Neuronal intranuclear inclusion disease: neuropathologic study of a case

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.

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.

Clinical and mechanism advances of neuronal intranuclear inclusion disease

Due to the high clinical heterogeneity of neuronal intranuclear inclusion disease (NIID), it is easy to misdiagnose this condition and is considered to be a rare progressive neurodegenerative disease. More evidence demonstrates that NIID involves not only the central nervous system but also multiple systems of the body and shows a variety of symptoms, which makes a clinical diagnosis of NIID more difficult. This review summarizes the clinical symptoms in different systems and demonstrates that NIID is a multiple-system intranuclear inclusion disease. In addition, the core triad symptoms in the central nervous system, such as dementia, parkinsonism, and psychiatric symptoms, are proposed as an important clue for the clinical diagnosis of NIID. Recent studies have demonstrated that expanded GGC repeats in the 5′-untranslated region of the NOTCH2NLC gene are the cause of NIID. The genetic advances and possible underlying mechanisms of NIID (expanded GGC repeat-induced DNA damage, RNA toxicity, and polyglycine-NOTCH2NLC protein toxicity) are briefly summarized in this review. Interestingly, inflammatory cell infiltration and inflammation were observed in the affected tissues of patients with NIID. As a downstream pathological process of NIID, inflammation could be a therapeutic target for NIID.

CGG expansion in NOTCH2NLC is associated with oculopharyngodistal myopathy with neurological manifestations

Oculopharyngodistal myopathy (OPDM) is a rare hereditary muscle disease characterized by progressive distal limb weakness, ptosis, ophthalmoplegia, bulbar muscle weakness and rimmed vacuoles on muscle biopsy. Recently, CGG repeat expansions in the noncoding regions of two genes, LRP12 and GIPC1, have been reported to be causative for OPDM. Furthermore, neuronal intranuclear inclusion disease (NIID) has been recently reported to be caused by CGG repeat expansions in NOTCH2NLC. We aimed to identify and to clinicopathologically characterize patients with OPDM who have CGG repeat expansions in NOTCH2NLC (OPDM_NOTCH2NLC). Note that 211 patients from 201 families, who were clinically or clinicopathologically diagnosed with OPDM or oculopharyngeal muscular dystrophy, were screened for CGG expansions in NOTCH2NLC by repeat primed-PCR. Clinical information and muscle pathology slides of identified patients with OPDM_NOTCH2NLC were re-reviewed. Intra-myonuclear inclusions were evaluated using immunohistochemistry and electron microscopy (EM). Seven Japanese OPDM patients had CGG repeat expansions in NOTCH2NLC. All seven patients clinically demonstrated ptosis, ophthalmoplegia, dysarthria and muscle weakness; they myopathologically had intra-myonuclear inclusions stained with anti-poly-ubiquitinated proteins, anti-SUMO1 and anti-p62 antibodies, which were diagnostic of NIID (typically on skin biopsy), in addition to rimmed vacuoles. The sample for EM was available only from one patient, which demonstrated intranuclear inclusions of 12.6 ± 1.6 nm in diameter. We identified seven patients with OPDM_NOTCH2NLC. Our patients had various additional central and/or peripheral nervous system involvement, although all were clinicopathologically compatible; thus, they were diagnosed as having OPDM and expanding a phenotype of the neuromyodegenerative disease caused by CGG repeat expansions in NOTCH2NLC.

Interrelated Pathogenesis? Neuronal Intranuclear Inclusion Disease Combining With Hemiplegic Migraine

BACKGROUND

Neuronal intranuclear inclusion disease (NIID) is considered a heterogeneous disease because of its highly variable clinical manifestations. To date, there are no reports of NIID patients presenting with hemiplegic migraine (HM)-like headache, or of HM and NIID co-occurring as comorbidity, and the connection between these 2 seemingly unrelated clinical conditions has yet to be established.

METHOD

We present a patient with NIID who was previously diagnosed with HM. To determine the pathogenesis of HM in this NIID patient, we systematically reviewed published NIID and HM cases and cataloged them based on their clinical manifestations.

RESULT

The clinical manifestations of NIID is highly various; however, there is no case reported to date that shows HM-like symptoms or cerebral edema. All documented symptomatic HM cases show vascular dysfunction to various degrees, but none of them has been shown to be correlated with NIID.

CONCLUSION

Our patient is the first documented case in which HM and NIID occur simultaneously. Vascular dysfunctions that cause cerebral hypoperfusion and glucose hypometabolism, two of the dominant causes of symptomatic HM, may be associated with the accumulation of eosinophilic hyaline inclusions that cause NIID. However, the existence of inclusions may also alter neuronal behavior and indirectly cause cerebral hypoperfusion and glucose hypometabolism. Further research and observations are needed to examine the relationship between HM and NIID.

