations of proteins and/or dysfunction of protein degradation systems might be related to the pathogenesis. To further clarify the characteristics of this disease entity, biological and pathological analysis of the patients is indispensable. As this disease entity becomes better known, diagnosed cases are expected to increase. Adult-onset NIHID might not be as extremely rare as previously thought.

Clinicopathological features of adult-onset neuronal intranuclear inclusion disease

Neuronal intranuclear inclusion disease (NIID) is a slowly progressive neurodegenerative disease characterized by eosinophilic hyaline intranuclear inclusions in the central and peripheral nervous system, and also in the visceral organs. NIID has been considered to be a heterogeneous disease because of the highly variable clinical manifestations, and ante-mortem diagnosis has been difficult. However, since we reported the usefulness of skin biopsy for the diagnosis of NIID, the number of NIID diagnoses has increased, in particular adult-onset NIID. In this study, we studied 57 cases of adult-onset NIID and described their clinical and pathological features. We analysed both NIID cases diagnosed by post-mortem dissection and by ante-mortem skin biopsy based on the presence of characteristic eosinophilic, hyaline and ubiquitin-positive intanuclear inclusion: 38 sporadic cases and 19 familial cases, from six families. In the sporadic NIID cases with onset age from 51 to 76, dementia was the most prominent initial symptom (94.7%) as designated 'dementia dominant group', followed by miosis, ataxia and unconsciousness. Muscle weakness and sensory disturbance were also observed. It was observed that, in familial NIID cases with onset age less than 40 years, muscle weakness was seen most frequently (100%), as designated 'limb weakness group', followed by sensory disturbance, miosis, bladder dysfunction, and dementia. In familial cases with more than 40 years of onset age, dementia was most prominent (100%). Elevated cerebrospinal fluid protein and abnormal nerve conduction were frequently observed in both sporadic and familial NIID cases. Head magnetic resonance imaging showed high intensity signal in corticomedullary junction in diffusion-weighted image in both sporadic and familial NIID cases, a strong clue to the diagnosis. All of the dementia dominant cases presented with this type of leukoencephalopathy on head magnetic resonance imaging. Both sporadic and familial NIID cases presented with a decline in Mini-Mental State Examination and Frontal Assessment Battery scores. Based on these clinicopathological features, we proposed a diagnosis flow chart of adult-onset NIID. Our study suggested that the prevalence rate of adult-onset NIID may be higher than previously thought, and that NIID may be underdiagnosed. We should take NIID into account for differential diagnosis of leukoencephalopathy and neuropathy.

Clinical aspects of neurointestinal disease: Pathophysiology, diagnosis, and treatment

The enteric nervous system (ENS) is involved in the regulation of virtually all gut functions. Conditions referred to as enteric neuropathies are the result of various mechanisms including abnormal development, degeneration or loss of enteric neurons that affect the structure and functional integrity of the ENS. In the past decade, clinical and molecular research has led to important conceptual advances in our knowledge of the pathogenetic mechanisms of these disorders. In this review we consider ENS disorders from a clinical perspective and highlight the advancing knowledge regarding their pathophysiology. We also review current therapies for these diseases and present potential novel reparative approaches for their treatment.

Memory Loss and Frontal Cognitive Dysfunction in a Patient with Adult-onset Neuronal Intranuclear Inclusion Disease

Neuronal intranuclear inclusion disease (NIID) is an uncommon progressive neurodegenerative disorder. Adult-onset NIID can result in prominent dementia. We herein describe the case of a 74-year-old man who presented with dementia, cerebellar ataxia, neuropathy, and autonomic dysfunction. Diffusion-weighted imaging showed hyperintensity of the corticomedullary junction. Fluid-attenuated inversion recovery images showed frontal-dominant white matter hyperintensity. NIID was diagnosed from the presence of intranuclear inclusions in a skin biopsy sample. Neuropsychological testing revealed memory loss and frontal cognitive dysfunction, especially in relation to language and executive functions. We were therefore able to confirm the association of NIID with cognitive dysfunction.