Neuronal intranuclear inclusion disease: two cases of dopa-responsive juvenile parkinsonism with drug-induced dyskinesia

There are very few conditions that present with dopa-responsive juvenile parkinsonism. We present two such children with neuronal intranuclear inclusion disease (NIID) who had an initial good levodopa response that was soon complicated by disabling dopa-induced dyskinesia. One child was diagnosed by rectal biopsy in life, and the other diagnosis was confirmed at postmortem. In this patient, dopamine transporter imaging showed severely decreased binding of the radiotracer in the striatum on both sides. Bilateral subthalamic deep brain stimulation in this patient produced initial improvement, but this was not sustained. Both patients died within 10 years of symptom onset. As well as levodopa responsiveness with rapid onset of dyskinesia, clues to the diagnosis of NIID in patients presenting with parkinsonism include the presence of gaze-evoked nystagmus, early onset dysarthria and dysphagia and oculogyric crises. Differential diagnosis of clinical symptoms and neuropathological findings are discussed including the approach to rectal biopsy for early diagnosis.

Neuronal intranuclear inclusion disease without polyglutamine inclusions in a child

Neuronal intranuclear inclusion disease (NIID) is a rare and heterogeneous group of slowly progressive neurodegenerative disorders characterized by the widespread presence of eosinophilic neuronal intranuclear inclusions (NII) accompanied by a more restricted pattern of neuronal loss. We report here the pathologic findings in a 13-year-old boy who died after a 6-year clinical history of progressive ataxia, extrapyramidal manifestations, and lower motor neuron abnormalities. Histological evaluation of the brain revealed widespread NII in most neurons. Marked loss of cerebellar Purkinje cells and neurons in the dentate nucleus, red nucleus, and spinal cord anterior horns was accompanied by a modest astrocytosis. Because of the abundance of NII and the absence of a relationship between NII and neuronal loss or microglial activation, we conclude that loss of cerebellar, brainstem, and spinal cord neurons reflects selective neuronal vulnerability. NII were immunoreactive for ubiquitin, glucocorticoid receptor, and SUMO-1, a small, ubiquitin-like protein purportedly involved in protein transport and gene transcription. NII were non-reactive for polyglutamine (1C2), TATA binding protein, promyelocytic leukemia protein, heat shock protein 90, tau, alpha-synuclein, neurofilament, and beta amyloid. The moderate ubiquitin and strong SUMO-1 staining of NII in juvenile cases is the reverse of the pattern noted in adult diseases, suggesting the two age groups are pathogenically distinct. We suggest that juvenile NIID is a spinocerebellar brainstem ataxic disease possibly related to an abnormality in SUMOylation.

Neuronal intranuclear hyaline inclusion disease

Neuronal intranuclear hyaline inclusion disease (NIHID) is a rare neurodegenerative disorder characterized pathologically by the presence of eosinophilic intranuclear inclusions in neuronal and glial cells. It has been considered to be a heterogeneous disease entity because the clinical pictures of previously described cases were highly variable. In the present review, reported NIHID cases have been categorized into three clinical subgroups according to onset and disease duration, and the clinical phenotype of each subgroup is discussed. Neuronal intranuclear inclusions (NII) in NIHID are ubiquitinated and their prevalence is inversely correlated with neuronal loss, suggesting that NII formation is a protective mechanism involving the ubiquitin-proteasome-dependent proteolytic pathway. In several polyglutamine diseases, disease-related proteins containing abnormally expanded polyglutamine tracts aggregate in neuronal nuclei, resulting in NII formation. The similarity between NII in NIHID and polyglutamine diseases suggests that they are formed during a common proteolysis-related process that takes place in the nucleus. Although the pathogenetic mechanism underlying NIHID remains unknown, the data reviewed here suggest that it might be related to accumulation of as yet unidentified abnormal proteins or dysfunction of the intranuclear ubiquitin-proteasome pathway.

Recruitment of nonexpanded polyglutamine proteins to intranuclear aggregates in neuronal intranuclear hyaline inclusion disease

Recruitment of polyglutamine-containing proteins into nuclear inclusions (NIs) was investigated in neuronal intranuclear hyaline inclusion disease (NIHID). Some polyglutamine-containing proteins, ataxin-2, ataxin-3, and TATA box binding protein (TBP), as well as unidentified proteins with expanded polyglutamine tracts were recruited into NIs with different frequencies. Ataxin-3 was incorporated into most of the NIs and disappeared from its normal cytoplasmic localization, whereas only a small fraction of NIs contained ataxin-2 and TBP. The consistent presence of ataxin-3 in NIs could reflect a biological feature of wild-type ataxin-3, which is translocated into the nucleus under pathological conditions and participates in the formation of aggregates. Ataxin-2 also accumulated in the nucleus, but was not necessarily incorporated into NIs, suggesting that transport of these cytoplasmic proteins into the nucleus and their recruitment into NIs are not wholly explained by an interaction with a polyglutamine stretch and must be regulated in part by other mechanisms. The prevalence of ubiquitin-immunopositive NIs was inversely correlated to neuronal loss in all cases examined. This correlation could be explained if NI formation is a protective mechanism involving the ubiquitin-proteasome pathway. This hypothesis is supported by the finding that the polyglutamine epitope in the center of NIs was surrounded by ubiquitin.