Neuronal intranuclear inclusion disease presenting with resting tremor

Neuronal intranuclear inclusion disease (NIID) is a rare neurodegenerative disease with various neurological symptoms. A 73-year-old woman presented with slowly progressive tremor in both hands. The resting tremor was enhanced by cognitive activity and walking. However, there were no other signs of parkinsonism. Levodopa and trihexyphenidyl were ineffective against the tremor. A diagnosis of NIID was made based on skin biopsy findings. The tremor in this case was very similar to that seen in Parkinson's disease (PD). Previous reports and the present case indicate that NIID patients can develop tremor that is similar in character to that seen in PD. NIID should be considered in the differential diagnosis of resting tremor similar to PD.

FUS immunoreactivity of neuronal and glial intranuclear inclusions in intranuclear inclusion body disease

AIMS

Recent studies have shown that fused-in-sarcoma (FUS) protein is a component of 'neuronal' intranuclear inclusion bodies (INIBs) in the brains of patients with intranuclear inclusion body disease (INIBD). However, the extent and frequency of FUS-immunoreactive structures in INIBD are uncertain.

METHODS

We immunohistochemically examined the brain, spinal cord and peripheral ganglia from five patients with INIBD and five control subjects, using anti-FUS antibodies.

RESULTS

In controls, the nuclei of both neurones and glial cells were intensely immunolabelled with anti-FUS and neuronal cytoplasm was weakly positive for FUS. In INIBD, neuronal and glial INIBs in the brain and spinal cord were positive for FUS. FUS-positive INIBs were also found in the peripheral ganglia. The proportion of FUS-positive neuronal INIBs relative to the total number of inclusion-bearing neurones ranged from 55.6% to 83.3% (average 73.2%) and that of FUS-positive glial INIBs ranged from 45.9% to 85.7% (average 62.7%). The nucleus and cytoplasm of inclusion-bearing neurones and glial cells showed no FUS immunoreactivity.

CONCLUSIONS

These findings suggest that FUS is incorporated into INIBs in both neurones and glial cells and that loss of normal FUS immunoreactivity may result from reduced protein expression and/or sequestration within inclusions.

Ubiquitin-related proteins in neuronal and glial intranuclear inclusions in intranuclear inclusion body disease

Recent studies have shown that eosinophilic intranuclear inclusions (INI) in the brain of patients with intranuclear inclusion body disease (INIBD) are immunopositive for ubiquitin and ubiquitin-related proteins (URP). However, the extent and frequency of URP-immunoreactive inclusions in INIBD are uncertain. We immunohistochemically examined the brain, spinal cord and dorsal root ganglia from five patients with INIBD, using a virtual slide system with sequential staining of the same sections with hematoxylin and eosin and by immunolabeling with antibodies against ubiquitin and URP (NEDD8, NUB1, SUMO-1 and SUMO-2). Intranuclear inclusions were widely distributed in neurons and glial cells in all the cases. Sequential staining revealed that 100% of INI in neurons and glial cells were positive for ubiquitin. Moreover, the majority or a significant proportion of INI were positive for NEDD8, NUB1, SUMO-1 and SUMO-2. However, the proportions of NEDD8-, NUB1- and SUMO-1-positive inclusions were significantly higher in neurons than in glial cells (P < 0.05). These findings suggest that proteins related to ubiquitination and proteasomal degradation are involved in the formation of INI in INIBD.

Genetics of human enteric neuropathies

Knowledge of molecular mechanisms that underlie development of the enteric nervous system has greatly expanded in recent decades. Enteric neuropathies related to aberrant genetic development are thus becoming increasingly recognized. There has been no recent review of these often highly morbid disorders. This review highlights advances in knowledge of the molecular pathogenesis of these disorders from a clinical perspective. It includes diseases characterized by an infantile aganglionic Hirschsprung phenotype and those in which structural abnormalities are less pronounced. The implications for diagnosis, screening and possible reparative approaches are presented.